PRIUS GEN3 12 VOLT BATTERY SELF TEST

While in previous Prius Gen models it was possible to read the voltage of the 12 volt battery in the Gen 3 models, 2010 through 2015, there seemed no way to do that. Its important to know the status of this battery as any failure will result in a car that won't start. Unfortunately Toyota didn't make this important info readily available to owners.
I recently discovered the procedure and wanted to make other Prius owners aware of how easy it is to check on your battery voltage.
When starting the car your voltage should not drop below 10.0V.

[@rubdulbah3201]

I swear sometimes it feels like getting my Prius into maintenance modes, is like entering cheat codes on an old video game. My thanks for this video.

[@cfldriven]

Its like they don't want us to have that information. Thanks for watching.

[@seanpop2886]

Information starts at 1:30 in (I'm here for the Gen 3 part, not the comparison to a previous generation). Thanks for posting this!

[@cfldriven]

Thank you for posting the time and commenting.

[@Leoleeartvideos]

2015 plug in Worked perfectly! It was always just waiting for it to die before knowing you need a new battery. Finally a car that tells you exactly how your 12 volt is doing without tools! Thank you!

[@cfldriven]

Agree, Toyota should have made it a one touch option.

[@NixUgriBugri]

The problem is that this is NOT telling you that much see my comment for longer explanation. What would really be good if the car would show the voltage BEFORE it started all the stuff.. the voltage is there by the way i am sure the MCU probably konws it so it could show if Toyota wanted. The only thing it tells you that NOW your battery was good enough to start the car which depends on previous state of charge (when you parked) the temperature at the time etc.

[@bartbeaudin7761]

Great instructions! A natural teacher. Thank you.

[@cfldriven]

Thank you for the positive feedback. I try to make them clear and to the point without a lot of blah blah. Thank you for watching.

[@ralphseifer5537]

I don't know if I should be angrier with you, or with myself. The app on my phone (Hybrid Assistant) kept telling me the battery on the used 2014 I recently acquired was setting on 11.4 volts. I ordered a $39 multimeter this morning, and spent most of the morning looking at batteries and prices. Then I went down to the garage, and used your technique, and in less than 30 seconds the car told me the battery was reading 12 volts. Your method acted beautifully, and I feel much less pressure now to run out and buy a new 12-volt. Of course, I'm very grateful for this tip.

[@cfldriven]

Something I learned after the making of the video is as long as the battery voltage does not drop below 10.0V the car should start. My 2014 OEM battery was at 11.38V in December. When it comes to replacing it I will get a Toyota battery because even though they cost more up front they seem to last a long time.

[@leejackson9896]

Is your car still going strong?

[@filip100000]

where can you check that in Hybrid Assistant?

[@DavidVine-DOCVIDPRO]

Excellent information! Very worthwhile video. No-nonsense, to the point and very clear directions for activating self-test capabilities. Thanks!

[@cfldriven]

Thanks for the feedback and watching.

[@77.88.]

Outstanding simple instructions anyone can follow...

[@lauraclark6182]

Thank you so much for the Easy instructions you saved me a trip from buying a battery that I did not need

[@cfldriven]

Glad to hear the video helped you with a decision.

[@brennansmith6126]

Also discovered after watching this video that I can power up car normally (with foot on the brake) and still do the [Car button + 3 headlights on-off] procedure and it will show me the battery voltage with the inverter supplying power (should be around 14v for a healthy battery). Great vid! Thanks!

[@cfldriven]

Brennan, thank you for sharing how to read the inverter voltage.

[@luisparra8530]

I will try the |"Power up normally" Car button + 3 headlights on-off] \ approach on my 2014 TOYOTA PRIUS V because the one here did not show the "Service Menu"

[@luisparra8530]

I finally got to the service menu with the car running plus Car button + 3 headlights on-off.

[@craigfones4944]

Aweswome. Worked like a charm first time in my 2012 Prius Plug in. Great information to know. My battery went out 2 years ago and I wanted to check my battery status. 12v.

[@cfldriven]

Thank you for the feedback and for watching.

[@jpthsd]

Good instructional video, I just checked my 12v battery's voltage of my 2015 Prius Plug-in, it is still at 12.2v...still good maybe another one or two years. I actually created myself calendar reminder to keep checking the battery voltage every 60 days...! Much appreciate this instructional video, save me $200 from the new Toyota battery (that's right, brand new 12v battery from Toyota dealer specifically for Prius Plug in is $200 firm)...Thus I checked my Prius Plug-in 12v battery voltage status,,,still good at 12.2v!!! Sooner or later will require a new battery but the current's still working good at 12.2v ...so avoid of spending $200 and keep using out of its life cycling then!! Thanks again!

[@cfldriven]

Pricey but they seem to last a lot longer than their cheaper cousins. Thank you for sharing your experience and insight, I though for sure this past winter would kill the battery but it still going.

[@richieryan4998]

Thanks so much! Today was the first time I've ever had a battery problem so I'm trying to figure as much on my own as I can.

[@cfldriven]

I always admirer people willing to learn more to perform DIY, congrats.

[@robk7129]

Thanks for this video and showing where to find the + in the fuse compartment !!!

[@cfldriven]

Good to hear you found the video useful. Thanks for the feedback.

[@davidbucher951]

Bless you. Winter's coming on and my wife's Prius battery is 7 years old. Just did your check and it's 11.6V. Heading to Toyota dealer tomorrow.

