Toyota Yaris Mark 4: Voltmeter readings for 12V battery

[@SOMEONE-ME]

It's known problem and Toyota is going to fix it now based on new procedure for battery testing. Programme is rolling out now in Poland so I assume it will be in whole EU. Toyota needs to roll out procedure and supply new testers for dealers. Whole issue is down to COVID, lack of batteries and bad choice of Turkish supplier which end up been rubbish. Whole problem was raised by one of the Polish Toyota dealers and then escalated to Toyota headquarters. It took time but they admitted issue and now it will be fixed at no charge in form of battery replacement from different supplier.

[@Helpful-Stuff]

I have just had my 12V battery replaced under warranty because my car failed to start when it was only 10 months with about 6,200miles on the clock after just one day without use. My dealer has been very helpful and told me that the new battery was the "same spec" as the original factory fitted battery. However, I now realise that he did not say the new battery was from the same manufacturer as the factory fitted battery. Do you know the manufacturer of the new 12V batteries that will replace the bad Turkish batteries? I will then lift my rear seat and check if I have got a battery from the new supplier or the old Turkish supplier.

[@SOMEONE-ME]

@@Helpful-Stuff I don’t know. Spec is probably the same. Issue is with actual brand which doesn’t perform properly, so Toyota changed it. It also depends when you had it replaced. Things just started processing, Toyota is introducing new testing procedure using new equipment. Apparently good question to ask is - “has my battery been tested according to new procedure?” Since they replaced it ( before they weren’t doing it) I assume you have new battery which should be fine.

[@Helpful-Stuff]

My battery was changed 4 days ago ... so from what you are saying I think there is a very good chance that I have got a new 12V battery from the good manufacturer. Good news 😀 Thanks for the comment ... it is very useful information. Is it OK to make a video where I use the information that you have shared so that more people get to know about this? I guess from your anonymous KZbin account name you would prefer to not be quoted directly so I will just say something like "I have discovered that ...."

[@SOMEONE-ME]

@@Helpful-Stuff Yes. It’s public info shared by Toyota insider. You just have to speak Polish, but you can use Google translate. I would have to find it though as I stamp on it accidentally.

[@Helpful-Stuff]

I have tried to find it using Google's advanced search to only search websites in Polish ...unfortunately no luck so far. If you do find it again I would very grateful if you can paste the link into this discussion. Thanks again for the information. 👍

[@4586johnc]

Thankyou for the info. I also have a Yaris, with the same battery issues. Unfortunately I do not drive the car on a daily basis and on several occasions have had a flat battery and been unable to start the car. I bought a small AA Solar panel which I set up in the windscreen area when the car is parked. This produces about 19 Volts at a very small current, and is usually sufficient to overcome my no starting problem. The battery which is fitted to my Yaris is actually insufficient to provide a necessary charge to sustain the electronic drain on its complex circuitry, in a situation where the car isn’t driven for a few days. This should have been addressed by the Toyota design team. Imagine leaving the car at an airport carpark for a 2 weeks holiday. On return you would have a completely flat battery. Given the type of driving I do, I would not buy another Yaris.

[@Helpful-Stuff]

My dealer has been extremely helpful during my "12V battery problem". They recommended the AA solar panel and they even fitted the cable free of charge so that it is a LOT easier to plug and unplug the solar panel kzbin.info/www/bejne/pWmwnHmLhcuXrLM .... before the cable was fitted I had to get down on my knees to plug the solar panel's cable into the OBD socket below the steering wheel!!! It only took my dealer 10minutes to install the cable - they told me that only 2 screws need to be undone. If you are good at DIY then you may be able to do this yourself ... or if not then it may be worth asking your dealer ... from what I read some dealers are helpful and others are not so helpful. I am lucky I have got a very helpful dealer. I owned a Yaris Mark 3 Hybrid for 5 years and had no starting problems even during COVID lockdowns when I only used the car once per week. My Yaris Mark 4 failed to start after a single day parked kzbin.info/www/bejne/Y4bOo4itpdCYhq8 The small 12V battery problem is an issue for all manufacturers so I have looked at how other car manufacturers are handling the problem ... Kia and Hyundai Hybrids have a 12V Reset which prevents the 12V battery from being drained. MG EVs show the 12V battery voltage in the app. Toyota do not have a voltmeter on the dash or in the app and nothing like the 12V Reset button. My own view is that Toyota made a major mistake with the 12V design but they will not admit it because the cost of fixing the problem in every Yaris that has been sold is too high. So instead they are blaming customers for not driving enough!!!! I think this strategy will backfire in a big way on Toyota ... Toyota used to have a reputation for building reliable cars. The design flaw in the Yaris and the corporate arrogance in deciding to blame customers will be Toyota's downfall ... I think they will lose the reliability reputation as a result and will be paying for this for years in terms of lower sales. Like you I would not buy another Toyota ... even though my current car is my 3rd Toyota ... 2005 to 2018 Landcruiser ... 2018-2022 Yaris Mark 3 ... 2022 to date Yaris Mark 4

[@philiphiggins2818]

Very informative video. I have this week fitted a voltmeter as shown and I am getting very similar readings as yourself. Once a week I fit a CTEC battery charger to the jump start terminals to give my battery a boost. It normally only takes one hour to a full charge condition. Since carrying out using this procedure I very often get a 12.7 volt reading for the instantaneous reading prior to engine ready which then goes to 14.7 volts. If we go away in the car for a break I will use the charging function in ready mode. I was going to purchase a jump starter pack but I will hold off for a while. For your information my Yaris is a mark 4, 11 month old and has 1,950 miles on the clock.

[@Helpful-Stuff]

Thanks for your comment and age/mileage information. My car is a couple of months older but has done a lot more miles ... I have just done 10,000miles. Its interesting that you are seeing 12.7V for the instantaneous reading immediately after starting the car. The highest I have seen in my car is 12.2V and that is on the 2nd or 3rd start of the day. It looks like the CTEK charger is a better battery charger than the 12V battery charging system built into the Yaris. Or another possibility is that my 12V battery was damaged by the single failure to start that I have experienced. I think this confirms that the voltmeter was a good purchase and I need to keep an eye on the voltages. I know what the normal voltages for my car are now ... if I start to see the voltages dropping then I think I will have to buy a new 12V battery. I have an allocated off road car parking space but unfortunately there isn't a 240V mains socket anywhere near it so I do not have the option of using a CTEK charger. Hence the reason I do the once a week wash + charge in READY mode.

[@roberttroutman6780]

I have several newer gas powered cars and have been using plug-in voltmeters to check the battery voltage both before and after starting the engine. As in this video, the voltage readings are very similar and the higher voltage readings are indicating the voltage output of the alternator. Very useful in noting the state of charging of the battery, at all times, and the output of the alternator. This is especially useful for cars not equipped with a voltmeter.

[@Helpful-Stuff]

Thanks for watching the video and also the feedback that you are seeing similar voltages 👍

[@raycao6764]

This video is really informative. It shows the main battery will charge 12v battery from beginning of start the car. What I guess, if the main battery doesn't have sufficient voltage, the 12v battery will be used to start the engine immediately to recharge the main battery. In this scenario, if 12v battery is old and not able able drive the starter, then car will failed to start. However, the main battery run of juice should be rare. Not sure if extremely low temperature caused the both battery voltage drop and failed to start the engine.

[@Helpful-Stuff]

Thanks. I am glad you enjoyed the video and found it informative. I have to be honest I do not fully understand exactly how the petrol engine is started but I know it is nothing to do with the 12V battery and there is definitely no starter motor in a Toyota Hybrid. The petrol engine is started by the big traction battery which can somehow start the petrol engine very quickly. I think I have read somewhere that the petrol engine can start is less than one cycle of the engine - this is much faster than with a starter motor. In a normal petrol car the voltage is not that important but the 12V battery must be able to provide lots of current to the starter motor. In a Hybrid there is no starter motor so the 12V battery does not need to provide a lot of current but it must be able to provide a good voltage to the computers. If the voltage is low then the computers will detect this and the computers will not even try to start the Hybrid drive - so neither the petrol or electric motors will start. When my car refused to start the AA man measured the voltage and it was only 9.45V. kzbin.info/www/bejne/Y4bOo4itpdCYhq8 In a petrol car when the battery is almost flat you can hear the starter motor spinning but not fast enough for the petrol engine to start. When a Toyota Hybrid fails to start there is no sound ... just the dashboard display saying "Not ready to drive". I often think that when I turn my Yaris Hybrid on I am not starting a car ... all I am doing is turning the computers on. On a cold day the petrol engine will start almost immediately ... but on a hot day, especially if the car has already been driven that day, the petrol engine may not be switched on until I have pulled out of the car park and need some acceleration. Since making this video I have discovered that Toyota Poland have admitted that there is a problem with the 12V battery in the Yaris. All the Toyota dealers in Poland now have new 12V battery test equipment and procedures and will replace any 12V battery that fails the new tests with a new 12V battery under warranty. I do not know if Toyota GB and all the UK dealers have got this new test equipment and warranty replacement procedures. kzbin.info/www/bejne/e3nXmGtnoLJgfLc The problem seems to be the factory fit Mutlu 12V battery. Toyota have now replaced my 12V battery. I haven't checked but I think it is a new Mutlu battery. The new battery is giving me voltages about 0.5V higher than my old battery which I had when I made this video. The new battery has never shown a reading below 12V. If this new battery does start to show readings below 12V I am going to go to a local garage and ask them to change the 12V battery to a Yuasa battery which I have read are much higher quality than the Toyota specified Mutlu battery. I will not go to a Toyota dealer because I think they will only fit the Mutlu battery since this is what is specified by Toyota. If you read the Owners manual there is nothing that states that you must use a Mutlu battery ... only that you must use a battery that meets specification "LN0, 35Ah and 264A". In order to try and keep my new battery healthy I am putting the car into READY mode for 60 minutes each week ... I wash my car while I do this kzbin.info/www/bejne/eZmQfWOAl8eEi8k I have to say it is a good job that in all other ways I think my Yaris Excel with Tech pack is a fantastic car ... in fact I think that it is the best car I have ever bought. Unfortunately I also think it is the worst car I have ever bought because a car bought from new should not fail to start when only 10 months old and after being parked and not used for just 1 day.

