12v battery maintenance, issues, etc.

[Stopeter44]

31 minutes ago, Bob66 said:

It's not all about money, Greta and I, are trying to save the planet too.  🙂

That's how we settled on the Yaris hybrid, it was the best way forward for us in 2021. Reduced CO2 emissions, and roughly 30% better fuel economy (maybe 35%, since I've slowed down to get the best out of the Gen IV hybrid system).

[Cyker]

Hey stopeter, can you find out the TSB of the DCM update? I thought only the RAV4 had a dodgy DCM that was draining the Battery and needed a firmware update, but if the Yaris has a similar problem maybe the 12 Battery isn't all to blame...?

A good result though - Kudos to your dealer for just sorting it out with no fuss! A lot of dealers could learn from that example. I'm especially impressed they even offered to change the Battery after so long!! That's been a lot less consistent here.

[RickyC]

15 hours ago, Stopeter44 said:

A good day today, because after Toyota assistance started the car, I took it directly to the dealer where they tested the battery and proceeded with the DCM update. After they had finished the DCM update, they came to me and said the 12v battery was shot, and it would be replaced under warranty with the new updated battery (45AH).

Do you know which Battery they have installed as replacement ?

[Stopeter44]

6 minutes ago, RickyC said:

Do you know which battery they have installed as replacement ?

No, but they assured me its was the same as the MY24 Yaris Battery.

[Roy124]

15 hours ago, Stopeter44 said:

better fuel economy (maybe 35%, since I've slowed down to get the best out of the Gen IV hybrid system).

Have you noticed it makes virtually no difference to journey times but induces less stress?

I am fortunate to have only one 'wall of death' and mostly travel on the old style A and B roads.  We do one regular 75 mile journey and not one dual carriageway and only one bypass.

[Stopeter44]

24 minutes ago, Roy124 said:

I am fortunate to have only one 'wall of death'

The only thing I think of from that is a very tight banked hairpin bend ?

[Countryside]

1 hour ago, Stopeter44 said:

No, but they assured me its was the same as the MY24 Yaris battery.

That’s tells me it’s an improved battery 

[dcweather]

After my wife's failed after 7 years I got one of these:

https://commercialvehiclelights.com/product/ring-battery-power-bank-jump-starter-booster-6000mah-compact-lithium-rppl200/

There are two special terminals for it under the bonnet and it works great. Keeps in glove compartment because Battery failed once in Tesco car park. won't work if Battery plates have failed and shoted. Great to get you home and you can charge your phone from it as well.

[Roy124]

1 hour ago, Stopeter44 said:

The only thing I think of from that is a very tight banked hairpin bend ?

No, a solid wall of trucks, often in both lanes and frequent closures from collisions.  Friday evening rush northbound (from about 3pm Thursday) and Monday morning southbound are the worst.

[Cyker]

Ahh sounds like my part of the M25 on a holiday weekend!  

[MCatPG]

The idea that a 12V auxiliary Battery with a higher Amp/hour capacity will solve completely the problem of discharged batteries seems to be popular, but it is wrong.

The problem can be analysed as 5 factors:

1. The auxiliary Battery sustains a continuous discharge because of passive or "parasitic" currents - which I call static discharge. All modern cars are like this, you can't isolate the Battery by turning off the ignition switch.
2. The auxiliary battery is charged only when the car is in Drive mode.
3. There is no way the driver can monitor or control the battery's State of Charge. We can provide our own means by using voltmeters and separate chargers but Toyota don't. (Do other manufacturers do this?)
4. Also, Toyota's Battery Management System for the auxiliary battery does not provide any warning that the battery is approaching a critical SoC, and it does not automatically shut down the static discharges and isolate the battery before it is damaged.
5. If it is discharged below a critical level and remains below that level for any appreciable length of time it will be damaged and will no longer have the same capacity. If the damage is sufficiently severe the battery will not hold any useful charge at all.

Replacing the battery with one which has a higher Amp/hour capacity or a better build quality will help if the periods of static discharge are not too long and the periods in Drive mode are long enough, but if not then even a high quality battery with a higher capacity will be damaged.

I continue to see the problem discussed in this thread as primarily a failure of systems design, aggravated by the installation of inadequate and poor quality batteries in some markets. Replacing the rubbish 12V batteries will mitigate but won't solve the problem.

Toyota, and possibly most other car manufacturers, need to redesign their auxiliary Battery Management Systems to provide something like a 12 hour early warning to drivers that a charge is needed and then, if no action is taken, to isolate the auxiliary battery before it is damaged.