[@cfldriven]

Hope the visit to the dealer didn't sting too much. Thanks for the view.

[@leiferiksson1785]

David, it is not that simple. If you e.g. are only driving short trips daily, you might end up with a badly charged battery that is actually fine. You have to charge for many hours to fill it up, or drive for many hours. And you do not need much to start the cars as the engine is actually started from the high voltage battery, not the 12 volt.

[@eCroz_8611]

@@leiferiksson1785 I was under the impression that the 12v battery is needed to initialize the computer. After a self check it switches to the HV battery. If that's the case, the question now is, how much voltage is required to initialize the computer? 12v? I have a 2011 prius 2 without the advanced display, so I'll try the multimeter method

[@leiferiksson1785]

@@eCroz_8611 does not need much but close to 12v. If you max the 12v battery you will get more like 13v. If you live in a cold are with below water freezing point, then a badly charged battery may take a lot of damage.

[@chainring]

This procedure worked with my 2015 Prius C. However, I have a key instead of a Power button. If you have a key, turn it to the Accessory position, wait for the usual initialization screens to finish, then follow this video's instructions.

[@cfldriven]

Thank you for sharing your insight on the Prius C.

[@robk7129]

You made my day 😊. Battery was down, too many short trips during this winter period… I was able to start my car with a portable battery booster (amazing piece of equipment). Initially I couldn’t find the + connector. Now back on track. Thanks 🙏

[@cfldriven]

Glad you were able to get exactly the information you needed and get your car safely started. Now time for a longer drive.

[@cameronsimonton2515]

Clear, concise, to the point Well done! To clarify - when pushing the "Start Button" you ARE NOT stepping on brake pedal? Correct? Thanks!

[@mlw771]

on 2010 I used the InfoPhone button and held it down while I turned lights on and off and all worked as written...thanks.

[@cfldriven]

I was thinking maybe another button did the same function but had no idea which to suggest. Glad you figured it out and that you shared the solution. Thank you.

[@eriklawrence4652]

I had the same on my 2011

[@kimberlysuzannemoore]

Omg I have a gen 2 but I didn’t know this could be done and watching your video now I know we can and I also know I could take a small vote reader and hook it up to the front of the car and bring it through the dash so I could have a continuous reading I don’t know if that would be so smart..

[@cfldriven]

Not if the meter is on all the time. Since the battery is there to start the traction computer there no need to check voltage all the time. Apparently if starting voltage remain above 10 volts the car will run. If you get to that point it probably a good idea to shop for a replacement. Our 2014 is still on the OEM battery.

[@nishrover]

Great Info. Thanks for the Post !!

[@cfldriven]

Thanks for watching.

[@clubquarantinerelief2522]

Sir you are a legend!

[@cfldriven]

Actually the Mrs calls me something else, but your kind words are appreciated.

[@yichengcheng839]

Worked with my 2015 Prius. The key is you need to keep holding the car button while switching the lights.

[@cfldriven]

Thank you for sharing about the 2015.

[@4LSav]

Hi do you know what button to press if I don’t have car button ? I have navigation options

[@seanmahoney196]

@@4LSav me too

[@ChrisCoCreated]

You beauty! That did it on my 2012 plug in

[@fitsumaberra5043]

Thanks for a very informative video. I've one question though, can I check the hybrid battery the same way with the engine on?

[@cfldriven]

This procedure will not allow you to check the hybrid battery only the starting battery. However there are some OBD readers that can, thus saving you the cost of the dealer checking it.

[@iansmith7286]

I have a cheap ELM327 OBD II reader that I use with my phone and the "Torque Pro" app. There are "PID Codes" specifically for the Prius that will allow you to read the hybrid battery info showing each individual cell. Here's a video showing how to add the Prius PIDS to torque pro. kzbin.info/www/bejne/fYrVpJ-wl9eqsJo

[@user-rw8qt7jf3q]

Thank you for this!

[@cfldriven]

Thanks for watching

[@jayinla228]

Great video, if you did have a multimeter what setting would you use to test and what number would means it's good? Thanks

[@cfldriven]

Set the multi-meter selector to 20 volts DC. Depending on meter your choice may only be DC. When turning on the car, the voltage should not drop below 10.0V. Our 2015 is still running on the original battery.

[@user-kf1sh8to9k]

I have a 2015 Prius. This year does not have a 'car button". Any tips?

[@HitMan1515]

Good video!!

[@cfldriven]

Thank you so much!

[@Sunnysky321]

You can check it this way, but that number alone won't tell you much about the health of the battery. Go and measure directly at the battery terminals, and you will see a higher voltage. Typically this difference is about half a volt. So you need to know what this difference is for your car.

[@stefanmunteanu66]

On Prius T Spirit 2010, same steps but press the DISP button as there is no CAR button. However the menu differs and it doesn't display the battery V

[@cfldriven]

Thank you for sharing this useful information.

[@littleleapling]

My 2012 Prius 12V reads 14.4V today. I replaced 2.5 years ago after coming back from a 3-day trip to a dead car. I just came back from a 4-day trip to a dead car. If the System Check Mode reads OK and the battery is fine, what do I try next to figure out why my car keeps dying when not used for a few days?