[@garryspencer1193]

Hi. I have a c-hr 2.0. Even though it’s not a Yaris. Thought it was quite interesting to see that it was giving the same sort of reading. Great idea for the tester 👍.

[@Helpful-Stuff]

2 months after I made this video Toyota GB agreed to change my 12V battery. I have now had the new 12V battery for almost 4 months and the voltages that I am seeing on my voltmeter are around 0.5V higher than the voltages shown in the video. I have never seen the new battery show a voltage of less than 12V. The most common reading is 12.3V. This has really surprised me because my old battery regularly showed less than 12V (as shown in the video) so I think this must mean that my old 12V battery was degraded i.e. it was not completely damaged an unusable but it could not be considered 100% healthy. The battery was degraded such that my 10 month old Yaris was unable to hold sufficient charge when the car was parked for just one day to start the car the following day. Since a lot of Yaris Mark 4s fail to start I do not believe that I was unlucky and got a bad battery ... I think Toyota have chosen a very low quality 12V battery to factory fit. Thanks to comments on other videos I have also discovered that Toyota Poland have admitted that there is a problem with the Yaris and all Polish dealers have got new 12V battery test equipment and procedures and any batteries that fail the new tests will be replaced under warranty. kzbin.info/www/bejne/e3nXmGtnoLJgfLc Because my new battery is exactly the same as my old battery I expect that if I do nothing it will fail again in around 10months time. So with the new 12V battery I am recharging the battery with 60 minutes in READY mode while I wash the car as shown in this video: kzbin.info/www/bejne/eZmQfWOAl8eEi8k I am monitoring the 12V battery with my voltmeter. If the voltages do start to drop below 12V I have decided that I will go to a local garage (not a Toyota dealer) and get a Yuasa 12V battery fitted. From what I have read they are a much higher quality battery. I believe that Toyota dealers will only fit parts recommended by Toyota so a dealer will only fit the same low quality battery that is installed at the factory. It's such a pity because in a lot of ways my Yaris Mark 4 is the best car I have ever owned ... unfortunately at the same time it is also the worst car I have ever owned because of the 12V battery issue.

[@Helpful-Stuff]

@shreeshsaurya4203 The Yaris problems all seem to revolve around the poor quality Mutlu battery that Toyota fit. My car's 12V battery had degraded after just one failure to start because the new battery's voltage reading were about 0.5V higher than the old battery. A degraded battery is not unusable and will start your car most of the time but it is more likely to lose charge if parked and unused for a few days. If you do not want the inconvenience of another failure to start I would recommend that even after just one failure to start that you get a new 12V battery ... and if possible a Yuasa battery fitted by a local garage. Yuasa batteries have a much better reputation. I also would not trust the 12V battery tests that UK dealers carry out. Toyota Poland have admitted that there is a 12V battery problem with the Yaris. They have rolled out new test equipment and test procedures to all Polish Toyota dealers. They will replace any 12V battery that does not pass the new test procedures under warranty. motoryzacja.interia.pl/samochody-uzywane/porady/news-kupila-nowke-za-100-tys-zl-auto-nie-odpala-wiec-do-pracy-cho,nId,7305589 kzbin.info/www/bejne/e3nXmGtnoLJgfLc I do not know for certain but I don't believe that UK dealers have the new 12V battery test equipment.

[@user-ng2md3gg4z]

I have a 2015 Yaris Hybrid which I am very happy with. Very economical and reliable. I got it 2ndhand about 3 years ago. After about 6 months I did notice that it was tending to switch the engine on even when the car was stationary and seemed to rev fairly hard. Then it went flat overnight and I had to charge the battery to get it going again. As I have years of fiddling with cars in an amateur way, my first instinct was to measure the battery voltage with a multimeter and it tended to fall below 12 volts fairly regularly. So I decided to replace the battery which at that stage was the original one I think which made it 6 years old. Next decision was which battery to get. The orginal Yuasa battery was an AGM one and double the cost of a standard one. After a bit of research and examining the old battery I decided to replace it with an identical battery - and I was glad I did because the replacement was fiddly as it is under a bracket under the rear seat close to the HV battery. It cost £120 which is not cheap to my mind for a car battery but as the 1st one did 6 years, I thought that was OK. Anyway with the new battery I have had no problems at all and the car just generally worked better and stopped revving when stationary. I think this was caused by the computer always trying to charge the 12 Volt battery. I get really good MPG's - usually 65mpg. I think you can use a conventional lead acid battery in some hybrids but I think they have a current monitor fitted close to the battery to monitor the charging. I don't think my car has one as it has a AGM battery. The other issue with your car may be that there is a parasitic draw which may have little to do with the battery except it flattens it! There are quite a few YT videos on how to find a parasitic draw as they are pretty common.

[@Helpful-Stuff]

I owned a 2018 Yaris Mark 3 Hybrid before I bought the 2022 Yaris Mark 4 in the video. The 2018 Yaris started reliably for 5 years even during COVID lockdown when it was only used once a week to go to the supermarket. I had a LandCruiser and it failed to start when the LandCruiser was 12 years old with the original factory fitted batteries. (The LandCruiser has two 12V batteries). The AA man told me he was amazed that the 12V batteries had lasted that long. He jump started me and told me that I MUST get new batteries immediately because the AA would not come out and jump start me again!!! From this discussion with the AA man I think you did well to get 6 years out of the 12V battery in your Yaris. I believe that an AGM battery is used in the Yaris because it is not safe to have a lead-acid battery inside the passenger compartment because of the fumes from a lead-acid battery are dangerous. So its good that you changed the 12V battery for an identical one. It's really interesting what you are saying about the car revving when stationary to charge the 12V battery. If I hear this in my car I will change the battery ... but hopefully my voltmeter will allow me to see the voltages dropping before I hear the engine revving. Since my 12V battery went flat I have discovered that a flat 12V battery is VERY common in the Yaris Mark 4. There is an 88 page (!!!) discussion on the Toyota Owners Club website www.toyotaownersclub.com/forums/topic/217673-12v-battery-maintenance-issues-etc/ and even a 27 page discussion on Toyota's website mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/ Low mileage Yaris owners in particular are very likely to suffer from a flat 12V battery. I do UK average mileage but still my car failed to start after a single day without use. I have a theory that Toyota screwed up trying to update my car to fix a safety related problem with the e-Call system so I don't think my problem was caused by low mileage but by Toyota's poor systems for doing an OTA kzbin.info/www/bejne/jqi8aKBprdCsmK8 There isn't a parasitic draw fault on my car ... Toyota have designed a flawed 12V system on the Yaris Mark 4. Unfortunately, Toyota just tell owners that it is their fault for not driving enough miles. Its corporate arrogance that will cost Toyota in the long term. Toyota HAD a reputation for building reliable cars .... they do not have that reputation any more. In order to ensure that my car does not fail to start again I ... (1) Charge the battery in READY mode for an hour each week while I wash the car kzbin.info/www/bejne/eZmQfWOAl8eEi8k (2) Use a solar trickle charger when the car is going to be parked on sunlight for more than 3 or 4 hours as recommended by my dealer kzbin.info/www/bejne/mYTJmp5qrt6LnNE (3) Purchased a NOCO GB20 jump starter which I keep behind the passenger seat just in case the above do not work I think my Yaris Mark 4 is the best car I have ever owned ... but unfortunately it is also the worst car I have ever owned. And after owning Toyota's since 2005 ... it is my last Toyota. It's just a case of how long can I put up with wondering if the car will start each morning....

