Explaining why the 12V battery in all hybrids and EVs depletes - and how to manage the problem!

[@DnDwiJam]

I've lost hours trawling the internet for this explanation! Thanks, very clear and extremely helpful!

[@herbertcollier5170]

Hi Steve. I am on my 2nd Toyota hybrid (Auris). I use my car almost every day, so I never encountered the dead battery issue you mention. I did get caught out however, with my current Auris purely because the 12v battery was getting past it's best. One day, I got in the car and got a warning on the dash 12V battery low. I ignored it as it booted up as normal. A week or so later, same warning message, I (stupidly) ignored it again. You guessed it, 3rd time of the same message I was unlucky, it failed to boot. I didn't have a portable battery pack, but I am in the AA. They concluded the battery was indeed in need of replacement. They managed to get a hybrid compatible one for me via their system and fit it for me within a couple of hours. (Bosch stop start type) Bear in mind the failed battery was original to the car and 8 years old, so it was probably on borrowed time. The Bosch battery had a different vent tube fitting, so I had to fiddle with various tube adaptors etc obtained via ebay. You are wise to carry the portable jump start unit. Even with a bad battery, this will boot the car and get it running until you can sort things out. One point to mention, when your key fob battery starts to get low, a warning pops up on the screen to tell you. Enjoy your car. I love my Toyota hybrid, never broke down until the car warned me, I will not ignore the warning next time!. Regards Herby Collier

[@TomWalsh0]

I had a similar situation when I left my Auris at the airport for a week. Luckily, I'd invested in a jump pack but the battery wouldn't hold charge overnight so I replaced it. In fairness it was 10 years old and I knew I was on borrowed time. No warnings before that so I think being off for a week must have pushed it over the edge.

[@datathunderstorm]

The 12v battery in my 2008 Prius is literally 10 years old and still functioning normally. I should start to worry - especially with winter creeping forth 😮.

[@Fred-ui6zk]

I do understand the issue (and had some experience with my Lexus LBX....) but think this can be avoided by different measures. A simple one is having the hybrid battery automatically charge the 12V battery if needed. The hybrid battery is way larger and should be able to do this (if it has sufficient load of course, not if it is "flat"). This is a manufacture thing, not only physics...

[@markstephenson4960]

Thank you for a very clear and illuminating video. The12v in my Nissan Hybrid has died, and your explanation has helped me understand then issue better.

[@johnmilller7218]

When I kicked off with my Toyota dealer, having had the AA out twice to start my Yaris Cross. They gave me a 27watt solar power panel which has solved my issue. Thanks RRG

[@SM-kp6px]

Can you please confirm how this helped? Do you keep it linked to the battery somehow to provide a trickle charge?

[@coachhouse34]

I thinking of buying a Yaris cross, but this problem with the 12v battery is putting me off getting one. It would seem reasonable to expect a modern car to restart after being parked up for say a month. If the electronics are drawing too much in standby then the 12v battery needs to be bigger

[@stevelitchfield]

I wouldn't disagree - they should factor in larger 12V batteries.

[@veronicathecow]

Steve litchfield, I know that name. I was a huge fan of psions. (especially the 3c) and I recall you were of help with something to do with them, so thanks your are not forgotten.

[@MobilAvenue_]

Yesterday was the first time I’ve used my EV since the 18th of August. It checks the voltage of the 12v now and then and if needed uses the 60kw traction battery to keep it topped up. I’d only lost 2% battery charge percentage. Left it at 60% came back to 58%.

[@TheSmallRabbit]

That's a smart EV. Which model is it by the way?

[@MobilAvenue_]

@@TheSmallRabbit Renault Megane Etech

[@MobilAvenue_]

@@TheSmallRabbit Renault Megane Etech

[@morganmuffel2678]

I have a elderly relative who might only use her Toyota hybrid once or twice a week for short trips to the shop and I'd regularly have to call around because the battery was flat. I had Toyota check it and they said it needed to be driven more than she uses it. She had Toyota's for decades which never gave her this kind of problem so she traded it in for a non hybrid car. I wouldn't touch one simply because you shouldn't have to worry about whether your car will still start if left in an airport carpark for a few weeks.

[@shubinternet]

You have the same problem with any modern pure gasoline powered Toyota or Lexus vehicle. If the car hasn’t been run for a week or two, the 12V battery will be flat.

[@adienowed6366]

Useless bloody cars then and obviously best avoided at all costs!

[@freezado8573]

​@@shubinternet Not true. Toyota Aygo X for instance has a 60Ah battery while the more expensive Yaris Hybrid has a 30Ah one. Aygo X has no systematic battery issues reported.

[@loulouzia]

That’s exactly my situation. I wish the Toyota salesman had told me about this serious downfall of hybrid cars and told me a fuel car would be best for me. Now, I’ve got the hybrid, and I’m finding out the hard way, it wouldn’t start on Xmas day! It had been driven 4 days prior, that’s not a long period at all.

