12v battery maintenance, issues, etc.

[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)

 

[Max_Headroom]

2 hours ago, Rich L-T said:

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.

68 pages here - https://www.toyotaownersclub.com/forums/topic/197814-12v-battery-maintenance-issues-etc/?do=getLastComment

[Gray86]

Now it has gone flat, it will have lost some capacity. A CTEK MXS 5.0 charger will keep it conditioned, seeing as you have a garage, this may be an option? 
 

My dad leaves his CHR in airport car parks for 2 weeks over winter with no issues, as he tops up the 12v Battery with the charger beforehand. 

[Derek.w]

Just charged my 12 volt Battery today it was standing at 12.28volts so just below 50% so plenty of power to start car but batterys loose its ability to hold a charge below 12.20 volts so I dont let it drop into that area.

CTEC charger was showing 3 leds lights on out of 7 leds led 6 is fully charged/float mode. 

[Cyker]

Out of curiosity, what sort of overnight temperatures are you seeing?

[FROSTYBALLS]

Similar topics merged.

[jthspace]

19 hours ago, RickyC said:

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 ).

If I stay in HOLD too long (4 way temp traffic lights the other day) HOLD disengaged and the hand brake (what's it called now? Finger brake??) came on instead.

It was only a few weeks after I got the car that I realised that HOLD also kept the brake lights on, I thought I was using HOLD to avoid foot brake blindness to drivers behind me. I now flip the brake button.  

[Max_Headroom]

So is the recommended method - 

Put the car in READY mode in neutral PARK with the handbrake on?

[Stopeter44]

7 minutes ago, Max_Headroom said:

So is the recommended method - 

Put the car in READY mode in neutral with the handbrake on?

Not a good idea, the Neutral position is of no use in a hybrid, the hybrid system is disconnected. As for tail lights staying on, don't worry about it, only old farts (I'm including myself here) seem to worry about it.

[TonyHSD]

Ready mode in P only. Parking brake on for safety. Electronic accessories can be on or off this is not an issue, as long as the car is in P and ready mode the hybrid system will charge the 12 v Battery. 
 

[Max_Headroom]

26 minutes ago, Stopeter44 said:

Not a good idea, the Neutral position is of no use in a hybrid, the hybrid system is disconnected. As for tail lights staying on, don't worry about it, only old farts (I'm including myself here) seem to worry about it.

DOH i meant PARK not Neutral.

(original post edited)

Why do they have neutral if its of no use?

 

[hind]

You can use it to disconnect wheels from the gearbox and allows you to push/tow the car a little in case of a failure.

[Cyker]

Alas it doesn't do that - Even in N, all the gears and engine are still interconnected; There is no gearbox or clutch that can disengage the drivetrain from the wheels due to the way the HSD is designed.

The N mode is purely logical, i.e. the computer just cuts power to it and doesn't let it flow in or out of the various motors in order to 'fake' a mechanical Neutral.

It's kinda pointless, as unlike a real Neutral, it's still unsafe to tow a hybrid in N for anything but a short period of time, and if there was a computer malfunction the N could easily become not-N.

The subject of why it's even there pops up every now and then on here, and there was some debate about this back in the day on here; I suspected it was for legal reasons, i.e. countries requiring cars to have a Neutral to be homologated, even if it didn't actually do anything (A bit like that thing of how you have to carry spare bulbs in france, even if they're not for your car, to avoid getting fines from the gendarme  )

 

As an aside, the BRAKE HOLD and Electronic Parking Brake (EPB) are absolutely not the same thing:

The Brake Hold is basically a 'virtual foot', that holds down the brake pedal for you, and has all the same effects as if you were holding down the brake pedal (All 4 wheel brake calipers are engaged using hydraulic pressure, all 3 brake lights are lit).

The EPB is analogous to a handbrake (Only worse) and only brakes the rear wheels, with a pair of electric motor-driven screw clamps.

The car seems to have been programmed with the "If a Pause turns to a wait, use the handbrake!" rule, as it will automatically disengage the Brake Hold after a few minutes and engage the EPB - You will feel the whole car lurch when this happens, as the front wheels start pulling against the rear brakes. You can override this before it switches over by tapping the brake pedal, which will restart the timer, but it's probably best not to sit on the Brake Hold for hours  

I tend to use the Brake Hold for the above reason, as the car will stop wasting energy trying to drive against the brakes after a few moments, but on the EPB it will constantly send energy to MG2 to try and drive forwards. Also, the EPB is much slower than the Brake Hold to disengage, which slows down my 0-30 times at traffic lights, and that's no good is it??   

Personally, I think the best practice is to use Brake Hold for short stops, e.g. at the lights, and just put it in P for longer ones, with the EPB automatically engaging so the front and rear wheels are locked (Front by the P-mode parking pawl, and the rear from the EPB).

 

[MCatPG]

On 11/20/2023 at 3:36 PM, RickyC said:

Why are you sayng READY + DRIVE ?

I read somewhere that this is the correct setup for static charging of the 12Vbattery, but I don't know where. I think I was wrong about that. Can't edit the post.

There is a safety issue here so I put a bit of effort into trying to find the right answer.

The car's manual says nothing about this (I searched the electronic copy using several terms). Useless.

Toyota's article about maintenance during the godawful Lockdowns says use P.

The internal instruction document which Toyota issue to their dealers about PDI work for the Battery systems says use P.

[G L J]

Had my Battery changed at my local tyre depot yesterday due to the Battery losing charge and the car not starting after three days of not being used.

I have suspected it is not holding its charge properly for a long time but decided to change it before the really cold winter months.

Do not mind connecting booster pack to fuse box in summer but do not fancy doing it on a cold wet January morning at 6.30am.

The original Battery was tested and failed .

They have fitted a Varta Blue Dynamic rated at 44ah so hopefully all should be well now.

 

 

[Roy124]

Gwynfor, I know what you mean about the fuse box connection.  Where the Battery is inaccessible I got the garage to fit a charging tail to the Battery.

Note to self:

Think about a connection for the booster pack too as the fuse box could be inaccessible with the car in the garage.

[Derek.w]

Yaris Hybrid have two jump start connectots one under the bonnet in a fuse box.

Second one is bolted onto the Battery terminal post its just about half way down on the right red lump of plastic sorry its not a good picture.

[Roy124]

57 minutes ago, Derek.w said:

Second one is bolted onto the battery terminal post its just about half way down on the right red lump of plastic sorry its not a good picture.

Which is where you might secure a permanent charging tail.   It's not somewhere you would want to use in emergency.