[@johnkeepin7527]

Similar issue here. Running a Mk4 after a Mk3, and it’s just over a year old. This winter, when we had some cold weather with overnight temperatures around -6 °C, with a couple of weeks of low running hours, I fell foul of the battery being too low for it to start, so a ‘jump start’ was required. The fault messages are confusing, and actually says nothing about the real problem! The current Toyota online bumf does recommend a minimum ‘power on’ time of at least 20 minutes a week - a bit close to the bone, perhaps. Worth noting that the battery capacity ratings quoted are often done without stating at what temperature they are valid at. It’s at least 20 °C, but around -5° it’s a lot less. Lead Acid batteries are temperature dependent, so no surprise as to when the fault occurred this year. Depending on what you have in your Yaris, it’s possible that it draws more currant than the older one did. Mine is the Excel model, and has the TAS600 system, and it’s got the MyT gadget in service - albeit with the extra gadgets that are available, such as remote start. However, it does communicate with my phone, and presents sat nav related results, fuel consumption etc that way. I suspect that too much use of this can draw down the 12V, on top of the burglar alarm and the key detector kit etc. If you have a suitable clamp device for the battery cabling ( a bit awkward to use given where it is, under the back seat), you can have a go at measuring what the minimum is with almost everything off. You can tot up the minimum Ah draw then, and compare it with the battery rating. Not a good idea to leave it parked somewhere awkward for a couple of weeks unless it was fully charged on arrival, some might say. Keep a jump start device close to hand in that case, if it happens.

[@Helpful-Stuff]

I have got a 2022 Yaris with the Tech pack which includes the head up display and Smart Connect Multimedia system (which from Googling I think is the TAS600 system that you mentioned). The only non-factory fit kit I have got is a voltmeter plugged into the accessory socket ... more info about the voltages I am seeing in this video: kzbin.info/www/bejne/Zp-8laGEi8ypgKs My car failed after a single day without use and does UK average mileage. My dealer's original position was that I am not doing enough mileage - which I believe is Toyota GBs standard position when talking to customers with a car that failed to start. I believe I do sufficient mileage to keep my 12V battery charged kzbin.info/www/bejne/maW7daF_btqoj6s The factory fit 12V battery is rated at 35Ah. I parked my car about 3pm on Tue 24-Oct and then tried to start it at 9am on Thu 26-Oct which means it was parked for about 42hours. So for a 35Ah battery to be drained there must be a parasitic current draw of 35 / 42 = 0.8A for 42 hours ... I do not know the parasitic current draw of my Yaris but a typical modern car is just under 0.1A so I don't think it is possible for normal parasitic current draw to have flattened my 12V battery when parked for a single day. However, something flattened my 12V battery in 42 hours ... so there may have been some sort of unusual parasitic current draw. My current theory is that Toyota tried to do an OTA update to fix a safety related issue with the e-Call system: kzbin.info/www/bejne/jqi8aKBprdCsmK8 I am talking to Toyota GB customer services about this theory. Toyota GB's current response is that the e-Call system was updated by Toyota Europe ... so Toyota GB have no information on the date when the e-Call OTA update was done and they are unable to investigate !?!??!?!?! I found this page on Toyota's website that recommends 60min per week in READY mode. You may also want to have a quick scan through some of the 27 pages of discussion of people with the 12V battery problem. mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/ I combine my 60mins per week in READY mode with a weekly car wash kzbin.info/www/bejne/eZmQfWOAl8eEi8k I think this 92 page discussion on Toyota Owners club website shows just how widespread this problem is... www.toyotaownersclub.com/forums/topic/217673-12v-battery-maintenance-issues-etc/ My dealer has been very helpful and they have fitted the ODB cable free of charge so that I can easily plug a solar trickle charger in. kzbin.info/www/bejne/pWmwnHmLhcuXrLM I plug this in regularly ... not every day ... but most days especially if it is sunny. So I have got both "belt and braces" to try and avoid my 12V battery going flat again... - solar trickle charger plugged in regularly - weekly 60minute charge + car wash - NOCO GB20 jump starter stored in my car just in case !!!

[@nigelwoodford4040]

Hi Like the rest of you my 23 reg Yaris Hybrid fails to start with NO warning ! Unfortunately I bought a top spec model and the dealer added cameras front and back as a deal sweetener after a 14 month delivery wait. I wonder which (non starting) features drain the 12v battery the most - Electric mirrors? Cameras? Keyless entry? Clearly the battery and trickle charging on this car isn't 'fit for purpose' Monitoring the voltage is also my short term work around but unless Toyota solve this without expecting owners to 'go for an hours drive' at least once a week I will look for a replacement car from one of Toyota's competitors.

[@Helpful-Stuff]

From all the comments and a lot of reading I think the problem is the poor quality Mutlu battery that is factory fitted. After 5 months of complaining to Toyota GB I got a replacement battery. Unfortunately it is another Mutlu. My original battery lasted 10 months 6,000 miles and after 1 day without use my car would not start. I have zero confidence that my new battery will last any longer. If my car fails to start again I will go to a local garage and ask them to fit a Yuasa battery. I have read a lot of comments from people who have changed to a Yuasa and solved the problem. I do not drive the car for 1 hour. I wash my car with the car in READY mode. I think this is actually more effective at charging the 12V battery than driving the car for 1 hour. kzbin.info/www/bejne/eZmQfWOAl8eEi8k As I mentioned above, I have got a new Mutlu battery since I made this video. I am now seeing voltages in the range 12.0V to 12.5V. Yesterday I drove 130miles non-stop. Today I was expecting to see a voltage of 12.4V or maybe 12.5V when I started the car but instead I saw 12.0V ... so over 3 hours driving the day before and the 12V battery was at the lowest voltage that I see. However, the day after a car wash + recharge in READY mode I normally see 12.3V or 12.4V. So my conclusion is turning the car on for 1 hour and letting it just sit in PARK is the best way to charge the 12V battery. Washing the car passes the time while the car is recharging. Wow a 14month delivery wait ... I ordered in 2022 an Excel with Tech pack and I "only" had to wait 9 months !!! I think the cameras will add to the battery drain but the root cause of the problem is the 12V battery.

[@christopherpeters4815]

I have a Yaris Cross and had repeated problems with the 12V battery dying on me. Admittedly I don’t do many miles but complained to Toyota Head Office that I was never asked how much mileage I do and that I would have to drive aimlessly for 1 hour a week. In the end Toyota replace the battery free of charge with what they told me was a better spec one. So far so good.

[@Helpful-Stuff]

You do NOT need to drive for 1 hour a week to charge the 12V battery. There is no alternator in a hybrid - the 12V battery is recharged from the main traction battery whenever the car is in READY mode - the car can be stationary (in PARK) or moving. I combine a weekly 1 hour charge with a car wash because I don't want to sit in the car for 1 hour a week doing nothing. The video shows some tips for doing this: kzbin.info/www/bejne/eZmQfWOAl8eEi8k I also complained to Head Office and after 5 months I also got a replacement battery. I was told some blatant lies during the email exchanges that in my eyes has further degraded the Toyota brand. Toyota Poland have admitted that there is a problem with the 12V battery. They have new test equipment and procedures and will replace batteries that fail the new test under warranty. kzbin.info/www/bejne/e3nXmGtnoLJgfLc Toyota GB are still fobbing off customers with the line that "it is your faulty for not driving enough miles". It is NOT the customers fault it is Toyota's fault for using a poor quality battery supplied by Mutlu. My Toyota dealer have given me another Mutlu battery ... I suspect that your replacement battery is also a Mutlu battery ... but its possible that your dealer has decided to put a Yuasa battery in your car but this will be against Toyota GB policy. The Yuasa battery is a better quality battery and I have read that people have generally found that this has resolved the problem. If my new battery fails to start my car I am going to a local garage to get a new Yuasa battery. Around March or April-24 Toyota GB issued a bulletin about the 12V battery problem. Dealers are meant to check your car against the list of cars in the bulletin. If your car is on this list then the battery will be replaced free of charge with no need to test the battery in your car. I discovered that my car was listed in this bulletin which is why Toyota GB suddenly agreed to change my battery. Its possible that your car is also on this list.

[@mwilson9701]

I have 5yr old corolla. When 12v battery low the theft alarm blare out - usually at night. Initially during lockdown when minimal use and recently when battery aging. No info on screen concerning 12v status. I used float charger over 1 week and only raised voltage from 11.8 to 12.4. So battery needed replacing. But till then able to stand 2 weeks without use no problem. Reason - an electric Renault Zoe which is used most of the time.

[@Helpful-Stuff]

I had a Yaris Mark 3 during lockdown and it started reliably being though it was only being used once per week. This is why I am so disappointed with my Yaris Mark 4 which failed to start after just one day without use when only 10months old with around 6,000miles on the clock. Hopefully a new battery will resolve your problems 🤞

[@roberthuntley1090]

My Lexus UX hybrid acts pretty similarly, although its worth highlighting that I see a different voltage in Park to Drive or Reverse. Does the Yaris behave in the same way? My figures with the hybrid system powered up are: 14.4 volts - The battery is being charged. 12.4 volts - The battery has reached full charge and is being floated (I only see this in D or R). 13.7 volts - The battery is fully charged but I'm in Park. I believe this is a slight overcharge to balance up the stronger and weaker cells. As such, I've taken to using Park more often at traffic lights and so on. Its also worth noting that its better to stick the car in Park for an hour than to drive it for an hour when charging the battery. PS - As an aside, I had the battery replaced a couple of week (it was about 5 years old). I had to have the car jump started back in 2020 and I think that took some live out of the battery. Cost just under £200 at Lexus main dealer prices so not too bad to restore confidence. The event that triggered me to change it was a reading of 9.8 volts at the instant to starting the hybrid system after the car had been parked for a week.