[@cfldriven]

The Prius and many other cars continue using power after being turned off, although 4 days is awfully quick. Was the vehicle locked, on my e-Golf that reduces the current draw as the electronics are monitoring less. If you do many short trips, that doesn't allow enough time for the 12 volt battery to be topped off. You could consider a small trickle charger for when you are gone.

[@TheMeaninglessName]

I did this check on a 2010 (using the InfoPhone button),and it showed 11.4 volts. I replaced the 12V battery and the new one showed the same reading, or sometimes 11.3 volts, even after several hours of driving/charging. So I tested the old battery with a volt meter and it showed 13.4 volts. I then tested the new (still installed) battery at the fuse box terminal - 13.4 volts. So I'm not sure what this check shows, but as presented it doesn't seem to be a good indicator of health of the 12 volt battery.

[@dailoman]

Any update on this? I'm curious.

[@Always_sojourning]

Good stuff!

[@cfldriven]

Thank you for taking the time to watch.

[@simplyraw1369]

Omg! Thank you kindly!!!

[@cfldriven]

Thanks for watching.

[@EgaTehPro]

Woowww!! Thank you!

[@taimoorkhan8881]

My Prius 2014 showing engine sign so can i change the battery or hybrid battery ?

[@cfldriven]

If it's the check engine light. ... It could be a misfiring engine, a broken oxygen sensor or simply a loose gas cap. While not a pull to side of road and call tow truck event, it should get checked out as soon as possible. Do check the gas cap first it case it loose.

[@bbqpotato9793]

Thank you!!!

[@cfldriven]

Hope you found it useful. Thanks for watching.

[@bbqpotato9793]

@@cfldriven it help a lot!

[@ricpratt6584]

I have a 2013 Trim Level Five (not the V wagon) with the Tech Package which has a different upgraded radio which has no "Car" button to push. Also, the radio screen does not light up or turn on at all after pushing the Start button twice. How do I access this maintenance/system check feature then?

[@cfldriven]

Don't know if this will help but Mrswann Shiran mentioned, Try display button instead of car button, good luck

[@ricpratt6584]

@@cfldriven Thanks for the reply, but there is no "Display" button either. Any other ideas?

[@cfldriven]

@@ricpratt6584 Ric sorry to say I don't, maybe someone reading the comments has a suggestion.

[@eileenocb]

This didn't work for my 2015 Prius C and I definitely held the Car button while I turned on the lights. Tried the lights 3 times and 4 times but only get "Audio Off" on the screen.

[@cfldriven]

Thanks for sharing your results with the Prius C. If you discover a way let us know. Thank you for watching.

[@mraaronfrancis]

I have a Gen 3 prius without a mfd screen, is there anyway to get to the service menu?

[@cfldriven]

Aaron don't know of a procedure without the use of the screens. Maybe someone will share thoughts on this question. Thank you for watching.

[@SIMULATIONHIGHTECH]

Thank you

[@cfldriven]

Most welcome! thanks for watching.

[@dabakrada5077]

Is 14.6 volts too high on a brand new battery while my gen3 prius is running? I just want to be sure its ok. Thanks!

[@cfldriven]

When the car is on, the onboard inverter is charging the battery, thus the higher and normal voltage.

[@Tom-cn4cm]

Nifty solution...for those with a screen.

[@cfldriven]

Or you can opt for an inexpensive volt meter.

[@iansmith7286]

Thank you for this. Picked up a used 2013 Prius. I've been getting around 6liter per 100 km and slowly getting worse. Checked my 12v and it's at 11.7v. I'll replace it today.

[@cfldriven]

Depending on type of driving, season, and terrain this mileage maybe on the low end. Unless you have very cold winters you might be able to get another year or so out of the battery. Our 2014 OEM is still running strong. You may want to have the traction battery checked to see if any of the cells need to be replaced and if it still under warranty. In the US it can vary from 8 to 10yrs or 100,000 to 150,000 miles.

[@iansmith7286]

@@cfldriven Thank you. I tested the battery today at Lordco (similar to NAPA), and it showed as just needing a recharge. I pulled it from the car and charged it for 2 hours at 2amp max until it was full. Went out for a 20 km test drive this evening and the car computer is showing 4.8L / 100km (49mpg) from 6.8L / 100km (35mpg). The battery is now showing 14.5v rather than the previous 11.7v. I'll keep an eye on it and report back if it continues to show the improvement or if it goes back to the lower mpg. I drive a lot of short trips around the city so it may require an occasional charge out of the car to keep the battery topped up. I hope not, but if that is the case, I'll need to pick up a memory maintainer to keep my trip computer info. Lost the data when I disconnected the battery. It will probably take a week or so for the computers to relearn how everything is running.

[@cfldriven]

@@iansmith7286 Short trips can lead to voltage drop as the inverter doesn't have enough time to top off the battery. Mrs also has short commute under 3 miles, but weekend drives are enough to get the battery back to normal. You may want to consider a 1 amp charger/maintainer that doesn't involve disconnecting the battery.

[@iansmith7286]

Thank you. I'm going to pick up an amp meter to confirm the inverter is charging the battery. Then I'll take it out for a long drive to see what happens.

[@cfldriven]

@@iansmith7286 Don't forget you can use the connections in the engine compartment fuse box (about 0:43 in the video) to get a reading instead of opening up the battery compartment in the hatchback. Best of luck.

[@yousjebari6951]

My UK model doesn't have car button. Do you know what other button it might be?

[@cfldriven]

In some of the comments people have had success using the display or phone button.