[@5kram]

I have a 2018 Nissan leaf occasionally I see the blue lights on the dash flash when the car is off and locked this is when the traction battery is topping up the 12 volt. So no worries on the 12 volt battery on the leaf.

[@GordonHudson]

Nissan got around this problem with the Leaf by fitting a proximity sensor to the on off switch. If the car fails to start because the 12v battery is flat, you push the start button in with the end of the remote key fob. This is detected by the car and it converts a small amount of current from the traction battery down to 12v. Just enough to boot up the computer. This gets the car moving with basic display functions but no heating, aircon or lights (not until the 12v has had a chance to fill up again). The problem Kia and Hyundai had was that their software was only charging the 12v if the regeneration got above a certain level. When they updated the software it fixed the flat battery problems they were having. My wife's petrol Qashqai has the same battery draining issues. A lot of it is down to AGM batteries and short journeys. The alternator won't put enough current in to keep them charged. After a week undriven it needs jump started.

[@garygarski]

I've owned a 2007 Toyota Prius for 12 years. During that time, I would do a long-term shutdown recommended by Toyota. They said that after you do that, the car would completely shut down. I never disconnected the 12-volt battery and followed the Toyota recommendations. After 8 years the 12-volt battery did not make it through my 4-month traveling holiday. I then called the Toyota dealer and they send a person to jump the car and the Toyota techs changed the battery. Everything was fine after that.

[@roberthuntley1090]

I monitor mine (Lexus UX) using a digital volt meter that plugs into the cigarette lighter socket; cost about £3 from Amazon so not expensive. I had to have the car jump started in 2020 since I wasn't doing enough miles during Covid lockdown, so bought it then to keep an eye on things. When the hybrid system is powered up, it basically applied three voltages to the system (I do some brief transitional voltages, but they don't last long): 14.4 volts means that the battery is being actively charged. 12.4 volts means that the battery has reached full charge and is being floated (I only see this in Drive or Reverse). 13.6 volts when a fully charged battery is put into Park (sometimes this goes to 14.4 initially, and then drops to 13.6 later). I think this is a slight overcharge to top up the weaker cells of the battery and so balance it. As a result, I've taken to using Park more often at traffic lights etc. instead of using the auto-hold function. The scary number is how low the voltage drops for a fraction of a second when first starting up the hybrid system. This week it was down at 9.8 volts after the car had been parked for a week, so I took that as a prompt to use a trickle charger overnight after that journey.

[@gilbrook]

Considering purchase of 2025 Kia HEV. This car has a 12V battery recharge button on dash w/1kW Lithium-Ion. Any guesses on how likely car would start using the recharge button after being left unattended for 3 months?

[@evitoonbundit2453]

My 2009 350.000 km Prius still enjoys its original 12v battery. Guess often use helps.

[@Magpieboy1]

Very enlightening video this. I've had my 2022 Toyota Yaris Cross hybrid now for about two months now and today was the 4th time in a month that I have had the hybrid malfunction warning come up, with numerous other faults coming up as well (LTA and collision detection were two that failed, but after turning the car off they reset themselves), I also had the check engine light come up, and saying to visit my dealer, a bit hard when it's a Sunday. The first time they said the battery was flat and they recharged it and said that to make sure we drive it a reasonable distance once a week (It only takes me 6 mins to drive to work one way). We did that for about a month and then it happened again, twice in two days (the car will reset itself sometimes), this time they asked us if we were making sure the car was locked each time we had the car parked, which we did. It would only be unlocked for short periods of time. Their diagnosis was that the car was trying to constantly communicate with the fobs, due to it's close proximity. So we decided to put them both in a tin (basically a Faraday box, I tested it and the car wouldn't open even if it was right next to it), and the furthest place away from it in the house. We started doing that on Christmas Eve and today it has done it again. So what's my next step (aside from yelling at my dealer to fix the problem, especially seeing its still under new car warranty), start disabling all the safety features, and anything that the car will use to connect to outside devices. We love the car, but this is frustrating.

[@stevelitchfield]

The obvious thing is to get them to change/upgrade the 12V battery. If that doesn’t work then there’s an electrics fault. But battery change is simple and easy, so try that first.

[@garethwilliams2173]

I’ve had that problem with my hybrid Corolla from new. I’ve installed a Bluetooth battery monitor and I think part of the problem is that the car doesn’t fully charge the 12v battery. It’s much healthier when it’s been on a trickle charge. Didn’t get anywhere with my Toyota dealer though.