[@Helpful-Stuff]

Thanks for the information about the voltages that you are seeing in a Lexus UX Hybrid. Its interesting that they are broadly similar with the recharge voltage of more than 14V and when the battery is charged it drops to a lower voltage above 12V. Shortly after I made this video Toyota GB finally agreed to change my 12V battery under warranty. The voltages from the new battery are all about 0.5V higher than the voltage shown in the video. The new battery is nearly always above 12.0V ... it was less than 12.0V on two occasions in the last 8 months and both times it was 11.9V ... which is obviously only just below 12.0V. This confirmed to me that my old battery was not 100% healthy and should have been immediately changed under warranty. My dealers 12V battery test equipment showed that my battery was healthy ... so in my view Toyota's 12V battery test equipment is wrong. My view is confirmed by Toyota Poland who have admitted that their is a fault with the 12V system in the Yaris and they have rolled out new test equipment and procedures to all Polish Toyota dealers. Any battery that fails the new tests is replaced under warranty. motoryzacja.interia.pl/samochody-uzywane/porady/news-kupila-nowke-za-100-tys-zl-auto-nie-odpala-wiec-do-pracy-cho,nId,7305589 I think one of the problems is that the Toyota battery test equipment just showed "Healthy" ... I think what is actually needed is a percentage healthy figure. I think my old battery as a 10month old battery should have been 95+% healthy but in actual fact it was around 70% healthy. So it was healthy enough to start my car when I used it every day but I bet if I had parked it for a day or two it would have failed to start my car again. So it is a good job that Toyota GB did finally agree to change my old battery. I think you were absolutely correct to change your 12V battery after the 9.8V reading. I think a 12V battery's health is damaged when the voltage drops that low. A 12V battery is not that expensive but you can guarantee that if you did not change it the car would refuse to start when you are in a rush to get somewhere. If my car fails to start again I have decided that I am going to go to Halfords and get a Yuasa battery fitted. This is a 45Ah battery compared to the Mutlu 35Ah battery that Toyota fit. The Yuasa battery is also apparently a much better quality battery. I have read comments in forums that people say that the Yuasa battery solves the Yaris 12V battery problem 👍 I have noticed that when I put the car in PARK after driving the voltage is always above 14V even if I had looked at it shortly before parking and it was below 14V. So I suspect that you are correct and that when you put the car in PARK the voltage is increased to above 14V to charge the battery. In the video I show the voltage when I washed the car in READY mode and the car was in PARK for 1 hour. So putting the car in PARK may temporarily increase the voltage to more than 14V to recharge the 12V battery but the video shows that the voltage will drop when the 12V battery is fully recharged. I have never looked at the voltage when reversing ... I will have a look over the weekend.

[@roberthuntley1090]

@@Helpful-Stuff Thanks for the comprehensive reply. Interesting stuff.

[@daviddawson9099]

That is very interesting. Just checked my son in laws Yaris as it failed to start. It was measuring 9 volts with the car turned off. He had been jump started by the RAC and had driven back to my house. There was a strong smell or rotten eggs which I suspect was hydrogen sulphide. I read online this could be due to a battery failing. Anyway took the battery off and the voltage measured 12 volts with no load. The RAC man was unsure what the smell was and suggested the catalytic converter makes a similar smell when faulty. Anyway I was considering recharging the batter then refitting it, Once out of the car it became evident the smell was most likely from the battery. Also on further inspection I noticed the sides of the battery were budging. So will be ordering a new battery and hopefully will just to be able to replace it no problems. I had a problem with my Auris during covid with the battery going flat due to low usage and leaving the tailgate open draining the battery. Anyway after a recharge and refitting that has been ok since. Shame they can not fit a small solar panel to keep the battery topped up when the car is not been used. I had considered getting one if leaving the Auris standing but since covid touch wood it has not been a problem.

[@Helpful-Stuff]

You way want to have a look at this video that I have made about a report on a Polish website that Toyota have accepted that there is a problem with the 12V battery in the Mark 4 Yaris. If your son in law's Yaris is still under warranty he may be able to get the battery changed under warranty. kzbin.info/www/bejne/e3nXmGtnoLJgfLc When my car failed to start the AA man measured the voltage at 9.45V. My car was only 10 months old and had not been used for one day. I drive around 7,000miles per year so my car is not a low mileage car. So in my view it should not have failed to start. kzbin.info/www/bejne/Y4bOo4itpdCYhq8

[@daviddawson9099]

@@Helpful-Stuff Thanks the battery was not under warranty as over 5 years old. Anyway looked up a replacement and found just as cheap to buy one with same spec from local Toyota dealership. I got a 10 percent discount which made it comparable. Anyway new one came was same spec but physically slightly smaller. It still fitted in ok as height and depth were the same just slightly less wide. There was a plastic cover that is stuck in the car that fitted over the battery and a small hole in the cover and battery to fit the small tube for any gassing off from the battery. Anyway fitted and tried all working ok no resetting of anything and all seems to be back to normal. Ordered via the car registration and only one offered. Did find one same make but slightly bigger capacity and a touch wider so decided to go with the Toyota offered one just under £160 not cheap but well car would not work without one.

[@Helpful-Stuff]

I think your son-in-laws car is a 2019 or earlier so it is a Yaris Mark 3. I owned a Mark 3 from 2018 to 2022 and it started reliably in the almost 5 years that I owned the car - even during COVID when I only used the car once per week to go to the supermarket. 12V batteries don't last forever so your new 12V battery should give you another 5 years of reliable starting 👍 All the videos I have been making about the 12V battery problems are for the Yaris Mark 4 ... my car failed to start after 1 day without use!!! In my experience your son-in-laws Mark 3 is a better car in terms of starting reliability than my Mark 4!!!

[@daviddawson9099]

@@Helpful-Stuff Yep it is a mark three. I actually have had trouble with my Auris tourer during corvid. I left the rear open and the internal light drained the 12 volt battery. The battery was ok still and after a jump start when back at home I took it off and recharged it. Still ok now with the same battery. I think though especially newer cars with more electrical draw for things such as alarms when the car is off there is a vulnerability there. This can be a particular problem for low mileage users and something that should be addressed by Toyota. Perhaps someway of putting the low voltage battery on charge automatically when it gets low prior to it going completely flat. Or a solar panel to keep it charged up. Certainly when it happens for the first time it is perturbing as the display can do random things often showing up the engine warning light. It must be a known problem to Toyota and not beyond them to come up with a solution.

[@Helpful-Stuff]

All Hybrids and EVs from all manufacturers have the 12V battery problem because they only need a small 12V battery because there is no starter motor ... but modern cars draw a lot of current when switched off and parked and this can drain the small 12V battery so that the car will not start after being parked for several days. And as you say this is more likely to happen to low mileage owners. After the AA had jump started my car my HUD wasn't working. It wasn't broken but an engineer had to stick a laptop into the OBD port and reset something to get it working again. From what people have said I think a failure to start affects the dashboard display and the electronics slightly differently in each car!!! Kia and Hyundai have developed the 12V Reset button. The 12V battery voltage is monitored when parked and if it drops below a certain voltage the 12V supply is turned completely off so that when you return to the car you press the 12V reset button and then the car will turn the 12V back on and the car will start because the 12V circuits were turned off and this stopped the battery from going flat. kzbin.info/www/bejne/aZyahIaAmsh3i8k I was watching a video about the MG app and this shows that the 12V voltage can be monitored in the app. Toyota are not really doing anything to help owners to monitor the 12V battery. There isn't even a 12V voltmeter on the dashboard. Toyota's response to the Yaris' 12V problem has been disappointing. Like you I can think of several possible solutions ... it would be nice if Toyota did something to help us manage the 12V battery with voltmeters on the dash and/or the app and maybe something like Kia/Hynudai's 12V reset button or a built in solar panel or maybe a free NOCO Jump starter with a new car!!!!

[@petertysoe3832]

Couldn't the problem be solved by a software tweak that throws the relay on the traction battery, to recharge the 12v battery, occasionally, when the car is parked up? Say for 30 mins at 2:00 am?