[@rondhole]

I doubt you need to replace the battery. In Prius, the 12V battery are often below 12V, the main point is to test it under load like turn the headlight on and see how much it dives to lower voltage. As long as it is higher than 11.V under load with headlight on and blower motor on, it is still good.

[@cfldriven]

Thank you for sharing the info. I learned a bit more after making the video. From Toyota mechanic; battery should be at 12.6 volts when starting voltage should not drop below 10 volts. Since this battery only has to get the computer going, it can a long time before needing to be replaced. We're still on the 2014 OEM battery.

[@rondhole]

@@cfldriven yes, it is true for regular cars , non hybrid. Voltage alone is not enough, you need to load test it and see how much voltage drop. As AGM battery in hybrid is deep cycle, sometime the voltage below 12V but it last really long. 7-9 years in most cases. My battery often just below 12 V and I test load it by turning the ignition, headlight and blower, but the voltage is still above 11.4V. It has been like that since 4 years ago. It is alrewdu 6 years old and still runs just fine. With a toyota, don't fix if it is ain't broken.

[@cfldriven]

@@rondhole Thank you for sharing all this good information.

[@rondhole]

@@cfldriven open circuit will always shows above 12V , usually about 12.3V. But when you press the power button without pressing the brake, normally it will drop to about 11.7V. Turn the headlight on 11.3V, defroster, blower motor max heater on, it can drop further but still above 10V, you are safe. Bad battery often shows below 10V when the ignition is on. Under all load it drops to 8V. Below 10V when ignition is on, you often cannot even unlock the door.

[@cfldriven]

@@rondhole Adding these numbers to the inside of the manual for future reference. Thanks again.

[@chainring]

Is it important to stay off the brake pedal during this test? So the car does not start after the first Power button push? Thanks, great video!

[@cfldriven]

Having the engine starts means having to shut it off and redo the steps. Thanks for watching.

[@caseykittel]

@@cfldriven so no brake pedal at all right?

[@cfldriven]

@@caseykittel You are correct, at no time did I ever press on the brake pedal.

[@NixUgriBugri]

@@cfldriven but just opening the driver side door will "charges up" the main break cylinder you can actually hear that ... THAT is the biggest hit on the 12V battery so even a medium/good battery will drop the voltage considerably. If you are interested in the real open current voltage of your battery you MUST do it at the back on the battery itself. The fuse box you may have a slight voltage drop. And if the car already booted up you are NO longer measure the open circuit voltage which is real test for a battery .... (after a few hours of an external charger or a long enough drive). What you show is pretty much useless test .... actually 11.9V after the break cylinder charge and a load, is NOT too bad at all I have seen 10.9 with that ... what is not happening is the inverter charging the battery. You can actually perform this (did not try) NOT opening the driver side door but passenger side (but of course much harder to do ... Try that and see if the numberes are the same also putting the car in auxiliary mode alone puts load on the system. So this is useless (even if it works)

[@cfldriven]

@@NixUgriBugri Thank you for sharing your knowledge on the subject, always good to learn more.

[@AgentAaron2]

How do you do this if you don't have navigation? There is no screen; all the vehicle info appears above by the speedometer. 2010 model. Thanks!

[@cfldriven]

The 2010 Prius has the same layout as the 2014 so the steps in the video should work. If your display monitor is not working then I would just get a voltage meter and get a reading from under the hood.

[@bobhubel1]

@@cfldriven Like Aaron (above), I also have a car (2011) without that large screen and I do NOT have a "CAR" button. There must be an alternate button to use on mine. Do you know what that is?

[@froggyhigh101]

@@cfldriven I also have a 2011 Prius and there is no screen in the middle. All info appears on dashboard.

[@great2c4me]

@@bobhubel1 did you figure it out ? I have a 2010 also with no "car" button

[@great2c4me]

@@froggyhigh101 did you figure it out ? I have a 2010 also with no "car" button

[@Propain4eva]

When I turned the car engine on, that 12v voltage changed to a higher voltage. Is that the hybrid battery?

[@cfldriven]

Yusuf, the higher voltage is from the DC to DC convertor that charges your 12V battery. The DC to DC is feed from the traction high voltage battery pack since the car doesn't have an alternator.

[@heather23renae]

Got a brand new battery installed after seeing low voltage from the diagnostic screen and having it tested at autozone. New battery is reading at 11.5v 😢 on the diagnostic screen so now I’m worried there’s something else going on with my car

[@cfldriven]

I am still on the 2014 OEM battery and I have discovered as long as the voltage does not drop below 10.0V the car will turn on.

[@horrerahashmi8306]

Thanks for this. Told me what voltage my battery is on. Is 11.8V good for my second hand Prius that I have 145k kilometres on?

[@cfldriven]

A fully charge battery should read 12.6 volts, this display will typically measure 0.2 to 0.3 volts lower then the battery is, as it does place a load on the battery. Depending on your typical driving pattern (short or long) and temperature exposure are factors to consider. Our 2014 OEM battery started the car last week with temps in the low teens. We have a very short daily commute, but weekend errands make sure the battery gets topped off. If I were you I would just keep monitoring the voltage level and if it continues to drop below 11.5V you may want to opt for a replacement.