[@TheRoybeasley]

Interesting - but not quite true as regards *all* EVs. My Tesla Model 3 has a 12V battery, but even when the car is "switched off" (Tesla call it "asleep"), the 12V battery is monitored from time to time and, if it depletes a bit when parked up for a long period the car will "wake up" enough to close those contactors and put a little charge into the 12V battery before going to sleep again. The weakness in this case of course is if the 12V battery has deteriorated internally (not just run down a bit) the very act of trying to close those contactors might pull the voltage down too far, leaving the car unable to top up its own 12V battery. Then it will indeed need a jump start (and a new 12V battery). Somewhat cleverly, if the onboard systems detect a failing (or failed) 12V battery, they have the capability to run everything off the traction batteries, meaning that the car doesn't actually "sleep" (and discharges its traction battery rather more quickly as a result). All ths clever stuff stops working if the traction battery reaches a low state of charge, protecting it from being fully discharged and thus damaging it. Bottom line is to be aware of any 12V battery warnings your car might give you, and consider replacing the 12V every few years to pre-empt the possibility of failure. My Tesla is 4 years old and was on the original 12V battery so I simply replaced it anyway - only cost £90 as it's a bog standard flooded cell job.

[@Enjay001]

This is precisely what I assumed EV and hybrid vehicles would do. I knew that they charged the 12V battery when the car was on. I foolishly assumed there would be some low-level monitoring of the 12V battery when the car was off too. If it gets too low, flip a few relays and pump some charge into the 12V battery. Surely, that has to be better than having cars unable to start when the owner is away for a couple of weeks, or hasn't driven the car for some other reason (of which there are many possibilities). Apparently, most manufacturers don't agree.

[@markharris8929]

@@TheRoybeasley thanks. I’m just about to take delivery of a 3 1/2 year old Model 3. I will check which battery it is as it dates from around the changeover. I think it’s a 12v as it’s an Intel Atom rather than a Ryzen processor I noted but I forgot to see the battery type.

[@TheRoybeasley]

@@markharris8929 I believe the change to 16V was in 2022 (about the same time as the change from Intel Atom to AMD Ryzen).

[@markharris8929]

@ thanks. Mine will be 12v then.

[@garykendall3776]

Way in the dark ages of 2008, the Prius handbook advised that the 12 v battery should be disconnected if not to be used for 2 weeks or more. This I did when going away for a month or so. No trouble restarting. I have followed that advice since then on all my hybrids even if the "book" didn't mention it. If you have a Toyota computer that "adjusts" to your driving style, it will revert to factory settings when deprived of 12 v power for that time.

[@stevelitchfield]

Not that easy to disconnect on some modern designs. On my YC, the 12V battery is under the rear seat!! 8-) But a good point made if users have access!

[@brianbest3777]

Surely this knocks off the alarm system?

[@azlansharom7011]

Granted there is a wide variety of behaviours by manufacturer. My BYD seems to constantly charge the 12V when the car is ‘off’.

[@Helpful-Stuff]

This video is TOTALLY INCORRECT when it discusses a Yaris failing to start after a couple of weeks parked ... my Yaris failed to start after ONE day parked!!! I am an experienced Hybrid owner and I was a Toyota fan ... I owned a LandCruiser then a Yaris Mark 3 Hybrid 2018 to 2022 which started reliably even during COVID lockdowns when it was only used once per week to go to the supermarket. I bought a Yaris Mark 4 Hybrid in 2022. When this car was 10 months old with 6,000miles on the clock it was parked and not used for ONE day and then would not start. The AA man said he sees a lot of Yaris Mark 4s which will not start. He accompanied me to the dealer and told them that the voltage was so low that the battery needs to be changed. The dealer recharged the battery overnight and told me that the battery was healthy and I need to drive the car more. They also recommended a solar trickle charger. I had done 6,000miles in 10 months so I drive around UK average mileage and the car only has one or two days parked per month. If I do not drive my Yaris enough then a Yaris should only be sold to high mileage drivers who drive every day. I fully understand the generic issue with hybrids and EVs that you explain in the video but the problems with the Yaris 12V battery are not explained by these generic issues. The 12V problem is explained by Toyota fitting a low quality 12V battery with insufficient capacity 35Ah. Halfords will fit a Yuasa 45Ah battery that will apparently solve the problem. I will be going to Halfords if my car fails to start again. The problem is exacerbated by Toyota GB blaming the problem on their customers not driving their cars enough when it is Toyota's choice of battery that is problem.

[@stevelitchfield]

I completely agree that the car needs a larger and better battery. Your issue was certainly that the original, poor battery wasn’t holding a charge properly. Thanks for the Halfords tip!

[@GlennLaycock]

Hyundai / Kia - I assume others, have a "head scratching button" that solves exactly this situation when you try to start them and the 12v is discharged. Not sure the in and outs but you push it and it will revive the 12v.