[@Helpful-Stuff]

A characteristic of all hybrids from all manufacturers is that they use a small 12V battery and if you leave it for 2 weeks in an airport car park while you are on holiday then the battery will probably be flat when you return from holiday. My Yaris Mark 3 Hybrid which I owned 2018 to 2022 started reliably for 5 years even during COVID when it was only used once per week. However, my Yaris Mark 4 failed to start when it was only 10 months old after ONE day without use. There is clearly a major problem with the Yaris Mark 4 which is a LOT worse than the normal characteristic of a Hybrid with a small 12V battery. I believe Toyota Europe have now finally recognised and will test and replace the 12V battery under warranty. kzbin.info/www/bejne/e3nXmGtnoLJgfLc I think your suggestion is a potential solution to the generic problem with Hybrids and the small 12V battery .... but in the case of the Yaris Mark 4 I think it would mask the root cause of the problem which is a bad choice of 12V battery fitted at the factory. Kia and Hybrid have come up with something called the "12V reset" button to avoid the 12V battery going flat in their Hybrids kzbin.info/www/bejne/aZyahIaAmsh3i8k I think Toyota and all manufacturers need a solution to the 12V battery problem because a lot of people are saying they would prefer to go back to a petrol/diesel car which starts reliably.

[@sinnombrefoto]

Is the first thing i thought today when my parents Yaris didnt start.. i couldnt belive that a hibrid car, can run out of battery but having another battery system pretty full.. sound pretty weird... this engineers, too many studies, but a no common sense?

[@Helpful-Stuff]

@sinnombrefoto I have read a lot of articles and discussions about the Yaris Mark 4 12V battery problem and I think that the problem is a very bad choice of 12V battery. The factory fit Mutlu 12V battery is a poor quality battery. I will replace mine with a Yuasa 12V battery if my car fails to start again. Because Toyota dealers will only use Toyota recommended parts I will have to get my local garage to get a Yuasa battery fitted. Toyota Poland have got new 12V battery test equipment and test procedures and they will replace any 12V battery that fails the new tests under warranty. kzbin.info/www/bejne/e3nXmGtnoLJgfLc I find it totally unforgivable that Toyota GB's policy has been and may still be to blame customers for not driving their car enough. It is Toyota's fault - their engineers chose the Multu battery ... it is Toyota's fault. It is also totally unforgivable that some Toyota dealers are charging customers £140 to recharge and test the 12V battery. The tests are the old tests that Toyota Poland no longer use so if you pay £140 to have the 12V battery tested then it will probably pass the tests even though the battery would fail Toyota Poland's new tests. The situation is a total mess of Toyota's making. I have owned Toyota's since 2005 but my next car will not be a Toyota.

[@Forde-Photos]

Thanks a great video .I have had my Yaris for 5 months and no battery problem so far .I must get a voltmetre like that to keep an eye would you have a link to the type you used in the video.

[@Helpful-Stuff]

This is the link to the one that I bought on eBay ... but there are loads of similar ones from Amazon and other websites. www.ebay.co.uk/itm/266196406007 Cross fingers that you manage to avoid the 12V battery problem. The other things I am doing to hopefully avoid having another failure to start: - a weekly car wash + charge battery kzbin.info/www/bejne/eZmQfWOAl8eEi8k - solar trickle charger kzbin.info/www/bejne/pWmwnHmLhcuXrLM - I have also bought a NOCO Jump Starter I live in the middle of the countryside and I am very dependant on my car which is why I am doing my best to avoid having another failure to start. The Yaris is both the best car I have ever owned ... but at the same time it is the worst !!!

[@Forde-Photos]

@@Helpful-Stuff Thanks I also live in the sticks .I have brought a jump starter so will look up the meter :)

[@raychez1095]

My mazda 2 hybrid 12v battery has gone flat twice once this August then again this dec.There is definitely a fault and somethings draining the battery.I charged it up overnight and its going to the dealer for the week so they can test it.Its only 2yr old and I am not happy with it .

[@Helpful-Stuff]

I totally understand your frustration. Unfortunately, this happens to so many Yaris and Mazda 2s that I am almost certain they will not find a fault with your specific car. It is a design fault that Toyota refuse to accept and instead insist on blaming customers for not driving enough miles which is totally unacceptable!!! The problem is the 12V Mutlu battery. Some people have resolved the problem by fitting a Yuasa battery at Halfords or other non-Toyota garage. The Yuasa battery is a better quality battery but also is rated at 45Ah rather than the 35Ah of the Mutlu battery. This means that the Yuasa battery can hold more charge so it will be longer before the 12V battery goes flat. I suspect that if they do anything your Mazda dealer will replace the 12V battery but because they are a dealer they will replace with another Mutlu battery. In my view this will give you a few months of trouble free starting but you will eventually get another failure to start because it is another Mutlu battery. My Yaris failed to start when 10months old with 6,000miles on the clock and ONE day parked. My dealer tested the battery and said it was OK. I complained to Toyota GB and after 5 months(!) I did get a replacement Mutlu battery. However, I now have a 12V battery management routine to ensure that I never get another failure to start (1) Recharge & wash the car every 7 to 10 days with the car in READY mode to allow the car to charge the battery. Video with some tips on how to do this... kzbin.info/www/bejne/eZmQfWOAl8eEi8k Toyota recommend that low mileage Hybrids are run for 60minutes per week in READY mode mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/ I don't consider my 8,000miles per year as low mileage but since my car failed to start I guess it must be low mileage !?!?!? (2) Voltmeter fitted to accessory socket to monitor the 12V battery voltage. This video explains how to use this to see the 12V battery voltage and not the recharging voltage. kzbin.info/www/bejne/Zp-8laGEi8ypgKs (3) Solar trickle charger is fitted whenever I do not use the car for 24 hours or more kzbin.info/www/bejne/mYTJmp5qrt6LnNE My personal routines have changed and there are now very few days when I do not use the car so I do not use the solar trickle charger very often. The Service Manager at my dealer told me that customers who only use their car 2 or 3 days per week have reported that this works. (4) Carry a NOCO GB20 jump starter behind the passenger seat just in case the above does not work and my car fails to start I am not happy at having to do this but I have been doing this for about 13 months now and it is working ... I have not had another failure to start 👍 A bit of background that I have discovered .... Hybrids and EVs do not have a starter motor so they do not need a big 12V battery that can supply lots of current to the starter motor in a petrol/diesel. Hybrids and EVs only need a small amount of current to power the computers so they can have a small 12V battery which is great for saving space and weight and improving fuel economy. The problem is that all modern cars use a lot more current when parked than a car of 20 years ago. So the small battery has to supply a lot of current when the car is parked and the 12V battery is not being recharged. This means that if you Google you will find lots of stories about failures to start for all EVs and Hybrids from all manufacturers because the 12V battery has gone flat. The big difference is that most of these stories are about people who have left their cars in an airport car park or whatever for 2 or 3 weeks while on holiday. Unfortunately the Yaris/Mazda 2 can experience a failure to start after just 1 day parked (as happened to me). Personally I can accept a failure to start after 2 or 3 weeks in an airport car park ... not not after 1 day. Thanks to a comment from a Polish viewer I know that Toyota Poland have admitted that there is a fault with the Yaris. They have rolled out new test equipment to the Polish dealers and any battery that fails the tests with the new equipment will be replaced under warranty. I do not know if Toyota GB or Mazda dealers have this new test equipment. motoryzacja.interia.pl/samochody-uzywane/porady/news-kupila-nowke-za-100-tys-zl-auto-nie-odpala-wiec-do-pracy-cho,nId,7305589 My dealer tested my 12V battery after my failure to start and said it was healthy. However, when I compared the voltage of my old and new batteries measured with my accessory socket voltmeter I know that my battery was not 100% healthy and should have been changed immediately my car failed to start ... not 5 months later. Unless your Mazda dealer has the Polish test equipment I would not trust the result of your dealer's battery test. My battery was not 100% healthy after one failure to start. So, I believe that even one failure to start shows that your battery is not 100% healthy which means that another failure to start is likely ... then you have another failure to start which means that the 12V battery is even more degraded so another failure to start is very likely ... so the more failures to start you have the more frequently your car will fail to start. If your dealer will not change the battery then I recommend that you go to Halfords or other independent garage and get a Yuasa battery fitted. If I get another failure to start I will be getting a Yuasa battery fitted asap!!! I have also taken the decision to sell my Yaris in 2025. Although I really like the car .... this constant worry about will it or won't it start each morning is very annoying and I am fed up with it!!! ... so the car has to go and despite have owned a Toyota since 2005 I will definitely NOT buy another Toyota ... or Mazda 2. Incidentally my previous car was a Yaris Mark 3 which I owned from 2018 to 2022 and it started reliably even during COVID lockdowns when it was only used once per week to go to the supermarket. So this is a Yaris Mark 4 problem. I have just scrolled back ... that's a very long comment!!! I hope it is helpful.

[@MrBrownstick]

It happened to my Prius after a year. I just got a new battery.

