12v battery maintenance, issues, etc.

[Graham47]

9 hours ago, TopGeek said:

Leaving the car in 'Ready mode' for an hour may offset the risk to a degree but it will not charge the battery to full capacity.

@TopGeekDo you have evidence to back this up ?
What is the charging rate of the dc-dc converter ?

[CruxisCore]

By the graphs it seems that when it's actually doing the most it can, we're looking at like 14,3-14,5v when charging and then theres the seperate lower smart charging thing that pushes like 12,7-13,5v. So probably pretty usual cycle of charging hard and then just more of a maintenance trickle charge

I dont think there is any reason to believe actually driving does anything more. Since regardless the power comes from the hybrid Battery and when that gets low, the ICE starts up to charge the hybrid Battery. There's a reason why alternators charge way more when driving, but none of that applies to how these hybrids charge. Of course, in a whole lot of cases short trips usually equal in short time in Ready-mode, while long trips equal more time in Ready-mode. Exceptions ofc exists in like heavy traffic, where distance may be short but you are still stuck in Ready-mode for a long time.

EDIT: That said, I guess it's possible that it will only go to the "smart charge" state when stationary in Ready-mode and push that +14v when theres more excess power coming into hybrid Battery. Cos surely driving around due to regenerative braking gets more energy and more efficiently than just running the ICE. However with a quick googling I already found that at least with RAVs it will push 14+ volts even when stationary in ready modes, so its not exactly that either.

The user @Dala has a lot of good graphs about this in his post history, check them out: Dala's Content - Toyota Owners Club - Toyota Forum

[TopGeek]

9 hours ago, CPN said:

That's fine, however, many of us have found that most of our cars do not have AGM batteries.

Then you don't need to use the AGM option that is available on most smart chargers.

[TopGeek]

5 hours ago, Stopeter44 said:

So Nico GB40, or equivalent, is fine ?

Logically yes. That unit is capable of delivering 1000 amps, whereas the current draw needed the raise the voltage sufficiently to enter 'Ready' mode would be unlikely to exceed 5 amps.

[TopGeek]

2 hours ago, Graham47 said:

@TopGeekDo you have evidence to back this up ?
What is the charging rate of the dc-dc converter ?

Not specifically but charging logic tells me that it is not possible to fully charge the Battery within an hour, during which the ICE will start and stop several times. All that can possibly achieve is to charge the Battery enough to offset the 'no start' situation.

[RickyC]

Sorry Brian, why are you correlating the 12v Battery change logic with ICE start and stop ?

[TopGeek]

4 minutes ago, RickyC said:

Sorry Brian, why are you correlating the 12v battery change logic with ICE start and stop ?

Not sure that I understand the question. Leaving the car standing in 'Ready' mode allows the ICE to charge the hybrid Battery, which then charges the 12-volt Battery. It is essenntially the state of charge of the 12-volt Battery that dtermines access to 'Ready' mode. It's all interrelated.

[RickyC]

I agree but I think that the charging process is totally idependent by how many time the ICE stays on or off.  I expect that an hour trip or an hour stand in Ready mode is quite equivalent for 12V Battery charge.  Probably one hour standby could be a little more efficiente because during drive you use more 12V powered components so part of the DC-DC generated power is immediately used and not sent to Battery, but I don't see any correlation between the ICE usage and Battery charge.

[FROSTYBALLS]

On 7/10/2023 at 11:50 AM, chazbri said:

Has anyone been given this advice from a Toyota dealership to leave the car in ready mode for an hour each week when it's not being used much?

Toyota GB issued this advice in April 2020, and has been posted on Toyota Owners Club since then - see:

 

[Roy124]

50 minutes ago, RickyC said:

  Probably one hour standby could be a little more efficiente because during drive you use more 12V powered components so part of the DC-DC generated power is immediately used and not sent to battery

Not strictly true.   You would need to shut off aircon, media, unnecessary lighting.  It would be truer in bad weather when other services such as seat heating, window heating, wipers, headlights etc might also be on.

[Graham47]

2 hours ago, TopGeek said:

All that can possibly achieve is to charge the battery enough to offset the 'no start' situation

Even if true, that’s all that is necessary.

[RickyC]

1 hour ago, Roy124 said:

Not strictly true.   You would need to shut off aircon, media, unnecessary lighting.  It would be truer in bad weather when other services such as seat heating, window heating, wipers, headlights etc might also be on.