[@loulouzia]

Thank you for this enlightening video. I got a brand new 2024 Toyota Corolla Cross XSE Hybrid at the end of June. I was not aware of any of these issues with the 12V battery and I was in for a very nasty surprise right on Christmas day. I loaded up the car with presents and food, along with my daughter and her three kids to go and celebrate with my dad, but the car wouldn't start! We resorted to a Plan B. The next day, a good samaritan boosted my car up and I drove it almost an hour to make sure the battery was fully charged. The following day, I called my Toyota dealer to get a nonchalant advisor tell me "oh that's normal, you have to drive your car every day for an hour and a half". What? No way! The car had been on the street for only 4 days, surely that's not very long. The temperature was a bit low, but not frigid. -10 to -8 degrees Celcius, thus 14 to 18 degrees Farhenheit. I'm thinking of selling it and getting a gas only car. But truly, I'd rather keep my car, but I can't drive it daily. Weekly maybe. I'm retired and I can easily go 10 days without driving it. I heard your suggestion about the portable booster. What if it too is discharged? Any help/comments will be greatly appreciated. Thanks, Andrée from Montréal, Qc Canada.

[@stevelitchfield]

A portable power pack will hold a charge for many months.

[@loulouzia]

a) what would be your recommendation for how often and how long I should drive it? b) I read that it’s not good to keep battery chargers in too hot or too cold weather. But to have to keep it in the house in winter seems to defeat its purpose. c) thank you. Andrée, Montréal, Qc Canada.

[@andreedeveault5556]

I’m all set. I’ve got a portable booster which I’ve charged. I understand where to put the red clamp. It’s the black clamp that has me hesitant. Because apparently it mustn’t be too close to the red one, yet, the cable won’t reach very far. Thank you.

[@manjitsaimbi3730]

I have recently bought a KIA Niro. It actually has a button, by the steering wheel, which can be pressed to refresh the batter from the larger Hybrid battery. Good thinking.

[@stevelitchfield]

Well yes, but the main Power button does the same thing, in effect, in the Toyota. You just get lights and other auto-stuff as well!

[@sim6699]

Consider a bluetooth battery monitor for the 12v battery.

[@jimb7406]

Good idea. I fitted one to my Rav4 hybrid. I also fitted a Ctek plug and cable to the battery and can now easily charge the battery by passing an extension lead into the boot and hooking up to the Ctek charger plug. The rear tailgate closes and latches without damage to the cable. If you keep a jump pack in the car don't leave it in the boot if you have an electric release. Leave it under a seat or in the centre console storage. I typically boost the 12v battery every 2 weeks in the winter when I am using the heated seats, heated steering wheel and operating the electric tailgate several times a day to let my dogs in/out. I only do short local journeys so the battery doesn't get enough time to recharge fully in winter.

[@edc1569]

My golf GTE is on its original 12V battery, never run flat, it’s 7 years old now. I’ve left it for 5 weeks before.

[@robinbeckford]

So the 12v. battery doesn't have the capacity to start the ICE? Did I hear that correctly?

[@TheRoybeasley]

Yes - the Toyota hybrid system uses traction battery to start the petrol engine. The 12V battery just runs the computers and all the "regular car" stuff (lights, wipers, radio, blowers, heated seats etc) and when starting the ICE only needs to provide enough current to close the contactors to switch-in the traction battery which then does the heavy lifting of actually cranking the ICE.

[@robinbeckford]

@@TheRoybeasley Thanks. That makes sense.

[@user-xu5vl5th9n]

@@TheRoybeasley Not sure this makes sense. There are hugely reduced demands on the 12V but now there are more issues.

[@maurice7413]

@@user-xu5vl5th9n one of those issues is learning not to use the 12v battery the same way as on an ICE car. I finished off my 2017 Ionic EV 12v battery by using it to power an air compressor while the car was off. I used to do it all the time with the ICE vehicle because it only took about 4 minutes. The thing is I bought the Ionic in 2020 and the battery was 4 years old. I now use a battery station to power my compressor. Also avoid using it in accessory mode too long.

[@stevelitchfield]

Or power an accessory with the car turned 'on', so that the big hybrid battery is included as well.

[@Smile342]

Hell9 are you happy with the Audio System??Would like upgrade to a better system??Have been told by the dealer that they cannot upgrade to the jbl system

[@stevelitchfield]

It’s good enough. And I’m usually quite fussy. It’s not as hifi as my Old Ford’s, ditto the JBL models. But it’s fine, it surpassed my expectations at the price etc.

[@polo99a9]

Sounds like s problem that should not exist on a car with a 1kw hybrid battery.

[@MrAdopado]

kWh presumably ...

[@polo99a9]

@@MrAdopado you are correct.. kWh

[@Stiggy767]

It effects cars with 50kWh batteries!

