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12v battery maintenance


FROSTYBALLS
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It's never left plugged in whilst driving and that would be redundant anyway so there would be no point. Besides, I need the port for my OBDLink LX so that I can make use of Hybrid Assistant whilst driving (which is more useful).

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  • 2 weeks later...

My 2021 Yaris had its fourth jump start today in 1 and a half years. Last drive was 5 days ago and did 35 miles. Today no start and Battery reading was 4 volts. Useless, unreliable, £22,000 Toyota Hybrid embarrassment. Toyota's slogan for the new Yaris Hybrid was 'Why Stop?' .... that's if you can get it going in the first place. Would I buy another?..... NO!... If you don't use your car that much don't buy a 'small 12V battery' Toyota Hybrid. How pensioners would cope with this car I don't know.

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59 minutes ago, TruBlu said:

If you don't use your car that much don't buy a 'small 12V battery' Toyota Hybrid. How pensioners would cope with this car I don't know.

If this is such a big problem why haven't they replaced the Battery with a bigger one that will hold a charge longer?

Is there a reason why the car cannot start using the bigger Battery? (Not a hybrid driver just interested)

 

 

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TruBlu, it is a common hybrid issue.  I am a pensioner, I cope.  The problem is for people that don't visit forums such as these or who do not get good advice from their garage. 

The Toyota advice is put the car in Ready mode for an hour a week.  There is other good advice here. 

A different solution is possible with other makes with Kia enabling start using the big Battery

Max, a larger Battery weights more.  My garage fitted one 20% larger and it still went flat. 

The best fix is like Kia which enables a charge from the hybrid Battery but that is not an option from Toyota. 

 

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9 minutes ago, Roy124 said:

Max, a larger battery weights more.  My garage fitted one 20% larger and it still went flat. 

The best fix is like Kia which enables a charge from the hybrid battery but that is not an option from Toyota. 

Thanks.

They missed a trick there.

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I think partly the problem is the hybrids use a DC-DC converter to charge the 12v Battery from the big traction Battery, but it charges at a lower current than the maximum you can get from an alternator, so if you drive the car for short periods it never has a chance to put enough charge into the Battery - In that case even a bigger battery wouldn't help.

In normal cars, the alternator can put a much higher load on the engine when the 12v battery is low to charge it faster, but the hybrids seem to have a lower current ceiling.

I've never had an issue but I'm driving most of the day - The car is super efficient so maybe go on a long pleasure drive on the weekend... it won't hurt the wallet anywhere near as much as other cars and it's more fun than watching TV :naughty: 

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I think the hybrid Battery is a number of small cells arranged in series. A smaller number could be connected to provide a 12v source that could activate the system. 

It maybe the way Kia manage the system. 

I don't know if Tesla uses a 2 Battery system or just one. 

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Apologies been following this endless thread for quite some time. just an FYI I'm a daily user for my yaris hybrid - eventually I've grown dubious of the AGM (12V) Battery (but had more than one incident where my kids left stuff turned on in the car - I've installed a roof mount dvd player) - in which case I always jump started it with an other (lying around) 12V lead-acid Battery in parallel. 

My point (hopefully worthy) for sharing here is that you don't need to replace AGM with AGM which costs three times as much - yes they're tentatively taking longer to discharge etc - so to less frequent drivers it might tip the scale. Just for you to know I didn't "risk" it on own initiative, I called up local toyota dealership and the guy suggested so..and I've gone ahead with it and haven't regret it - it's now been close to a yr - for anyone still in doubt.

 

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3 hours ago, funky2nite said:

My point (hopefully worthy) for sharing here is that you don't need to replace AGM with AGM which costs three times as much - yes they're tentatively taking longer to discharge etc - so to less frequent drivers it might tip the scale. Just for you to know I didn't "risk" it on own initiative, I called up local toyota dealership and the guy suggested so..and I've gone ahead with it and haven't regret it - it's now been close to a yr - for anyone still in doubt.

 

Funky, you are quite right, any 12v Battery will work.  But ask yourself why Toyota goes to the additional cost of fitting an AGM Battery under a seat or in the boot when any cheaper wet Battery would do? 

Perceived wisdom on the forum is that a wet battery inside the passenger compartment would be a hazard in the event of a crash. 

 

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23 hours ago, Max_Headroom said:

How long does it take to recharge the battery from 25% by driving the car. 

As no one answered why not take the car for a short drive every 3 days if it goes flat after 5 or trade it for a non hybrid if you are doing so few miles. 

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For sure there are several workarounds. But, we're just trying to accommodate for something that clearly appears to be a design flaw.  

Leaving a car unused for up to one month, should not be a problem, providing you have a healthy Battery. We have done this multiple times, with Toyota hybrids too. 

Beyond this period, then yes, even older cars may have trouble getting going again, depending on weather. 

Two weeks is perfectly reasonable to expect without doing anything extra. It's a normal holiday away, or just a quiet time. I'd complain to Toyota and possibly swap the car for something else if your usage pattern repeatedly leaves a flat Battery. It's stress you could do without.