[@horrerahashmi8306]

@@cfldriven alright thanks. If it helps, I drive the car 200+ kilometres per daily. And it is a 2015 Prius

[@cfldriven]

@@horrerahashmi8306 With that kind of daily mileage you battery won't die due to insufficient charge. We're 6yrs on the OEM and will probably replace this summer for piece of mind. Will go with Toyota battery as its designed with correct internal resistance for the charging system and if it anything like the OEM I'll get another 6 years.

[@donmiguel1513]

DID YOU END UP HAVING TO REPLACE BECAUSE OF IDIOT LIGHTS ON. MINE HAD A WARNING OF CHECK HYBRID SYSTEM

[@heatherdavis5772]

Is there a procedure to figure out whether it is the 12v or the Nimh battery if it is dead?

[@cfldriven]

If the aux battery is dead than nothing will work. If the traction battery is dead the starting sequence will work.

[@samtx]

my 2010 prius doesnt have that display screen nor car button ,anyone know if its separate process for my model prius 2010

[@nicolecuellolao3025]

Hold down the “info phone” button instead of the car button as shown in the video. Worked on my 2010 Prius.

[@antaraanisa]

Hi I live in 🇬🇧. I have gen 3 2010 model. I don’t have the car buttons. What shall I press?

[@cfldriven]

Hopefully someone from your side of the pond has experience with this and can answer. As alternative you could get a voltmeter and read the voltage from the front terminal fuse box or directly from the battery.

[@touheyprod]

My 2012 prius shows 14v when I checked the battery today. Is that a high number that suggests a replacement is near? I notice my MPG is much lower now, I get 30-35mpg normally. Prius has 195k with battery and head gasket replaced ~ 150k. Thank you

[@michelgarciag]

I would like to see what you get as an answer here. I’m considering changing my 12 V battery because I’m averaging 43 MPG I don’t think it is normal.

[@gisk7846]

I think the drop of MPH is related with the decrease of main battery modules's efficiency instead of 12V start battery. In my experiences of various batteries, both 14V and 11.9V would be fully fine. I would be serious about a battery when there is over 0.4 ~ 0.5 V drop of voltage. So to speak, from 11.6 V Additionally, less than 3 V higher voltage would be also fine.

[@NixUgriBugri]

Most likely the car was in Ready mode so the system was already charging the battery. It is doing it at about 14V somewhere btw 13.9 and 14.2 V (until it is re-charged) .. I can tell since I have a ScanGauge monitoring the battery voltage among other things. The only really good (simple) test for a battery is to measure the open circuit voltage after some time the car stopped AFTER at least for an houre drive (wait several hours if possible). Best it is at the back under the hatch ...under the hood is OK but you cannot open the hood without opening the driver door which then triggers the main break cylinder initial charge up. That is a huge load on the battery ... If you have a garage open the hood at the evening (just unlock it) and measure the voltage as it shown in the video that is a good home test. Better yet to take to a place where they can measure it with a tool much more reliable.

[@rondhole]

There is no logical correlation between 12V battery and MPG. Unless the battery is really bad and the DC to DC converter keep charging large current that is wasted as heat. But not so much heat that can take MPG that much. Only in warm weather >12V is a good parameter in open circuit, not when the ignition is on. . In cold weather below freezing, the best number is not the maximum voltage but the voltage reading under load. As long as it is above 11 V when the ignition is on, it is OK. If the headlight+heater/defroster+AC blower are all on, it should be still above 10V. This is the best parameter, not the voltage without any large load. Bad battery often shows ?>12V and drop under 10 V, often as low as 8V when under load. I have mine at 11.7V when ignition is on, it does not have problems for the past 4 years starting the car. My old bad battery reads 12.2V open circuit but when under any load it drops well below 10 V. That death battery was 7 years old in hot Florida without garage.

[@alucardhellsing6003]

For models with no "car" button, you press Info, and you activate this while car is running normally.

[@depresseddiaryyyy]

The procedure didn't work for my 2014 plug in Prius. Followed everything in the video and only got the screen after pressing the Car button

[@cfldriven]

Interesting, that a plug in would work differently. Maybe another plug in user can also share their experience. If you have a multimeter, measurement can also be made from the fuse box in the engine compartment.

[@zafarsongs]

The procedure is not working in my 2011 Prius 4. Can you help me please?

[@cfldriven]

I would try switching the headlights on and off four times instead of three. Hope that helps.

[@abdullaharslan1318]

how accurate is the voltage displayed? When I measure externally by multimeter I ve 1-2V difference. I.e it shows 10.5 when the car is off and 11.4 after a drive but I myself measure 12.3

[@cfldriven]

After driving the battery has been charging so not surprising to see a higher voltage. The diff between measuring at the battery, or the engine fuse box is due to cable length and electronics, as the Prius is never truly off. Best reading off of battery is couple hours after driving or first thing in the morning without turning on anything, keep fob away. Thanks for the view.

[@abdullaharslan1318]

@@cfldriven Thanks

[@TheMikeborecek]

My prius 3 show 11,9V on new battery. When I make measure with my voltmeter - car was off - 14,3V what is 2,4V difference. What means that it si very good conditions of my new battery. Now I buy a bluetooth checker battery, which will show me when is my battery low and when I have to charge it. I think this is the best solutions how to check battery premanently.

[@cfldriven]

@@TheMikeborecek Thank you for sharing your insight on voltage differences between load and no load when testing a battery. The confusion occurs that the off car batt at 14.3V only shows 11.9V when used to start the car. What is the lowest voltage the Prius needs at the electronics to start the car as it never see the 14.3V?

