12v battery maintenance, issues, etc.

[Mooly]

41 minutes ago, anchorman said:

It’s all well and good knowing what might cause it and what tests can be done to substantiate battery health but 99.9% of owners just want to own and drive the thing when they want to.

Exactly, at the end of the day you want (and should expect) something that just works. The myriad threads and posts on these issues show that goal hasn't been met and yet there is no definitive reason as to what is going wrong.

It would be so easy to rig a test vehicle up with a current monitor (measuring voltage just doesn't really cut it here) and log the discharge rate over say 7 days. I've never seen anything like that published.

Its pretty obvious that this Battery issue is widespread across not just Toyota but other makes and models as well. There is nothing to beat 'customer usage' to find out design defects that just don't show in design and development despite months of testing and millions of miles covered in development.

I don't believe there is a easy fix for this although I would bet next generation vehicles will be much improved. Low power (micro power) design of the background electronics is what is needed possibly along with a more aggressive charge regime when it is in use.

42 minutes ago, anchorman said:

Come on Toyota, take responsibility.  

That is what needs to happen.

 

[Max_Headroom]

Quote

It’s all well and good knowing what might cause it and what tests can be done to substantiate battery health but 99.9% of owners just want to own and drive the thing when they want to. 

If you drive an ICE car infrequently and do not do many miles when you do drive it  the Battery will  eventually let you down, the Hybrid 12v Battery is much smaller than an ICE vehicles Battery and from what i have read in the thread the Hybrid system doesn't charge it as fast as an alternator in an ICE car i dont believe its a *bad battery issue i believe owners having these issues simply dont drive them enough.

*obviously some cars will have duff batteries but that will be the minority.    

[Max_Headroom]

1 hour ago, Mooly said:

It would be so easy to rig a test vehicle up with a current monitor (measuring voltage just doesn't really cut it here) and log the discharge rate over say 7 days. I've never seen anything like that published.

I thought there were many examples of this posted in the thread.

[Roy124]

A thought on prevalence. 

Many people come to this forum when they have a problem.   Many no doubt have problems but don't come here.

What we don't know is how many neither have a problem nor come here.

It is likely that what we see are skewed figures. 

[Graham47]

1 hour ago, Max_Headroom said:

i believe owners having these issues simply dont drive them enough.

How then do you explain those ‘low mileage’ owners who haven’t had problems or those ‘higher mileage’ owners (mainly appear to be around 21-22 MY) who do ?

 

1 hour ago, Max_Headroom said:

*obviously some cars will have duff batteries but that will be the minority.    

Do you have figures to back this ‘statement’. (See above).

[Max_Headroom]

37 minutes ago, Graham47 said:

How then do you explain those ‘low mileage’ owners who haven’t had problems or those ‘higher mileage’ owners (mainly appear to be around 21-22 MY) who do ?

There are 67 pages in this thread i cannot remember many if any "low mileage" owners posting that they have had no issue, have you  any figures to back up your statement?

[Mooly]

2 hours ago, Max_Headroom said:

I thought there were many examples of this posted in the thread.

I can't recall seeing one. Current draw logged over a decent time period that the car is inactive is what is needed rather than just Battery voltage.  

[Graham47]

24 minutes ago, Max_Headroom said:

have you  any figures to back up your statement?

Yes… me.

We also have reports of dealers replacing batteries without much persuasion.  That tells me they know something.

[Mooly]

2 hours ago, Max_Headroom said:

If you drive an ICE car infrequently and do not do many miles when you do drive it  the battery will  eventually let you down,

That is a logical assumption but speaking from real experience it is not always so. My fathers old Corolla did as few as 500 miles a year for a couple of years and only a 1000 or so in other years from around 2014 to 2019. It stood outside on the drive and never suffered any Battery issues and in fact last had a Battery in 2012 due to suspicion of leakage. The car is 21 yr old next year.

2 hours ago, Max_Headroom said:

and from what i have read in the thread the Hybrid system doesn't charge it as fast as an alternator in an ICE car

I think you could be right on that and this is something that again would be easy for a proper investigative test.

Again we need to see current into the Battery when beginning charging from a known partially discharged battery state into an otherwise healthy (new) battery. An ICE with alternator can deliver upwards of 70 amps and more at little over idle speed and not much lower than that at idle. Remember it can cope with lights, heated window, wipers, blower etc at idle without the battery entering a discharge condition.

I remember reading decades ago that an alternator can never fully charge a battery and at the time I couldn't understand why. Surely it can. Only in later years have I come to realise what was probably meant by that blanket statement and it is that the alternator with its fixed 14 or 14.4v output will quickly bring a battery to a high state of charge but would then need to run for a very long time (perhaps 30 hours or more) to fully charge the battery and of course that never ever happens.