[@Robotadept]

Had this on my MG PHEV came back of holiday car completely dead got MG assist out who jump started it but dealer had to change the 12v battery which isn’t included in MGs 7 year warranty cost ME £225 🤬

[@KiwiMechEng]

The Hyundai Kona Electric for example does most of the 45Ah auxiliary battery charging while the car is parked, not while driving. That is 14.6V for 20 minutes every 4 hours, more than enough to keep it in top condition despite perhaps a 25mA continuous draw. After 60 hours parked (or if the traction battery drops under 40% charge) that changes into a lower-power program which only wakes the car up once a day to carry out a 12V charge, still adequate. While driving the charging is much like an ICE car, dithering system voltage between 13.1 and 14.7V. The only issue here is that owners are not made aware in the owner's manual that the auxiliary battery has to support the entire car after any door is opened, until the car is placed in Ready (driving) mode, or the "Utility" mode specifically intended for stationary use of 12V systems. After the car is turned off it takes 9 minutes for it to reduce the 12V load down to the normal quiescent level. As a result the aux battery is always left slightly discharged after arrival. I've never had a problem myself (six years so far) because I'm aware of this trap. Tesla changed to an LFE auxiliary battery a few years back simply so that its dedicated BMS can alert the car (over LIN) that traction battery support is required. It does this frequently as the LFE has only a small capacity.

[@arne-erikornum1861]

Excellent description !

[@negofol5278]

Most manufacturers request that you use a battery conditioner (e.g. Ctek) if the car is parked for more than 2 weeks, due to phantom loads. This is also true for modern IC cars. Ferrari for example ahve a dedicated connection in the trunk.

[@SM-kp6px]

This is a really good interesting video which is now made me understand the problem I’ve just encountered. I left my car and regularly leave my car at an airport for sometimes 3 to 4 weeks. I recently returned to find my car battery was drained. Is it possible for me to get a quality normal 12 V battery that is used on a normal car i.e. not a hybrid?

[@stevelitchfield]

Not really, the sizes are different. Best just keep an emergency charger pack in the glovebox etc. It’s what I do!

[@arselihp]

If the battery is the one that came with the car, there may be a better option available. For the latest Yaris and Yaris Cross, many people have swapped the original 35 Ah battery for a Yuasa 45 Ah battery (same physical shape/size) with good results.

[@keithlynwood6417]

Hi, you mention a week between driving. My Yaris Cross 12V Battery has failed seven times in 2 years. I take it on a 10km circuit incl motorway driving and slopes to charge hybrid battery every two days because after three days battery is flat. Yesterday after 42 hours since last trip voltage abnormality steering power low braking power low no ready light . Had to call breakdown guy again.......Frustrated to say the least........It cannot be relied upon. I need to buy a decent battery. any suggestions?

[@stevelitchfield]

That sounds wrong - even with Toyota's gadgets draining power, it should still take a week or two to drain the 12V battery. I'd get it changed at a dealer, where they'll know the size needed. Hopefully they'll do it for free if you complain and produce evidence.

[@keithlynwood6417]

@@stevelitchfield It did it again yesterday after two days. Another call out and to Toyota dealer where they did the usual check on the MUTLU Turkish 12v. Said it was absolutely fine (of course). This time I said I would pay for a stronger 12v and had a YUASA Japanese 12v fitted at my cost naturally. I don´t mind taking it out every couple of days but if it happens again. I will part ex it for a new gasoline only car.

[@CageyLeigh]

Does the hybrid battery always charge the 12v battery when the car is on, or only when the gas engine is running?

[@stevelitchfield]

Anytime the car is powered on.

[@peteg8920]

It would be interesting hearing your thoughts regarding the longevity of high voltage battery. As pensioners , my wife and I chose the new Yaris after being predominantly persuaded by the ablity to run shorter distances on electric power and to only use the car two or three times a week. However, there are opinions out there that say the car should be used more regularly in order to maintain the effective life span of the high voltage battery , which to me seems to defeat the object of owning an lesser polluting car.

[@stevelitchfield]

No, you're fine. Twice a week is ample to keep the 12V battery from discharging too much and to also give the hybrid battery some exercise. The life span of the latter is not relevant here. The hybrid battery will last the life of the car IMHO.

[@janmessek1826]

funny thing is people usually plug it in and leave it in a garage and the 12 volt battery can still run down when the AC power plug is about a foot away from the 12 volt battery in the rear quarter trunk as in the plugin Prius 2015 model. A small trickle charger could solve the problem.

[@tonykelpie]

I think in theory appropriate control systems and a transformer should be the answer to this problem. It looks like Teslas have addressed this already

[@DerekHasted]

Transformers don't work on direct current - maybe you mean a DC-DC converter?

[@tonykelpie]

@@DerekHasted yes. Thank you

[@G6EJD]

Some facts are wrong, a typical vehicle is designed to consume ~100uA from a 12v battery. This is done so that the vehicle can be left at say an airport for many weeks. What discharges a 12v battery is when the auxiliary circuits are left on, especially when the vehicle is waiting to be charged from 230v and not being allowed to enter its sleep mode.