[@rondhole]

The battery in this video is perfectly normal and in excellent condition. Only in warm weather >12V is a good parameter for open circuit (ignition is off). In cold weather below freezing, the best number is not the maximum voltage but the voltage reading under load. As long as it is above 11 V when the ignition is on, it is OK. If the headlight+heater/defroster+AC blower are all on, it should be still above 10V. This is the best parameter, not the voltage without any large load. Bad battery often shows ?>12V and drop under 10 V, often as low as 8V when under load. I have mine at 11.7V when ignition is on, it does not have problems for the past 4 years starting the car. My old bad battery reads 12.2V open circuit but when under any load it drops well below 10 V. That death battery was 7 years old in hot Florida without garage. 14.4V is only when the car in READY mode, DC to DC converter works as alternator charging the battery.

[@sueellenmcgoey8708]

Ty! 12.3 good

[@cfldriven]

Thank you for watching.

[@GEAUXFRUGAL]

Wanted to know how my hybrid battery was doing.

[@cfldriven]

I know of three ways of testing the hybrid battery, which I have never done, one is to have the dealer test the battery, a cheaper route is try a ODM with an app like DrPrius, and finally look for telltale symptoms like drop in mileage, engine running all the time, battery not holding charge.

[@TerryUniGeezerPeterson]

There is no "car button" on my 2011 prius.

[@horrerahashmi8306]

Look for vehicle or a digital button somewhere

[@TerryUniGeezerPeterson]

My 2011 does not have a display like that

[@mrswannshiran64]

Try display button instead of car button

[@nicolecuellolao3025]

On my 2010 Prius I held down the “info phone” button. I hope you have one of those

[@mlw771]

I don't have a "car" button on my 2010 prius??

[@cfldriven]

How interesting since your model is a Gen 3. Wondering if they added later in the production run.

[@nikamiqava]

2014 prius, it doesn't work, any tips ?

[@cfldriven]

Sorry this is the only way I know to do it. Other options are to borrow volt meter for automotive parts store or purchase an inexpensive one from Harbor Freight.

[@lil_bear]

Mine reads 12.1 does it need to be replaced?

[@cfldriven]

When turning on your Prius, the battery voltage should not drop below 10.0 Volts.

[@donabrams5741]

You can also check the 12 V battery with a multimeter in the cigarette lighter

[@cfldriven]

You may get a slight difference due to the electronics it going through. You want to use an obstructive path from battery. Best is to measure the battery directly if possible.

[@rondhole]

No, the reading is actually identical. about 12.4V open circuit, about 11.7-11.9 ignition on (2x power button without braking). 14.4V in READY mode. But only if your Voltmeter is actually good.

[@taimoorkhan8881]

Which battery I can install it 46 50 or 60 ?

[@cfldriven]

You need an AGM battery, best to get from the dealer (shop around for price) since it designed to have the correct internal resistance for your car. You can find other AGM that will fit and work but they are still expensive so might as well get the better one. Good luck.

[@taimoorkhan8881]

cfldriven Thankyou so much bro ❤️

[@angryaardvark2124]

I can’t get it to work on my 2013 Prius iii. 1. Press power button 2x 2. Press and hold Car while turning headlights on and off 3x. 3. Let go of Car button

[@cfldriven]

In the comments are a couple of 2013 that had success with this procedure. You might want to try switching the headlights 4 times as those were the instructions I found. It just so happens that when I did 3 it worked so I went with that.

[@radrcer]

I dont have a “car” button on my gen3

[@alexisdaniellewebster105]

Is there a way to determine the battery life of a used prius? Without buying a reader and using dr prius app

[@cfldriven]

No unless you go to the dealer and have a friend with access.

[@alexisdaniellewebster105]

Thanks I bought a 2015 prius two yesterday for 9100 cash 81k miles pristine condition. I was able to check the 12v battery cause of you. I'm happy with my purchase and next week toyota dealership will service it rotate tires and let me know if anything else may be needed. Gonna have them check the battery. But it runs so smooth I wouldn't think it would need a new battery yet.

[@cfldriven]

@@alexisdaniellewebster105 Nice going on the purchase. The gen 3 is still my favorite, don't like the "new" look Prius. If the owner didn't get the software updated, the dealer with take care of it since it was part of a recall. We drove ours three times cross country and bypassed a lot of gas stations. Enjoy.

[@rondhole]

The easiest parameter is reading the internal resistance of the 24 cells HV battery. You can use capable ELF327 scanner with Dr.Prius apps. Carista is one of them. Dying battery has large internal resistance and usually much larger than the rest of other cells. Usually only one or 2 cells are bad but the rest are on the way too. Typical gen2 or gen3 battery last about 11 years in hot weather and well beyond 15 years in mild weather or when it is garage kept.

[@danielrappa4258]

My 2010 has no "Car" button. ??

[@drappa2109]

Try the "info phone" button on my 2010 Prius Model 5 and that brought up the function check settings button and pressed the vehicle signal and saw the battery voltage. Just put a new one in and it's 11.6v?

[@Tommy_TwoShoes]

My 2013 does not have the car button either but it works with the setup button same procedure

[@AgentAaron2]

In my 2013 Prius V I had to do the headlights on/off 4 times.

[@cfldriven]

Thank you for sharing that info. Interesting how different models levels change what one would think was universal for that particular generation.