[@Helpful-Stuff]

I have never owned a Prius so I have no experience of the 12V problem in a Prius. The Yaris has a specific problem related to the Mutlu battery. This is a poor quality battery that means that the Yaris Mark 4 is very likely to fail to start because the battery has lost charge. My 10 month old car with around 6,000 miles on the clock failed to start after just one day parked!!! Toyota GB agreed to change my 12V battery 5 months after my failure to start. I have got a new battery but it is the same Mutlu battery that failed after 10months. I have no confidence that it will last longer than the last battery unless I "look after" the battery by: - washing the car in READY mode every 7 to 10 days to keep the 12V battery charged kzbin.info/www/bejne/eZmQfWOAl8eEi8k - connect an AA Solar Trickle Charger if the car will not be used for 24hours or more kzbin.info/www/bejne/mYTJmp5qrt6LnNE - monitor the 12V battery voltage every time I start the car kzbin.info/www/bejne/Zp-8laGEi8ypgKs - keep a NOCO GB20 jump starter under the passenger seat. Its a real pain. Its a good job that once the car has started I think that it is the best car I have ever purchased otherwise I would have sold it!!! If my car fails to start again I am going to get a local garage to fit a Yuasa battery which apparently is a much better battery and has solved the problem for most people.

[@MarianA-vu8tb]

U could buy a solar panel charger that connects to OBD port so it can charge the 12v battery even when ignition is in the off position, put the panel on the dash. also u could upgrade the battery with an AGM battery and possibly with a bigger CCA capacity battery space permiting.

[@Helpful-Stuff]

Both good suggestions .... My dealer recommended the AA Solar Trickle charger and they fitted the cable to the OBD port so that I can easily plug the solar panel in above the dash rather than getting down on my knees to plug it in below the steering wheel. I have made a couple of videos: kzbin.info/www/bejne/mYTJmp5qrt6LnNE AA Solar Trickle Charger kzbin.info/www/bejne/pWmwnHmLhcuXrLM Dealer fitted cable I managed to get Toyota GB to change my 12V battery 5 months after my car failed to start. Unfortunately they have changed it for the same Mutlu battery that was fitted to my Yaris when new. I have absolutely zero confidence that this battery will last longer than the 10 months that the factory fitted battery lasted. I have read that lots of people have solved the problem by going to a non-Toyota garage and getting a Yuasa battery installed. There is a Yuasa battery that fits the small space beneath the Yaris' rear seat. The Yuasa battery is 45Ah. I believe that the Multu battery is 35Ah. Since I got a new Multu battery out of Toyota GB I want to get a few more months use out of it before I replace it with a Yuasa battery early next year.

[@TheFallenAngel00]

​@@Helpful-Stuff a question, I heard that changing the battery by own or by a third part and not by the dealer officer can waste the warranty of the hybrid because the obd can detect the change of battery and the hybrid check doesn't pass so the warranty is not extended? If you change the battery at third part let we know if causes this problem on the annual maintenance, or if you chose to do with the dealer then can you watch what they do to let the hybrid check to pass whole tests? Thanks

[@Helpful-Stuff]

In the UK (and I think in the EU) it is illegal for car manufacturers to force you to service or maintain your car at a dealership in order to maintain the warranty. My car's manual states "For replacement of the 12-volt battery, contact any authorized Toyota retailer or Toyota authorized repairer, or any reliable repairer." .... Note the "any reliable repairer" - so you do not need to use a Toyota dealership. There is also a section in the car manual that provides instructions on how to change the battery so it is also OK to change the battery yourself. There is also guidance on the specification of the battery but it does not specify that the battery must a Mutlu battery (this is the battery that Toyota install at the the factory). ===Copied from my car's manual=== When replacing the 12-volt battery ●Use a Central Degassing type 12-volt battery (European Regulations). ●Use a battery that the case size is same as the previous one, 20 hour rate capacity (20HR) is equivalent or greater, and performance rating (CCA) is equivalent or greater. Check the label on top of the battery for the battery size and specifications (ex. LN0, 35Ah, 264A). • If the sizes differ, the 12-volt battery cannot be properly secured. • If the 20 hour rate capacity is low, even if the time period where the vehicle is not used is a short time, the 12-volt battery may discharge and the hybrid system may not be able to start. ●Use a ventilation type calcium battery ●Use a 12-volt battery with a handle. If a 12-volt battery without a handle is used, removal is more difficult. ●When removing the 12-volt battery: P.328 ●After replacing, firmly attach the following items to the exhaust hole of the 12-volt battery. • Use the exhaust hose that was attached to the 12-volt battery before replacing and confirm that it is firmly connected to the hole section of the vehicle. • Use the exhaust hole plug included with the 12-volt battery replaced or the one installed on the 12-volt battery prior to the replacement. (Depending on the 12-volt battery to be replaced, the exhaust hole may be plugged.) ==== So, in the UK (and I believe the EU) you can change your 12V battery at any car repairer or even at home and it will not affect your warranty provided you use a 12V battery that meets Toyota specification.

[@TheFallenAngel00]

@Helpful-Stuff Ok, because there are many cases that by changing the 12v battery by ourself, the obd system at annual maintenance says in sometime the battery was disconnected, so this cased so manu the problem of out of warranty, because it doesn't pass the hybrid check that has warranty on the hybrid system, and the dealer said that if I want the 10 years warranty I have to do annual maintenance at the dealer with hybrid check. Maybe the battery once replaced, it needs to be registered to through obd to the car system? Idk, thanks for the answer.

[@FactsTrumpFeelings.]

I had the pleasure of my Yaris failing to start, cars 2 years old., apparently battery needs changing, but I’ve gotta pay, apparently it’s wear and tear, be interesting to know what warranty they give me on the new battery, and what the manufacturer warranty is..

[@Helpful-Stuff]

Toyota are meant to be rolling out new test equipment & procedures for the 12V battery across Europe (which I assume includes the UK) and if a 12V battery fails then the 12V battery will be replaced under warranty. I have put more details in this video and there is a link to the original article in the video's description. kzbin.info/www/bejne/e3nXmGtnoLJgfLc It would be really interesting to know if UK Toyota Dealers have got new test equipment and using the new test procedures .... it would be great if you could ask your dealer and then leave a comment.

[@ciarangh]

I have a yaris design 21 plate, left my car for 11 days this month while i was away on holiday. came back, it started up no problem. I feel like the only one who's not having issues with the MK4? i also don't do that many miles, maybe 100 or so a week

[@Helpful-Stuff]

There must be something that you are doing right that the rest are doing wrong!!! I am doing a few more miles than you but my car failed to start after 1 day without use kzbin.info/www/bejne/Y4bOo4itpdCYhq8 ... I find it hard to believe that you were able to leave your car for 11 days without use!!!! I am currently making very slow progress with a complaint with Toyota GB Customers Services because I believe my problem may have been caused by a botched attempt by Toyota to do an OTA to fix a safety recall related to the e-Call system which drained my 12V battery. kzbin.info/www/bejne/jqi8aKBprdCsmK8 I had a Yaris Mark 3 which started reliably even during COVID lockdowns when it was only used once per week. My Yaris Mark 4 failed start when it was only 10 months old after 1 day without use. My view is that Toyota have botched the design of the 12V system in the Yaris Mark 4 which means that the it is very easy for the 12V battery to be drained. I have read that some people have changed the factory fit 35Ah battery for a 45Ah battery at Halfords. Maybe Toyota should change the battery in all Yaris Mark 4s to 45Ah. I don't think that Toyota will admit that there is a problem because they would then need to fix every single Yaris they have sold and that would costs a lot. If it was safety related then they would be forced to fix the problem but it isn't safety related so their strategy is to blame customers for not driving enough!!! Toyota need to wake up and realise that it is THEIR problem .... and that the strategy of blaming customers is causing a LOT of bad feeling that will result in Toyota losing their reputation for building reliable cars. I doubt I will buy another Toyota after owning Toyotas since 2005.

[@robertmicallef2662]

i notice same low charge on my corolla which is about a year old. i sometimes charge it which fixes the problem for a couple of weeks. as its a 20hp engine the battery is at the back. i charge it directly through the battery terminals, would you suggest using the front jump starting location in stead ?

[@Helpful-Stuff]

My Yaris' 12V battery is located under the rear seat. The Owners Manual for my Yaris says that the 12V terminal under the bonnet should only be used for jump starting and should not be used for recharging the 12V battery. I have read that this is because the terminals under the bonnet connect to the DC/DC converter and not the 12V battery. The DC/DC converter recharges the 12V battery in a hybrid. If I want to recharge my Yaris' 12V battery using a charger I must connect the charger directly to the 12V battery under the rear seat. I have never done this. I keep my 12V battery charged by a washing the car with the car in READY mode every 7 to 10 days more details in this video kzbin.info/www/bejne/eZmQfWOAl8eEi8k I don't know anything about your Corolla but obviously both my Yaris and your Corolla use the same Toyota Hybrid system so its probably that same with your Corolla. I would certainly check your Owners manual before you connect a charger to the 12V terminal under the bonnet.