Obviously if you leave the car in standby in Ready mode with the goal of charging 12V Battery you should do the best to reduce 12V consumption, shutting down aircon and media.  Probably, if you need to stay in car for one hour waiting for someone, you'll sin 😀 starting aircon and multimedia.

In any case also in good weather condtions the chance to use more 12V powered services is higher during drive ( at least DRL will be on )

[CPN]

3 hours ago, TopGeek said:

Then you don't need to use the AGM option that is available on most smart chargers.

I already know that. I was merely pointing out the fact...

[CPN]

3 hours ago, TopGeek said:

Not sure that I understand the question. Leaving the car standing in 'Ready' mode allows the ICE to charge the hybrid battery, which then charges the 12-volt battery. It is essentially the state of charge of the 12-volt battery that determines access to 'Ready' mode. It's all interrelated.

I don't think that is correct. You are making it sound like the 12v charging is dependent on the ICE running or not. Once in "Ready" mode, the 12v charging is determined by the DC-DC Convertor powered by the hybrid Battery whether the ICE is running or not and that charging will be constant all the time the car is in "Ready" mode.

The primary purpose of the 12v Battery is to control the safety contactors that bring the hybrid (traction) Battery online for the car to use. All of the car's 12v requirements will ultimately be controlled and sourced by the relevant ECU in tandem with the DC to DC converter.

The "decision" to startup the ICE is determined by the SoC of the hybrid battery or more motive power required via the power split device or both simultaneously. Nothing to do with the charging of the 12v auxiliary battery.

[CPN]

Further to my last: I guess what I am trying to explain (perhaps badly) is that while the car is running and in "Ready" mode, all of the cars 12v requirements will be provided by the traction Battery via the DC to DC converter. In our Toyota hybrid powered cars, the 12v auxiliary Battery is truly that. Auxiliary and not primary. (source of 12v)

Of course, it goes without saying that when the car is "off", this same auxiliary Battery keeps other systems "ticking over" like the smart entry/exit system, alarm etc and other 12v powered systems that you choose to switch on without the car being in "Ready" mode.

[TopGeek]

30 minutes ago, CPN said:

I don't think that is correct. You are making it sound like the 12v charging is dependent on the ICE running or not. Once in "Ready" mode, the 12v charging is determined by the DC-DC Convertor powered by the hybrid battery whether the ICE is running or not and that charging will be constant all the time the car is in "Ready" mode.

The primary purpose of the 12v battery is to control the safety contactors that bring the hybrid (traction) battery online for the car to use. All of the car's 12v requirements will ultimately be controlled and sourced by the relevant ECU in tandem with the DC to DC converter.

The "decision" to startup the ICE is determined by the SoC of the hybrid battery or more motive power required via the power split device or both simultaneously. Nothing to do with the charging of the 12v auxiliary battery.

Thanks for that detailed explanation. Even so, I stand by my assertion that one hour idling in 'Ready' mode is not enough to fully charge the AGM Battery. for those who only use their car irregularly and/or for short distances, the SoC of the AGM Battery will tend to fall rellatively rapidly in normal use.

[CPN]

6 minutes ago, TopGeek said:

Thanks for that detailed explanation. Even so, I stand by my assertion that one hour idling in 'Ready' mode is not enough to fully charge the AGM battery. for those who only use their car irregularly and/or for short distances, the SoC of the AGM battery will tend to fall relatively rapidly in normal use.

In the case of an AGM Battery, I would probably agree with your assertion. However, by research on here, it would appear that the majority of Yaris Hybrids do not have AGM batteries just normal smaller capacity sealed ones.

[TopGeek]

10 minutes ago, CPN said:

In the case of an AGM battery, I would probably agree with your assertion. However, by research on here, it would appear that the majority of Yaris Hybrids do not have AGM batteries just normal smaller capacity ones.

Yes, the AGM style is a relatively recent innovation. I don't know exactly when Toyota started using them on the Yaris series (perhaps only since the Yaris Cross) but they seem to have caused a lot of controversy due to the relatively frequent 'no-start' problems. I only took delivery of my car on 1st March and have already had to call the emergency breakdown service twice. The technician told me he has several such calls every day and mostly for vehicles with AGM batteries, although I'm sure it happens with conventional batteries too. I have now bought a jumper pack and a smart charger.

[Max_Headroom]

42 minutes ago, TopGeek said:

I have now bought a jumper pack and a smart charger.

Could I ask how often  you drive the car?