[@abonnema]

There is no 'car' button on my audio display. 2010 prius

[@cfldriven]

What if you try the button in the same position?

[@mrswannshiran64]

Try display button instead of car button, good luck

[@nicolecuellolao3025]

The info phone button worked on my 2010 Prius.

[@cfldriven]

@@nicolecuellolao3025 Thank you for sharing this tip with everyone.

[@physicalivan]

what about gen 4

[@cfldriven]

The procedure seems to change with diff models to gen. If you discover a way let us know. Thanks for watching.

[@GEAUXFRUGAL]

Power 2X car button hold down and headlights on off 4X

[@gotaigo]

Don’t have a car button in my 2011 3rd gen

[@cfldriven]

Have you tried the button in the same position?

[@goblue7516]

Aren't you supposed to check it with it running

[@bsquare111]

No - because it will be charging then & give you a misleading reading. You need to know the battery voltage after the car sits for at least an hour. You want to see if the battery is holding it's voltage once the charging has stopped.

[@goblue7516]

@@bsquare111 mine was 12.1 resting so thats ok right

[@NixUgriBugri]

@@bsquare111 that is exactly right !!! and measure before the break cylinder initiation....

[@pbandjwrx]

Ok so what if I don’t have a screen like yours.

[@cfldriven]

While this video is specific to the Gen3, one can always purchase an inexpensive voltmeter and get a reading either from the battery or from the fuse block. Harbor Freight has one for about $7 www.harborfreight.com/electrical/electrician-s-tools/multimeters-testers/7-function-digital-multimeter-59434.html

[@NixUgriBugri]

This is great that you can do this. BUT this is USELESS to figure out if the 12V battery is in good or not so good condition. Just opening the driver side door will hit your battery hard (notice that buzzing sound ? that is pre-charging the break cylinder, the biggest load ! during the start up of the car) and you turn on the CAR even in auxiliary mode will take even more charge out of the battery. The only real test is to measure the battery open circuit after charge was completed for a few hours (basically stop the car and let it sit). Same issue with the under the hood measuring, either you have to leave the hood un-locked after you stop the car so you DO NOT open the driver side door or get into the car from the right reach over to open the hood. However you can open the hatch without any of the previously mention problem and you FINALLY CAN measure the voltage of the open circuit "rested" 12 V battery. (this better than nothing but if you really want to know the battery "health" you need a real battery tester many places will perform this for free) If you cannot bother to buy a multi-meter why bother with the rest ... again what the car show IS the voltage but it is useless at that point to assess the 12V battery actually 11.8V could be just fine by the way. Not great, if that is the rested voltage then it is definitely bad news. But that is NOT what you measure with this procedure.

[@cfldriven]

Thank you for sharing you insight. Yet its the voltage under load that determines whether or not the vehicle will Power on, you still have to open the door to get into the car in order to switch it on. For those without access to a multi-meter this procedure provides some information.

[@NixUgriBugri]

@@cfldriven ​ @cfldriven Sorry you are mistaken, this is not the way a 12V battery tested (self tested). This is the voltage of the 12V battery after all the steps booting the car and you can keep watching it if you choose until restart again. Educational but nothing to with battery "self test". This voltage again means very little (I am not saying nothing). It will heavily depend what happened to the car especially the 12V battery prior to this test. If the car was driven 30-40 minutes at least before parking it (then waiting for the test 2-3 hours at least so 12V battery charge settle) then, you may have some useful information, because then you can assume the 12V battery was more or less fully charged (if the battery still OK state). Otherwise you would start the test from an unknown state. I guess you can believe what you want but other people may take your advise how to "self test" the 12V battery. If you want meaningful test result you would need to fully charge the battery (either by driving your car long enough, or some external charger), let it rest a few hours and measure the open circuit voltage that will give a realistic view of the battery "health" you can also compensate for temperature etc. What you show is hey the car still started up, now I can measure the voltage afterword ... could be very very misleading. If you want to measure the car battery under load which is an even more realistic way to check the "health" of the battery, you would need even more than a multi-meter. Again this is a good test if you can get it done will tell you a lot (how long you can expect the 12V battery to last) If you are concerned of the 12V battery, let me suggest to get one of those smart/trickle charger (not too cheap a 1A or 2A is enough) and charge the battery up time to time. Especially if the car sits a lot (during Covid or otherwise). You have a garage (judging from the video so this should be a non-brainer). What you can easily tell from your own experience that just starting up the car and get to the point you can measure the voltage, a LOT of charge was pulled I explained before, this "low" voltage 11.8V is due to the realtively small size of this prius battery... but this is NOT unusual at all.

[@user32186]

My car it doesn’t have the car button.

[@yordangrozev7843]

Yes, mine neither, what do I need to hold in this case?

[@jamesalles139]

get a 4 amp charger that has an AGM setting from Harbor Freight. Charger that battery with a smart charger as a routine maintenance item. You happy Aux battery will thank you by having a longer life.

[@cfldriven]

James, I agree some regular battery maintenance can add to battery life. I actually got the Cat kzbin.info/www/bejne/fqDbfWiJq9CWadE which works with 3 types of auto batteries. Thank you for sharing.

[@mattwernecke2342]

I couldn't get it to work

[@cfldriven]

Matt, in that case, a cheap voltage tester can be used.