[@robertmicallef2662]

I have charged it a number of times using the battery terminals. But note that after two weeks its down to 18 % charge even if used nearly daily. Ill try your “washing way” and see how it goes

[@Helpful-Stuff]

If you are using your car almost daily and your battery drops to 18% then it is possible that your battery needs changing. Although I note in your fist comment you said that your car is only 1 year old so your battery should not need changing. However, my Yaris failed to start when it was only 10 months old after just one day parked and not used! My dealer tested my battery and claimed it was OK. I didn't believe them so I complained to Toyota GB and after 5 months of email discussion they agreed to change my 12V battery under warranty. A Polish viewer of one of my videos sent me the link to this article (use Google Translate) which states that Polish Toyota dealers have got new 12V battery test equipment and procedures. I suspect that UK dealers do not have the new test equipment or procedures used in Poland so personally I would not trust the results of a UK dealers 12V battery test. motoryzacja.interia.pl/samochody-uzywane/porady/news-kupila-nowke-za-100-tys-zl-auto-nie-odpala-wiec-do-pracy-cho,nId,7305589 In online discussion about the Yaris' 12V battery problem I have read that a lot of people have had a Yuasa battery fitted and this solves the problem in a Yaris. I think this is because the Yuasa battery is rated at 45Ah compared to the Mutlu battery used by Toyota which is a 35Ah battery. I also believe that the Yuasa battery is a better quality battery that the Mutlu battery and therefore able to hold onto its charge better. If my car fails to start again I will go to a non-Toyota garage (Halfords) and get a Yuasa battery fitted. I will not try to do a warranty claim at a Toyota dealer again because even if Toyota GB agree to another warranty claim I will still get the same Mutlu battery which is just not up to the job of starting a Yaris. Although I will have to pay for the Yuasa battery it will be worth it so that I know my Yaris will start! I don't know any details about the Corolla and its 12V battery - I don't know if it also uses a Mutlu battery like the Yaris but it may be worth going to a non-Toyota dealer and changing to a different make of battery - hopefully a better quality battery.

[@balwek2]

Very interesting video, I got Camry and the voltage 14.4 or 12.4 in READY. (Actual voltage check on battery 0.2V extra). The dealer say the dc to dc converter never failed yet. The charge cotrolled by computer, it does what it need to do. So the only option is a bigger suitable AGM battery. Actually in Supercheap Auto store the only battery will fit anyway with 640CCA AGM with vent hole, this battery suit for idle stop-start too. The toyota original is 355CCA. The discharge current checked 0.9A when the boot open and car is off, the remote control take it, if you have dashcam it's more. Do your math. OK 24 hours x 0.9A = 21.6 , If the car charge 6A only it takes 3.6 Hours to recharge daily????? (my Camry Charges 5~6A) It's Weird. Interestingly an EFB / AGM mode battery charger charges max 6A to start and when drop down to 2.5 A will go trickle charge 13.6V to prevent overcharging.... The Toyota may have the same idea for charging????

[@Helpful-Stuff]

Thanks for the information that there is a 0.2V drop at the accessory socket voltmeter compared to the voltage measured at the 12V battery terminals. I knew there would be a drop but it is good to put an actual measured figure on it 👍 I think that in a Hybrid relatively little current is required to switch the computers on & switch the car on but the computers do need a good voltage from the battery. I think the most important feature for a Hybrid's 12V battery is the Ah. I believe that the Yaris Mark 4 has a factory fitted 35Ah 12V battery. A UK company (Halfords) will according to their website replace the 35Ah battery with a 45Ah battery. If I get more failures to start I will be replacing the 35Ah battery with a 45Ah battery. This should mean that it will take several more days for the battery to go flat if the car is not used.

[@balwek2]

@@Helpful-Stuff I just research yaris Hybrid battery and this come up S46B24RC Century ISS Active Stop-Start and Hybrid Auxiliary batteries are specially designed to satisfy the fuel saving and emission reducing benefits of vehicles fitted with Idle Stop-Start (ISS) or Hybrid systems. The range incorporates innovative design features and advanced raw materials to deliver superior cycling performance, high charge acceptance for rapid recharge in between engine off modes, and the extra power to run on-board electrics whilst the engine is switched off.

[@Helpful-Stuff]

The description of the battery sounds good. I have just Googled and I believe it is a 45Ah battery which is better than the 35Ah battery factory fit battery. I would check the size ... there isn't much space under the rear seat for the battery. The first comment in this discussion on Toyota Owners Club says "Note battery tray will only accept a battery of L175xW175xH190" www.toyotaownersclub.com/forums/topic/212489-new-12-volt-high-power-battery-fitted/ The dimensions of the S46B24RC are Length: 238 Width: 128 Height: 202 Total Height: 227 ... so I don't think it will fit the battery tray in the Yaris. This video shows how to change the 12V battery kzbin.info/www/bejne/mZW3doiofdhsi8U

[@gerarddudot6978]

J’ai également, comme vous, un petit voltmètre, et je procède de la même façon. Je mesure également, de temps en temps, la tension de la batterie de 12 volts, dans la boîte à fusible du compartiment moteur. Cordialement

[@Helpful-Stuff]

Voyez-vous une différence entre la tension mesurée à l’intérieur de la voiture et la tension au niveau de la boîte à fusibles ? (Google Traduction)

[@naweedsadiq]

Do you keep the voltmeter plugged in at all times? I’m a layman and have no idea about cars, batteries and parasitic draw etc…just keen to know if it’s ok to leave the voltmeter plugged in when car is parked overnight.

[@Helpful-Stuff]

I bought my voltmeter November 2023 and plugged it in. It's now October 2024 and it is still plugged in. My 12V battery has not gone flat during that time. So yes ... you can leave the voltmeter plugged in when the car is parked overnight. For the record my Yaris failed to start in October 2023 and I bought the voltmeter about a month later.

[@naweedsadiq]

@@Helpful-Stuff thank you. Your videos have been so helpful. I will likely try to get the 45ah battery a few folk gave mentioned as opposed to the 35ah which is likely in the car.

[@Helpful-Stuff]

The 45Ah that other people have fitted is made by Yuasa. It is obviously beneficial that the Yuasa battery has a bigger capacity than the factory fitted battery but I believe that the Yuasa battery is also a better quality battery. So a better quality battery with a bigger capacity should mean that your Yaris will not fail to start. I think I should mention that if you are going on a long summer holiday for several weeks then even with the Yuasa battery there is still the possibility that the battery will go flat after multiple weeks parked and your car will not start. The solar trickle charger plugged into the OBD port while you are on holiday will prevent the 12V battery from going flat. (I read a comment the other day from somebody who had successfully used the solar charger while on holiday for several weeks and their Yaris started OK 😀) However, with the Yuasa battery you should not get a fail to start after just ONE day parked ... which is what happened to me!!!

[@naweedsadiq]

@@Helpful-Stuff thank you. Yeah I got the Yuasa battery from Halfords and they installed it for me. Peace of mind as car is predominantly used by my son. I have the old Mutlu battery in the boot of the car and yeahs it’s 35ah and a much lower capacity compared to the Yuasa battery.

[@subwooferroads]

Can't you put a new 12 voltage battery with longer amp hours.

[@Helpful-Stuff]

Apparently Halfords will fit a 45Ah battery to replace the factory fitted 35Ah battery. When my Yaris failed to start and was taken to my dealer by the AA my dealer recharged the battery and recommended I buy a solar trickle charger ... so I bought one. I then Googled and started to read just how common this problem is with the Toyota Yaris Mark 4 .. there is an 88 !!! page discussion about this issue on the Toyota Owners Club. One common recommendation is to buy a NOCO jump starter ... so I bought one. Toyota recommend sitting in your car once a week for an hour with the car in READY mode to charge the 12V battery from the traction battery. Somebody on the owners club said he washed his car while it is charging to avoid sitting in his car and wasting an hour. I typically wash my car every week to 10 days so I started doing a weekly car wash + charge ... this is a "free" solution to me because I am going to wash my car anyway. I then read that some people are changing the 35Ah battery for a 45Ah battery at Halfords. I had already bought a NOCO jump starter and a solar trickle charger so I didn't really want to spend more money fixing Toyota's design problem. However, if the weekly wash + charge and the regular (but not daily) use of the solar trickle charge don't keep my 12V battery charged ... then I will be going to Halfords to get a 45Ah battery fitted. To be totally honest I feel very bitter about the way Toyota are handling this problem. It's a Toyota 12V design error that Toyota should fix but they won't because the cost of changing the 12V battery in all Yaris Mark 4 is too expensive. Toyota's reputation for reliable cars has trashed by the Yaris Mark 4. Incidentally I keep typing "Mark 4" because I had a Yaris Mark 3 for 5 years ... and the Mark3 started reliably for 5 years even during COVID lockdown when it was only used once a week. So Toyota can design a Hybrid that will start reliably ... but unfortunately the Yaris Mark 4 will not start reliably.

[@subwooferroads]

@@Helpful-Stuff wouldn't bother me to be fair I would go and buy the longest 12 volt amp hour battery I could fit in it

[@anonymousgoat107]

I'm curious to know whether your mpg has gone down because you're now needing to keep the car on to recharge this battery once a week?