[Cyker]

If you mean charging the Battery up from empty, you're probably right that an hour wouldn't be enough, but to offset the loss from the car being unused for a week or so it should be more than enough.

Whether it's AGM or not is not really relevant - They're all lead acid batteries at the end of the day and all act like lead acid batteries.

I think one of the issues is lead acid batteries degrade faster the lower their level of charge - Unlike, e.g. lithium cells, lead acid should be kept as close to 100% charged as possible, as long as possible, for maximum shelf-life. With cars that are sat unused for long periods, the Battery will experience these lower states of charge more often, accelerating wear. With normal starter batteries, the general wisdom is below 50% charge they degrade very quickly, which is why I hoped the ones they used in hybrids were using deep-cycle batteries, but as far as I can tell they aren't... (NB: AGM doesn't automatically mean deep-cycle! These are two different and unrelated qualities!)

 

[Cyker]

2 hours ago, CPN said:

In the case of an AGM battery, I would probably agree with your assertion. However, by research on here, it would appear that the majority of Yaris Hybrids do not have AGM batteries just normal smaller capacity sealed ones.

It seems the Mk3 and other hybrids of that era had AGMs fitted as standard, which I assumed was for safety reasons, but I guess they now consider flooded sealed batteries safe enough (As anchs says in another thread, if the accident is bad enough for it to be an issue you've probably got more pressing matters to worry about!!).

It's only really since the new generation they've switched to more 'normal' batteries - e.g. in the Mk4 Yaris and Mk 12 Corolla, which caught a lot of us out thinking they still had AGM!!

[TopGeek]

2 hours ago, Max_Headroom said:

Could I ask how often  you drive the car?

2-3 times per week and mostly only locally. The car has done 800 kms in 5 months..I'm disappointed the dealer didn't advise me the car was more suited to daily use and/or longer journeys.

[Max_Headroom]

1 hour ago, TopGeek said:

The car has done 800 kms in 5 months.

Roughly 100 miles a month i guess that's the reason you are having problems, as you say it stinks that the sales men/women dont ask what mileage you do as they must be aware by now there is an issue if you dont use it regulariy. 

[Max_Headroom]

13 minutes ago, Max_Headroom said:

it stinks that the sales men/women dont ask what mileage you do as they must be aware by now there is an issue if you dont use it regulariy. 

Its about time Toyota started being honest with their customers if this carries on they may well lose many.

 

Battery Fails to Start the Car

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 vehicles.

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.

Unlike plug-in hybrid electric vehicles (PHEV) or electric vehicles (EV), the Toyota hybrids currently in circulation do not charge with an extension cord. Like cars possessing internal combustion engines (ICE), the 12v battery of the Toyota hybrids needs the fuel-fed engine to run for some time to be energized.

In Toyota hybrid vehicles, the petrol-fed engine charges the high-voltage battery pack called the "traction battery" which then energizes the 12v battery via a DC-to-DC converter. This allows the battery to power the electric motor when needed, providing a boost of power and improving fuel efficiency. The hybrid system also recaptures energy that would otherwise be lost during braking and deceleration, using it to recharge the battery. This improves overall fuel economy by up to 40% according to the automaker.

The petrol engine in a Toyota hybrid vehicle is smaller and more efficient than a traditional petrol engine. It runs at a higher speed and produces less emissions. When the vehicle is running on battery power alone, it produces zero emissions. The petrol engine majorly comes into play when additional power is needed, such as for acceleration or climbing hills.

The petrol engine and electric motor work together to provide power, with the engine charging the battery when needed. This results in more efficient use of fuel, as well as reduced emissions. The Toyota hybrid system is a great example of how technology can be used to improve both performance and environmental friendliness.

The best way to avoid this particular problem is to make sure that you drive your hybrid car on long trips whenever you can. If you don't have time for that, take it on a stroll within your community or take that chance to go on a grocery run while you're at it for at least 15 to 20 minutes' drive daily just to keep its battery charged.

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

 

[FROSTYBALLS]

As has been said several times in the past, 12v Battery issues don't just affect Toyota hybrids.

Extract from a letter in the July/August issue of Boundless magazine:

"Since buying a new-style Honda HR-V 1.5 eHEV in April 2022, I've experienced a flat Battery on at least six occasions, either after leaving the car in the garage for a week or after lots of 'local' runs.

On the two occasions I've had to call roadside recovery services, the engineers have said they're frequently called out to hybrids and full EVs with flat batteries ...... ".

So it is an issue that is widespread across a number of manufacturers.