[@MalinDixon]

100 μA is a very low value. Some manufacturers allow up to 100 μA for any one electronic module in sleep mode, many of which are powered the whole time. I have seen quiescent current consumption a being 10 - 20 mA for a modern car. On a 60 Ah battery, 20 mA would be several months to discharge.

[@G6EJD]

The JLR specification for the whole vehicle is 94uA

[@ML-qk1px]

The 12V battery in my 2022 RAV4 died a few months ago. It was covered under the 2 year warranty but I did need the AA to get me started and follow me to the dealership and they “investigated” the issue and concluded it was the 12V battery and replaced it. No apology. I can’t even remember the last time I had to replace a 12V battery in a car, so I’m hoping this was a blip.

[@stevelitchfield]

Indeed. 12V batteries normally last six or more years. Mind you, they're cheap to replace. Also, haven't you got the full 10 year warranty?

[@ML-qk1px]

@@stevelitchfield I do have the 10 year warranty active as long as I keep going to the Toyota dealer for servicing, however the 12V battery only has 2 years warranty. I was lucky to get it replaced as I wasn’t far off that limit. I would have argued that it should last longer and hopefully with goodwill they would relent.

[@alsjogren7890]

A 7 month trip to Mexico leaving the Nissan Leaf in Seattle. My plan is continuously trickle charge the 12v battery, keep the traction battery plugged in, and ask my daughter to unplug and plug in the traction battery every 2 months. Does this sound like a good plan?

[@stevelitchfield]

Not sure what you mean by 'unplug' etc - but just turning the car on for 10 mins a fortnight should do, with that trickle charge as well. Best be sure.

[@peterscott2662]

This happened to my Miata (not a hybrid/EV) in winter. I only drive it when the roads are totally clear, and the battery gets lower and lower over time. So I just started trickle charging it in place. Problem solved. My elderly Mom seldom drives, same problem with her regular ICE car, and same solution, I trickle charge it occasionally. Can you put a trickle charger on a hybrid/EV 12V battery? If so, that seems like a reasonable solution to me. Rather than have neighbors turning on your car.

[@stevelitchfield]

Yes, trickle chargers will work, though you'd have to run the wiring in under the fuse box panel in the Toyota's case.

[@chenyansong]

My Nissan leaf’s 12V battery died once because I forgot to turn off emergency light after a minor accident, although it has plenty of electricity left in its 24kwh battery. It refused to start and I have to get a gas car 😂 to jump start it.

[@WilliamLaverick-wo1nb]

My friends Mazda 2 hybrid would not Start because the so call secondary battery went flat. It’s only two years old.

[@norwichnorfolk1584]

Have now got a solar panel, got it from Toyota! Interesting they sell them…

[@TheSmallRabbit]

I have a BMW i3 which has a small 12v too, however when you open the boot, doors and its low the car switches the 12v charger on. However if I was leaving the car longer than 3 weeks I would just plug it in and leave it plugged in until I got home. Another thing is to replace it sooner rather than later. I put a new on in at 4 years old just to be on the safe side. As you say if you switch the car on within a reasonable time which for me is within 3 weeks I am sure it would go much longer it will be just fine. Why on earth there is no automatic charging when the 12v gets critically low amazes me when its sat on top of the largest battery in the world :-)

[@pravardhanus]

During Covid-19 lockdown, Maruti Suzuki had asked the customers of mild hybrid to start the engine with headlights in ON condition so that the lithium ion battery will also get charged.

[@Mr.Professor-f4v]

Good advice.

[@julesviolin]

⚠️This 12v drain has been around for 25 years or so since the introduction of car alarms and remote central locking gadgets. Buy yourself a booster pack They are pocket size these days. When not in use, I keep my 2003 Rover 75 charged with a solar panel on the dash plugged into the OBD port which has a permanent 12v connection. OBD sockets on most cars have live pins. Get yourselves a solar panel rated at 6 - 12Watts minimum to provide 500mA - 1A or better. Most drains on cars are typically 50 - 100mA so you need at least double that current to maintain the battery above 12.5V. In winter, the solar panel won't even output 1/3 of it's rated output which is why you need a panel half the area of the dash but well worth it for car always to have a battery resdy to go ⚠️

[@stevelitchfield]

Indeed. Good info. Though if the car is used every day then drain isn't an issue, of course. (I use my YC at least twice a day and top 12,000 miles a year.)

[@stribs44]

It also is a problem with the COROLLA, my partner managed to flatten the 12v battery on a visit to visit a family member at a care home just by sitting in the car with the radio and one seat heater on for a short time whilst waiting to go in the home.

[@stevelitchfield]

That's not the same! Your example could have happened at any point in the last 100 years! 8-)

[@paolopetrozzi2213]

Hi, thanks.

[@funlovingJohn]

Might be somewhat true for a regular gas engine car as well.