[@Helpful-Stuff]

No .. I haven't noticed any change in my fuel consumption or the amount of fuel that I am buying. The petrol engine is only idling so the fuel consumption is very low. I do take precautions though by turning the heater off so that the petrol engine is only on for 158 seconds. I guess you have probably seen my video about combining a car wash and recharge ... but just in case this is the link: kzbin.info/www/bejne/eZmQfWOAl8eEi8k I thought I would try and calculate how much fuel a typical car uses when idling ... so I Googled and I found out that the fuel consumption of an idling petrol engine is "0.6 litres / hr per litre of engine displacement" which if my calculations are correct means that 158 seconds for the 1.5 litre engine in my Yaris uses 0.04 litres = 0.009 gallons. So this does seem to confirm my guess that my combined car wash + recharge is using a very small amount of fuel.

[@dinogreattail9234]

I have asked the dealership where I bought my Yaris mark 4 about 5 months ago, what level would the voltmeter have to fall to for the car to fail to start. I can’t get a straight answer to the question. My wife and I do very few miles and since we’ve had the car have done only 230 miles. However, at least once a week I drive the car for 5 miles down the motorway and back again. In addition, I leave the car in ready mode for 1 hour 3-4 days after the motorway trip. I have to say I’m hugely disappointed having told the dealership that I do very few miles and given that an issue with the 12 volt battery has been known about for some time, I feel that transparency was not forthcoming at the time that the vendor was propounding the virtues of this car. Having bought 4 brand new Toyotas in the last 40 years I’m both surprised and disappointed with the company’s research and development, in allowing vehicles to come to the market with this deficiency.

[@Helpful-Stuff]

I agree it can be very difficult to get detailed information about this problem. What I know from experience is: (1) My car failed to start at 9.45V (tested by AA man with a voltmeter connected direct to the battery) (2) The lowest voltage I have seen on my accessory socket voltmeter is 11.2V ... the car started OK So my best guess is that somewhere around 10V to 10.5V is the lowest voltage that will start the car. I think that where a customer, like yourself, made it absolutely clear that they drive very few miles per year then it is morally and possibly legally wrong to sell a Yaris Mark 4 hybrid. Have you considered contacting Trading Standards or Citizens Advice? I had a Yaris Mark 3 hybrid which started reliably for 5 years even during COVID lockdown when I was only using it once per week to go to the supermarket. So I know that Toyota can design a 12V system for a hybrid that copes with low mileage. The Yaris Mark 4's 12V system has a flawed design which means that it can fail to start after a single day without use (based on my own experience). Before my two Yariss I owned a LandCruiser for 13 years and almost 200K miles. So like you I used to be a big Toyota fan - they are not the worlds most exciting or flash cars but they were reliable ....

[@dinogreattail9234]

@@Helpful-Stuff Hi, from what I understand about battery depletion, the greater the number of depletions, the more the battery’s life is shortened. To date, the lowest I’ve seen on my voltmeter is 11.2v. And, of course, what exacerbates the issue problem, is the location of the battery. What I’m not sure of is whether the battery can be charged from the jump-start points under the bonnet. Might this seriously damage the car’s electrics? On the subject of consumer law and threatening some sort of litigation, I just want peace and tranquility in my few remaining years on this Earth.

[@Helpful-Stuff]

How much a battery is degraded each time the car fails to start is another of those detailed questions I would love to know the answer to. - Do Toyota recommend that you get a new battery after the 3rd time a car has failed to start or the 13th time it has failed to start? - After a single failure to start is my battery OK? Its this sort of information that Toyota should be providing to customers instead of just saying "drive your car more". I am certainly not an expert but apparently you canNOT use the under bonnet 12V connections to charge the battery. There is some very useful discussion towards the bottom of page 1 of this 91 page discussion of the 12V battery issue on Toyota Owners Club website: www.toyotaownersclub.com/forums/topic/217673-12v-battery-maintenance-issues-etc/ Look for the comment by (1) DEVON AYGO on 2-Jan-22 and the next few comments which discuss the use of the under bonnet connections (2) CYKER on 3-Jan-22 about an access panel on the base of the rear passenger seat to the 12V battery but from the description it sounds very tight and fiddly and it may be easier to do (3) (3) DEVON AYGO on 3-Jan-22 describes how to unclip the rear seat to access the 12V battery. This is how my AA man accessed the 12V battery when my car would not start. You may want to have a look at a few random pages from this 91 page discussion to reassure yourself that you are not the only person with the 12V battery problem. Its a major issue. I totally understand about peace and tranquillity ... but I just thought I would mention that the legal route is an option for you. Good luck with your 12V battery 👍😀

[@fionasinfield1422]

I have a 70 plate Yaris hybrid, which I initially loved, but I’ve now lost count of the times it has refused to start. I find I have to trickle charge it on a weekly basis. Ludicrous, for such an expensive and supposedly hi tech vehicle! I’ve been back to the dealers, they just laughed and told me I don’t drive it enough. I’m retired and I don’t need to drive much these days. 20-30 miles a week is my usual nowadays. Been driving 40 years and never had such an unreliable car, I don’t recommend it to anyone who asks, and will never buy another. Toyota risk serious reputational damage by refusing to resolve this issue.

[@Helpful-Stuff]

I agree with everything you say. I do a lot more miles than you but my car failed to start when only 10 months old and after just one day parked. So while this problem does affect low mileage owners more often ... the problem affects average mileage drivers like me .... and I have also had comments from high mileage drivers who have suffered from a failure to start. The problem is the Mutlu battery. I think your battery is seriously degraded after so many failures to start. I think each failure to start slightly degrades the battery and this makes it more likely that the battery will fail to start the car again. It sounds like you have had a LOT of failures to start so you battery is seriously damaged. You need to get a new battery. I think that you should get a Yuasa battery fitted instead of the Mutlu battery that a Toyota dealer will fit. I haven't tried the Yuasa battery yet but I have read many comments from people who have had a good experience with this battery. I also think that you should get an AA Solar Trickle Charger. This was recommended by my dealer. Somebody left a comment under one of my videos a few days ago to say that they have been using a solar charger for several years and they have not suffered another failure to start - so it does work. kzbin.info/www/bejne/mYTJmp5qrt6LnNE I only use this if my car is not going to be used for 24hours or more and I think you should do the same. Toyota GB issued a Bulletin to all dealers I think somewhere around April 24 that listed cars where dealers should change the 12V battery under warranty with no need to test the 12V battery in the car. You should ask your dealer to check if your car is on the list of cars in this Bulletin. If your car is listed you will get a new Mutlu battery. However, with a new battery you will still need a solar trickle charger to keep the battery topped up because you do low mileage.

[@fionasinfield1422]

Thank you, I’ll look into this.

[@fionasinfield1422]

@@Helpful-Stuff just want to thank you again, my car is going in for battery inspection on Tuesday and hopefully they’ll replace it under warranty. I’m having to trickle charge it weekly, it’s ridiculous!

[@Helpful-Stuff]

@@fionasinfield1422 Can you post a comment to let me and everybody else know what happens as a result of the battery inspection? Hopefully you will have a good outcome and the information will be useful to other people who are suffering from the Yaris 12V battery problem.

[@fionasinfield1422]

@@Helpful-Stuffwill do 👍🏼

[@CarlSmith-bs4qx]

These are not cheap cars to purchase new, Toyota just need to fit a battery up to the job, this problem put me off purchasing one as a second car.

[@Helpful-Stuff]

Totally agree. My Yaris Mark 3 started reliably between 2018 and 2022 - even during COVID lockdowns when it was only used once per week. I was angry and disappointed when my Yaris Mark 4 Excel with Tech pack which, as you say, cost a lot of money failed to start when it was only 10 months old with 6,000miles on the clock and after only ONE day without use!!! I have read that the Yuasa battery is a much better battery than the Mutlu battery that Toyota use. If my car fails to start again I will go to a local garage and ask them to fit a Yuasa battery.

[@bbc1255]

A fully charged 12volt battery should show 13.4 volts, a discharged battery would show a reading of 11.4 volts.

[@Helpful-Stuff]

You are quoting voltages measured at the battery terminals when there is no current being drawn from the battery. That is not what I am measuring with a voltmeter plugged into the accessory socket. There is a lot of wire between the battery under the rear seat and the accessory socket so the voltage will not be the same at the battery and at the accessory socket. The voltage measured at the accessory socket will always be lower than the voltage measured at the battery. The car is in accessory mode so some of the car's 12V systems & computers are switched on ... the most obvious being the screen and multimedia system. These draw current from the 12V battery and will reduce the voltage. Toyota changed my 12V battery a couple of months ago so I now have a brand new 12V battery. I have obviously kept my voltmeter plugged into the accessory socket and I am seeing voltages about 0.5V higher than shown in this video. Most of the time I am seeing 12.3V in accessory mode ... occasionally it is as high as 12.5V and occasionally as low as 12.1V and this has been consistent over the last 2 months since the battery was new. The fact that a brand new 12V battery has never shown a voltage higher than 12.5V when measured at the accessory socket confirms that voltages measured at the accessory will always be lower than the voltage measured at the battery terminals with nothing connected to the battery.