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On 9/23/2022 at 6:29 AM, Max_Headroom said:

How long does it take to recharge the battery from 25% by driving the car. 

Probably a lot longer than you think. If the Battery is 100% healthy and the voltage limited to around 14 volts (and it will be current limited as well) then I would estimate around 8 hours or more. As the charge increases the current falls away and so it takes a lot lot longer to put that last 10% back.

If the Battery is deteriorated then it will take longer still and you will have a lower overall capacity even when it appears fully charged.

On 9/22/2022 at 9:29 PM, Roy124 said:

I think the hybrid battery is a number of small cells arranged in series. A smaller number could be connected to provide a 12v source that could activate the system. 

A good idea in theory but may be problematic in practice. Draining some cells in a series chain makes managing and equalising charge on all the cells much more difficult. The cells in a high voltage Battery are also surprisingly small in capacity, only a few Ah, far far less than the cells in the 12v battery. 

It would also require that the hybrid battery is 'referenced' to ground (chassis, zero volts) which it may well be but isn't necessarily a requirement given the invertor technology.

The real answer to all these issues is better battery management and crucially better management of background consumers of power.

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2 hours ago, Mooly said:

Probably a lot longer than you think. If the battery is 100% healthy and the voltage limited to around 14 volts (and it will be current limited as well) then I would estimate around 8 hours or more. As the charge increases the current falls away and so it takes a lot lot longer to put that last 10% back.

Thats shocking they really do need to have a look at this problem if it becomes well known they are going to lose sales.

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Max, trouble is I think the volume of problems only occurred in 2020 with Covid lock down.  Their Ready Mode advice probably reduced many instances (complaints) and work around such as Battery packs and solar chargers reduced complaints even more. 

Now if the motoring press picked this up and caused widespread criticism of Toyota then maybe they would be moved to get out a fix. 

Just a thought, dies BZ4X have an auxiliary Battery

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1 hour ago, Roy124 said:

Max, trouble is I think the volume of problems only occurred in 2020 with Covid lock down.  Their Ready Mode advice probably reduced many instances (complaints) and work around such as battery packs and solar chargers reduced complaints even more. 

Now if the motoring press picked this up and caused widespread criticism of Toyota then maybe they would be moved to get out a fix. 

Just a thought, dies BZ4X have an auxiliary battery? 

What is “the volume of problems” ?
Is there any evidence (outside this forum) that there is a ‘significant’ problem ?
 

From time to time I look in on a Honda Jazz forum.  Not seeing any such issues with their new Hybrid model (and there are a number of ex-Toyota owners posting).

Similarly, nothing on HonestJohn.

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I've left my Mk4 for a bit over 2 weeks and it started no problems, so the problem isn't inherent to hybrids, but I use my one constantly during the week as part of my job (So much so that I have to service it roughly every 8-9 months to comply with the 1yr/10k mile requirement of the warranty! :crybaby:

I think the problem happens more if e.g. the Battery is old, and is especially likely to happen if the car isn't used much, and is then subsequently left for a long time.

That said Toyota should be aware of the problem as it's been a known issue for over 10 years - We had quite a few Auris hybrid owners complaining about it on these very forums back in the day - so it's a bit disappointing they still haven't come up with a solution.

I've suggested that they copy Hyundai's fix, which is quite clever - If the 12v depletes to a certain level, the car cuts off all 12v systems, and requires the owner to manually open the car, press a 12v Reset button, which then re-activates the Battery for a short time, enough for the owner to start the car. It stops the 12v depleting to the point where 'jump-starting' is required and I thought it quite a clever bodge in lieu of something better.

Some newer EVs can also automatically engage the traction batter contactors to charge the Battery, although in the case of hybrids that might not be so useful given how small the hybrid batteries are and how dangerous it is to discharge the hybrid battery!

 

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I mentioned this problem to my Toyota dealer when my car went in for its first service. Their reply was it was not required to check the Battery as they think the cause was that I had only done 2,500 miles in a year. If the problem existed after regular daily driving they would have looked in to it. Plus they said that my Battery would not be covered by the warranty as they blamed the issue on low mileage. In my opinion a low  Battery state after 5 days of not using the car is pretty poor for reliability. Plus when the battery is low the brake pedal pulsates and one headlight comes on and all the electrics go crazy with a clicking noise coming from somewhere. Four jump starts now in a year and a half.... not good is it on a brand new car? Never had this issue on any non-hybrid car (bring back the alternator I say) in the 41 years I've been driving. Everyone should mention this problem to Toyota having experienced the problem or not. BTW.... the solar trickle charger has not made much differnce unless used on a really sunny day.

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If you are doing such a low milage (2500 anually) the Battery is not getting a full charge as discussed earlier so when you park it you may only have 40%  charge a s you leave it 5 days with stuff running in the background it's not a wonder it goes flar, can I ask why you chose to pay so much for a car that does lots of MPG when you hardly drive it?

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