[@sspoonless]

Good reason for updating the industry to 48v utilities. Highlights a need for smarter software to automatically power up the car periodically to charge the utility battery. People should not be required to manage this manually.

[@Skoobedobedo]

If you didn't have a neighbour to power up the car once a week and you were away for say a month, would one of those small solar panel battery chargers hooked up to the 12 volt battery keep the battery charged?

[@stevelitchfield]

Yes, sort out the wires and you're good. An idea for a followup video?! 8-)

[@lewisjohnston6831]

Ok i get that so is it better to put in a better battery with higher amps i,e Yousa 5000

[@stevelitchfield]

The more the better, but I’d ask Toyota dealership for advice. I assume that if you paid for the upgrade etc…?

[@ourv9603]

ALL 12v batteries in all kinds of cars deplete because the vehicle computer is still on & awake consuming power. Park your car at the airport for a couple of weeks and you will come home to a dead battery. !

[@rockinginafreeworld3256]

You cannot leave a a key with someone if you take your car to the airport.

[@stevelitchfield]

Indeed. Or run a solar trickle charger if you're in a multi-storey!!

[@HJPorschen]

'...leave the keyfob with a friend or neighbour...' A friend did that some years ago so that he could check the car occasionally while she was away. But, without permission, he drove the car occasionally. And then he had an accident; nothing major, but some damage. Because the neighbour was not a named driver on the insurance policy, the insurance refused to pay for the damage. But that was not all. She was also fined by the court for giving the key of the car to an uninsured driver, and so enabling and indirectly allowing him to it! So, be careful what you are doing and recommending!

[@stevelitchfield]

Heh. And be careful with neighbours you don't trust!! 8-)

[@Spiritualwarfare587]

Bmw charge 12v battery with high voltage battery.+. It have 2 12v batteries 1for starting engine 1for all electronics

[@DusanDmitrovic-f8i]

Endemic means that something is found/happening in a limited area. Therefore the word you could use is ubiquitous. 🎉

[@stevelitchfield]

I meant as in 'pertaining to this class of technology'. 'Ubiquitous' would imply it happens everywhere in all tech and that everyone already knows about it.

[@DAVIDSHARPLES-u5o]

For this application surly a leisure battery as in caravans would be better than a car battery

[@stevelitchfield]

Yes, they could put in a much larger 12V battery - I guess it's a weight and cost thing...

[@trevorhartley5166]

Wish I had known about this problem with the Toyota yaris 2022 I would have not got it for my wife. Twice at airport parking and once I sat in it listening to radio for 1.20 min waiting to pick up and because I did not have ignition on the 12v went flat I bought a 12v booster pack but there is no way my wife could fit this likes the car but hates the uncertainty

[@markharris8929]

Every canny owner knows a Nissan Leaf kills its 12v in four years. It’s the 12v that gives you the reference voltage for measuring your drive battery. So if your range starts to drop, you windows slow down going up or down or any other problems like not starting ( 12v allows the ABS pump to keep pressure). Any of these and a four year old means a new 12v 45Ah. £50 from Nissan.

[@stevelitchfield]

To be fair, even in traditional petrol cars, it's recommended to change your 12V battery every 6 years...

[@markharris8929]

@ true. But your battery doesn’t show your fuel tank under-reading.

[@anthonyschofield7807]

My Honda E has many times refused entry via the remote after only a couple of days of not being used and required the emergency key to open the door which is a bit hit and miss. I found that my dashcam which is powered from the Obd port was causing a significant drain on the 45 ah battery so I now unplug it when not driving

[@billmacrae1924]

I don't understand why you even need a 12v battery. There is a big traction battery that can be tapped to provide all the 12v power needed for accessories.

[@christopherpeters4815]

It would be fine if Toyota told you about this issue before you buy one. As they don’t tell you this it seems like the product is not really fit for purpose and one may argue that one may be able to have a legal claim against Toyota.

[@scottvessey915]

In other words, exactly the same as when you don’t drive an ICE vehicle 🙄

[@datathunderstorm]

Yup! I had surgery recently and couldn’t drive my Prius (with a 10 year old 12v battery) for 5 weeks. Every week, I went and ran the engine while the vehicle was static. Not satisfied, I got a neighbour to drive me around the block a few times one day, and then finally talked my wife into driving the Prius - which she did rather exceptionally well for about 40 minutes. The 12v still hasn’t gone flat. Yet!

[@GabrielVoinea]

For EV's the information is completely inaccurate. Any EV is permanently monitoring the 12V battery and, if the voltage drops below a threshold, it starts the DC to DC converter that charges it from the main traction battery. That's why, if you leave the car for a week unmoved in the winter, you'll find the traction battery's SOC lower by a few percentage points, but the 12V battery will not be depleted.

[@madm4tty]

Try telling that to a Kia/Hyundai EV owner, they were notorious for not adequately charging their 12v batteries..