[@jacka.4774]

this method did not work for my pruis V 2015

[@cfldriven]

Sorry to hear that, did you keep holding the car button while switching the lights? Thank you for sharing your experience.

[@jacka.4774]

@@cfldriven my car is Prius V III 2015. I did not find a car button. but I tried it with all the buttons around the radio.

[@cfldriven]

@@jacka.4774 Sorry this solution did not work for the Prius V, if I learn anything new I will pass it on.

[@jacka.4774]

@@cfldriven thanks

[@ajbrown2013]

Why not just check it the east way?

[@cfldriven]

Each person can decide what is easiest for them depending on equipment and time.

[@joeshmoe8952]

My battery says 14.6V is that ok?

[@cfldriven]

That is outstanding! Just like new.

[@joeshmoe8952]

@@cfldriven I was confused because I thought it should read 12v but I’ll take the 14.6 lol. I purchased the car in Jan of 2019 & it’s got 83k as of now. I’ve babied this car as if it was a luxury sports car but I do that with all my cars. Hoping to keep this car for as long as it runs.

[@joeshmoe8952]

Thanks for the video by the way, it really helped me. Only problem I have now is I’m debating if I should return this Alpine touchscreen head unit I bought because I just realized I would lose the self diagnosing option with the factory radio. I do have a yellow meter where I can check from the fuse box so that wouldn’t be a problem for me but I know there’s other options I would lose.

[@cfldriven]

@@joeshmoe8952 A fully charged battery will typically display a voltmeter reading of about 12.6 to 12.8 volts, if the car is on the voltage would be in the 14v area. This is due to the DC to DC inverter charging the batter.

[@joeshmoe8952]

Hey there, I'm back again with a quick question. I tested my battery today with the method you showed on the video. I popped open the fuse box and used my fluke meter. I have an aftermarket radio so the factory radio option is not available for me. I tested the car when it was off and it read 13, when it was on 15. Are those ok numbers? Reason I ask is because I had a coupon for a dealership oil change and they told me my battery was going bad.

[@BirdyVlad]

FOR 2010 HOLD INFO•PHONE BUTTON!!!! WORKS!!!!!!

[@cfldriven]

Thank you for sharing the tip.

[@alienvampirebusterswhoyoug8257]

Won’t work on Prius V

[@cfldriven]

Sorry to hear they changed the way to access the battery reading in the V. If you find a way let us know so we can share with the other V owners. Thanks for watching.

[@alienvampirebusterswhoyoug8257]

@@cfldriven very annoying the V was discontinued and not very popular no idea why this wont work on it thanks

[@cfldriven]

@@alienvampirebusterswhoyoug8257 But you still have great mpg and low maintenance. For a hatchback our Prius can haul a lot, would imagine yours hauls even more.

[@alienvampirebusterswhoyoug8257]

cfldriven reason I bought it hauls everything

[@SIMPLEGUY423]

I have same car 2012 Prius I tried did not work

[@cfldriven]

Sorry, maybe the code is different for your model year. I was told it was the same for Gen 3 models.

[@SIMPLEGUY423]

Got it tested in autozone it’s said bad battery just bought a new one thx

[@cfldriven]

@@SIMPLEGUY423 Good to idea to get it replaced before it leave you stranded.

[@johnfitbyfaithnet]

I have a 2011 with no screen

[@toastyghostyofdeath3909]

real life cheatcodes

[@cfldriven]

Thanks for watching.

[@toastyghostyofdeath3909]

@@cfldriven just tried. Total work. But it has less options than yours.

[@stevefreier2156]

I just tried this and it worked the first time perfectly! The battery showed 12.2 volts. However, I tried it a second time and NADA! Then I tried to actually start the car - a 2013 Prius - and now the car is totally DEAD! No lights or power at all! WTF? How do I get it back to normal? UPDATE: 3 hours later: I was lucky I had a spare 12 volt AGM battery which was still good, so I swapped it out when I found the installed 12 volt battery had somehow gone bad right after the test! It measured under 1 volt after I took it out and something like 74 volts when still connected! I have no idea what exactly happened to blow this battery out. And it was insatlled new just 14 months ago! Bottom line: I don't think I will be running this "self test" again!

[@cfldriven]

Steve, just displaying the battery voltage will not do anything to the vehicle. I have never played around with the other settings so not sure what they can or can not do.

[@stevefreier2156]

@@cfldriven I don't think the battery self test was the issue that caused the battery to die. Although I did run it two times. Then after that the car would not start so I tried everything I could think of to get the lights to come on the dashboard. After that I even jumped the car with a battery pack and still nothing. So whatever it was I cannot tell!

[@fuentes8503]

I don't want to go through that,??? Why not, you sound like a guy that probably has a voltmeter laying around, not everyone has a monitor display

[@cfldriven]

LOL, yes I do have a voltmeter laying around, but not all Gen 3 Prius owner have one, but they all have a monitor display. Thank you for commenting.

[@bobnovak5387]

Replace 12 volt battery with OEM Toyota brand..... Mine was 220 at the dealer...... Took about 25 minutes to install myself first time.., don't trust all these aftermarket batteries with all these electronics in the Prius.

[@cfldriven]

I agree with you the OEM matches the resistance specs the DC to DC charger is built for. Even at $220 it still a bargain considering our OEM is 8 yrs old. Thank you for the info.

[@rezkrezk9680]

Did not work on my 2014 Prius three