Does anyone know the current output capability of the DC/DC convertor used in the hybrids for charging the 12v battery and powering all the 12 volt equipment?

That is another missing piece of information to me.   

[Cyker]

You can't really compare newer cars to older ones - With older cars, when you turned them off, they were off.

With newer and newer cars, there is more and more standby current drawn to run the computers. The Keyless Entry system seems particularly thirsty, as disabling it seems to extend the standby time of the 12v Battery, and is something we've recommend people do if they're going to leave the car standing for long periods of time.

I suspect the always-connected internet that allows you to remotely power on e.g. the HVAC or see car stats also adds a considerable power draw.

[Mooly]

2 hours ago, Cyker said:

You can't really compare newer cars to older ones - With older cars, when you turned them off, they were off.

Well up to a point but the ECU, the immobiliser, the receiver for the locking and unlocking from the key and so on are all powered on a car like the old Corolla.

The secret is in micro power design and I think this is where the failings are. Manufacturers have just totally underestimated how lead acid Battery technology is unsuitable for this kind of application.

  

[Cyker]

One difference is the remote systems are passive listeners, which doesn't need much power, but the smart entry systems are active and continuously ping, which uses a lot more power.

But you're right about the power - The batteries are not scaling up with the increasing amount of electronic crap that gets loaded into modern cars.

It's kinda funny as the Battery in the Mk4 is literally the lowest tech type of lead acid Battery - Even my Mk2 had an EFB, and the older Mk3 Yaris hybrid had an AGM Battery!

The one in the Mk4 is just a normal flooded lead acid starter battery like we used to use in like, the 1980's!  

 

[Max_Headroom]

4 hours ago, Graham47 said:

We also have reports of dealers replacing batteries without much persuasion.  That tells me they know something.

Where are all these reports?

All that tells me  is Toyota are replace whatever parts need replacing under warranty as they are obliged to, i believe it has been said in the thread leaving the Battery low all the time will damage it therefore the people who dont drive often and are having these issues are having their damaged batteries replaced nothing more!

[Derek.w]

The problem with a voltage reading is if you just put a charge through the Battery then before taking a reading you need to turn on headlights for a couple of minutes or just leave it standing for at least a couple of hours before taking a reading.

Otherwise you get a false reading.

Yes some systems take a voltage reading when the Battery is under a TEST load for a more accurate reading ie. using a Battery load tester to determen the state/ability to hold its rated charge of a given type/ampage of battery.

[Graham47]

3 hours ago, Max_Headroom said:

Where are all these reports?

In the preceding 67 pages and also FB.

You must also have read reports of owners struggling to accept it’s a warranty claim and is down to low usage or have paid for their own replacements.  Other dealers have not.

[FROSTYBALLS]

3 hours ago, Max_Headroom said:

Toyota replace whatever parts need replacing under warranty as they are obliged to

Could argue that it isn't a warranty issue.

The warranty covers against manufacturing defects. For example, having a Battery go flat due to little use or whatever, which then damages the Battery so it won't hold charge, isn't necessarily a manufacturing defect.

[Max_Headroom]

9 hours ago, FROSTYBALLS said:

Could argue that it isn't a warranty issue.

The warranty covers against manufacturing defects. For example, having a battery go flat due to little use or whatever, which then damages the battery so it won't hold charge, isn't necessarily a manufacturing defect.

 The majority of  members here believe the 12v problem is due to lack of use many now have solar chargers, smart chargers and jump packs so they don't get caught out, others believe it's a faulty batch of Battery isssue if the latter is causing the problem it should be replaced under warranty. 

[Roy124]

Max, except the former will be able to get to the garage to get a new Battery under warranty. 

And also convince said garage that they have a maintenance kit as well.

[RickyC]

On 11/18/2023 at 10:01 AM, MCatPG said:

I expect this thread (Yaris Cross - consistently flat 12v battery) will be merged with the big 12V battery thread, where the following comment has been made by me and others many times, but just in case anyone reads about this issue here and doesn't find the big thread....

The number of miles you do each week or each year is irrelevant.

What matters is the number of hours each week during which the car is in READY mode and the shift is in DRIVE. During these hours the car can be stationery (with HOLD selected) or in motion, it makes no difference.

Here is the reason, for anyone is isn't up to speed on all this yet. The 12V battery is not charged in the conventional way by an alternator on the engine. It is charged using current from the high voltage traction battery, which in turn is charged by the engine, which will start and run if you are charging while the vehicle is stationary. But the on-board charging will only happen while the car is in READY + DRIVE. That's the way the system has been designed and you have to live with it.

Why are you sayng READY + DRIVE ?

DC - DC is charging the Battery also in READY + PARK.  

In DRIVE probably the DC-DC generates more current to support a bigger request from services but also in P the Battery is charged.