[@bikeman123]

Not true. It is well known that Teslas only charge the 12v battery when their hi voltage battery is below 80%. If parked up above 80% the 12v battery depletes. No all evs are the same.

[@petehaidinyak9084]

My 2024 Prius Prime has had a dead battery 3 times since I got it. Usually after I leave the charger cable plugged in after it has finished charging. They ended up replacing the battery and I added a Blu-tooth start of charge unit to the battery to make sure I know it’s voltage level. Toyota is aware of this problem.

[@colinbrammeld2038]

That doesn’t work either in VW id3. Left for a week and low battery warning light is on the dashboard.

[@stevevoller]

Skoda Enyaq require the car to be on for 12v to charge from main battery.

[@EandS65]

I was looking at purchasing a Toyota Yaris 72 plate and was wondering about the battery usage. Although I will be using the car daily for short commutes to work around 20 minutes each way and only local driving, reading these comments are really putting me off. I’m a single lady and don’t need the hassle.

[@stevelitchfield]

20 minutes each way every day is more than enough to fully recharge the 12V battery every time.

[@richardh1467]

👍👍👍

[@stuartburns8657]

Do you realise how insane all that sounds?

[@pauls3075]

I think the easiest way to solve this problem is not to buy an EV.

[@pepeshopping]

Wrong. Smaller batteries do not deplete faster when inactive. Much less when such battery is AGM! It's a design or compromise issue. The 12 volt battery should get RECHARGED by the high voltage battery when sitting for a while. Period! The REAL reason is probably the Telematics, but again, that IS a DESIGN ISSUE!

[@nanookmoose]

Bonnet.

[@victorgrasscourt3382]

Why bother with hybrids? All those potential problems and costs

[@bikeman123]

Arent car manufacturers aware that they could downstep the hybrid battery to run all the 12v systems and so away with the 12v battery.

[@stevelitchfield]

In theory yes. But there are safety concerns in having the big high voltage battery 'on' all the time, I think.

[@EvzenEmanuel]

This video unfortunately does not explain why hybrids and EVs in particular has issue with 12V batteries. This video basically says the 12V system is still running even after the car is shut off. Guess what - same happens with the standard ICE (non-EV, non-hybrid) cars! No difference here. The high voltage system should recharge the 12V battery when the car is running - just like the alternator in case of the non-hybrid vehicle. For SOME reason the DC-DC converter in hybrid systems does not supply enough power to recharge 12V battery reliably. Your video unfortunately does not explain why this is the case. Your video reasoning is bad, because what you say as the cause is actually same with the standard non-hybrid vehicles which does not have any issues with flat 12V batteries.

[@stevelitchfield]

No, no, the hybrid battery does indeed charge the 12V 'like an alternator'. And just as fast. The point you have missed from my video is that 12V batteries in EVs and hybrids are much smaller in capacity, hence they are in more danger of draining while the car is 'off'.

[@adienowed6366]

My car doesn't have all the onboard crap that this gentleman seems to have in his vehicle. It's very simple and as a result is extremely reliable. I certainly don't want,or even need,all the modern nonsense being fitted to cars these days.

[@petersimmons3654]

Cirrection: None of this applies to EVs, you can't 'jump start' an EV, it has no engine. The 12V battery is charged from the main drive battery and never dies. I've had an Nissan Leaf for 8 years and no problems with 12V battery. Think you should learn more before making videos with misinformation. It's a non problem.

[@stevelitchfield]

Sorry but you're wrong. It's just that Nissan did a good job with your car in allowing for 12V recharging when off. I wish Toyota did the same!! Overall, car manufacturers are finding ways to solve the issue.

[@UnkleSi]

This never happens with my nissan leaf. Toyota has lost the plot.

[@davidfalconer8913]

How interesting ... maybe a ( 12 Volt tap ? ) off the HUGE high voltage EV battery would overcome this ... but ... of course ... this would cause the designers ( brain overload ? ) ..... maybe ( ? ) this tiny 12 Volt battery could be recharged by a ( small ) solar panel on the car's roof ( just an idea ? ) .. please comment .. DAVE™🛑

[@stevelitchfield]

The solar one is the best idea. Make it so!!

[@alandavis2741]

It's all EVs.....I got stranded i my Jag I-Pace last week cos the 12v battery had failed without warning. A 3 year old car!!....the original battery on my Merc AMG E-Class lasted 12 years. So now I'm learning how to access the car when it's dead (my 'frunk' has an electric release, but I now know where the emergency release is hidden!), that I need to get a booster pack to keep in the frunk, and I'm going to fit a cheap bluetooth battery monitor so I can see what the 12v is up to. EVs are shite.....I have an £80,000 car I now don't trust. How many Merc S-class owners have ever fitted a battery monitor....none, I'd imagine?

[@stevelitchfield]

So how often do you actually power it up? Data point please!