I don't think is safe to stay in READY + DRIVE with HOLD selected for a long time. 

HOLD should be used for short stops ( eg. Road Light ) but not for long ones ( witing in the car or a train crossing ).

[anchorman]

On 11/19/2023 at 12:01 PM, Max_Headroom said:

If you drive an ICE car infrequently and do not do many miles when you do drive it  the battery will  eventually let you down, the Hybrid 12v battery is much smaller than an ICE vehicles battery and from what i have read in the thread the Hybrid system doesn't charge it as fast as an alternator in an ICE car i dont believe its a *bad battery issue i believe owners having these issues simply dont drive them enough.

*obviously some cars will have duff batteries but that will be the minority.    

The statistics don’t add up.  I don’t just change batteries, I test them and they are cream crackered.  I’ve not come across one that can be recovered.  

[Rich L-T]

My 20 month old (with 9,000 miles) Yaris Cross has just refused to start again having been left for 4 days in my garage. This is the 3rd time it has done this. Toyota locally tell me this is a known problem with hybrids and the only solution is to up my annual mileage or put the car in R and let it charge itself up for an hour. The AA has told me the 12v Battery is only pulling 14amps and needs replacing. He says the problem is endemic across all Toyota hybrids. 

This is my 4th Toyota and first hybrid. The 3 petrol engine cars were totally reliable and never let me down. I can't even recall a component being replaced. I wish I had never bought the Cross. To be told I need to up mu mileage, buy a starter pack, or run the car in R for at least an hour per week is beyond belief.

 

[Cyker]

There have been cases of some dealers changing the 12v under warranty where they've felt they failed unreasonably prematurely, but it's not consistent - Some have been adamant it's not covered under warranty.

I do wonder if the charging profile is something that is contributing to the shorter life of the 12v batteries, as this problem seems to be much more prone on hybrids and EVs.

Could it be something like the high in-rush current from an alternator helps knock some of the scale off the lead plates, but the more constant and gentle charging of the DC-DC converters doesn't do this...?

Maybe if car manufacturers put some of the same Battery re-conditioning circuitry you get in the better trickle chargers it could help mitigate it...?

(Side note - I'm still not having any problems with mine, and I can jinx it as much as I want for the next 6 months as that's apparently how long the charge in the Noco jump starter in the car will last when I forget to charge it  )

[TonyHSD]

Hi, 

not a real issue with the car but more with the seller who should have been clear , small 12v batteries need regular maintenance or risk been depleted. Instead, dealers are offering unnecessary accessories like dash cams etc which only adds to the existing Battery problem. 
Once the Battery been low enough not to start the car then after even if it was fully charged the damage was already done and this Battery will need replacement. There are also procedures for maintenance of these cars and batteries by dealers and while in transit which likely been neglected here in uk as so,d other things prior to new car delivery., tyre pressures for example. 
The best way now is to argue and request a new battery replacement under warranty with pretext of premature failure and not fit for purpose. Then invest in a smart charger and if the car not in regular daily use of 30 min or more each time you start it recharge the battery via smart charger once every few weeks, winter times more often or use the car in ready mode for 30-60 min once a week. Don’t let your new battery gets too low. 
There  are some other settings you can do to help extend battery life, for example turn off home lights function, auto fold side mirrors, auto parking brake engagement,  disable connected services if you don’t use them, anything really that can drain your battery unnecessarily. 
Good luck 

[Cyker]

You could also get the Yuasa Battery for that car - It'll be better quality and have a higher capacity than the weird turkish one that is the current standard OE unit.

It does seem with the new Yarisususesieses, they need to be trickle-charged if not used frequently. I've not had any issues with mine but I drive it every day, sometimes not very far, but thanks to London traffic always very long  

[Max_Headroom]

2 hours ago, anchorman said:

The statistics don’t add up.  I don’t just change batteries, I test them and they are cream crackered.  I’ve not come across one that can be recovered.  

 

I am still convinced its lack of use causing the bad Battery problem not the Battery being bad in the first place (as it says below) This is due to the fact that the Battery will self-discharge if it isn't used regularly, and this can eventually lead to the battery being unable to hold a charge.

 

The most common complaint about the Toyota Hybrid 12v battery is its tendency to have a problem starting when left sitting in the garage for a long time or only driven on short trips often. This usually comes from people who just recently shifted to hybrid vehicle

Normally, the problem itself lies with the way the hybrid vehicle is used. The Toyota Hybrid 12v battery will likely develop problems starting when only driven on short trips or has been left in the garage for a while. This is due to the fact that the battery will self-discharge if it isn't used regularly, and this can eventually lead to the battery being unable to hold a charge.

Toyota Hybrid 12V Battery Problems - Why Do They Occur? (cararac.com)