[hind]

22 minutes ago, MCatPG said:

The auxiliary battery is charged only when the car is in Drive mode.

*in Ready mode

22 minutes ago, MCatPG said:

Replacing the battery with one which has a higher Amp/hour capacity or a better build quality will help if the periods of static discharge are not too long and the periods in Drive mode are long enough, but if not then even a high quality battery with a higher capacity will be damaged.

You are not taking charging speed into consideration which relies on the voltage. That means, charging the Battery from 20% to 80% takes less time than charging Battery from 40% to 100%, despite the thereotical same Ah pumped into. That is because the current is getting lower when you approach max voltage, limiting the charging speed.

That is why having larger capacity helps. Even with the same trip duration, possibility to charge the 12V Battery with a higher current allows to regain more energy during the short trip. Of course it won't help if you have negative energy balance which happens with the regular ICE engines doing short hops but as I calculated that according to power consumption logs, it only takes around 2 minutes of Ready state to recharge the whole system startup up to engaging the DC/DC converter which starts the charging process. So any longer than 2 minutes trip should add to the overall charge level.

[Chas G]

I was looking at lots of posts on the Ford Puma forum regarding 12 volt Battery problems........er not that I am thinking of trading in my Yaris Cross. Purely academic interest.

People seem to be blaming the "Wombat" 12 volt Battery fitted to their Pumas.

I am tempted to post on their forum suggesting we swop our Mutleys for their Wombats and see how we get on.

If the problems persist then it points to the 12 volt charging managent system being defficient.

 

[Cyker]

Another factor not accounted for above is the battery's resistance to degradation.

There are, broadly, two types of lead acid Battery - Starter type, and deep-cycle type.

The starter type are designed to supply lots and lots of current very quickly, and have lots of thin lead plates full of holes for maximum contact surface with the acid. However, they have to be kept at near-100% charge all the time, as the lead plates are very fragile and the lower the charge and the longer they're kept at that sub-100% charge, the faster they degrade.

The deep-cycle type is designed to be cycled up and down repeatedly and just have big thick plates which allows them to resist degradation. It can't deliver as much current, but doesn't mind being used to run things for long periods before being charged up.

A lot of better quality car batteries, esp. ones rated for stop-start, have a bit of a mix of the two, so they can provide enough current to start the car repeatedly, but also withstand being at lower states of charge for longer without significant degradation.

It seems the mutley Battery is not one of those

However, the Yuasa more likely is, since it seems to have done a lot better and they even advertise its lower rate of degradation as part of its features.

[MCatPG]

On 2/28/2024 at 10:26 AM, hind said:

*in Ready mode

Correct.

On 2/28/2024 at 10:26 AM, hind said:

That is why having larger capacity helps. 

Yes it helps but it does not solve the problem. It's still possible to wreck a Battery with higher capacity if the use profile of the car exceeds the battery's capabilities. After the bigger/better Battery is wrecked the owner is still in the same position.

15 hours ago, Cyker said:

A lot of better quality car batteries, esp. ones rated for stop-start, have a bit of a mix of the two, so they can provide enough current to start the car repeatedly, but also withstand being at lower states of charge for longer without significant degradation.

Agreed. The typical stop-start Battery is an AGM which means the lead plates are separated by fibreglass matting which holds the electrolyte. It's what I have on my boat, 5 of these. They are very good batteries but I can still wreck them if I discharge them below 50% SoC which is why I have a device to alert me by SMS if shore power is disconnected, and an IP camera (which I check every day) pointing at the distribution panel to show me the discharge rate and SoC. Most other lead chemistry batteries use electrolyte  which is more-or-less motile, either fluid or gel. The Yuasa battery which has been mentioned here is the latter kind. From their technical specs they call it an SMF battery, which stands for Sealed Maintenance Free and tells you almost nothing about the architecture. They don't use the term AGM anywhere and I'm sure they would if that's what the battery is. So it's a "bigger" battery (more Ah), and probably better quality, but I think my point stands. It doesn't matter how big or how good the auxiliary battery is because the uncontrollable static discharge will eventually overcome any battery and the BMS won't isolate the battery before it is irrevocably damaged. It's a system design problem, not a battery specification problem.

[Mojo1010]

Think we can all agree even with a bigger and better quality Battery it still can fail if it isn't maintained. Having the extra few days buffer can be the difference, as someone could then use the car for a few hours and should be ok again. 

Owners forums like this are a great resource of information, can make a novice like me along with a certain chap who now has a charging fortress of a garage, into forum experts overnight 😂

[SPR]

This forum is literally an extended Toyota development team...hope they follow through 🧐

[hind]

3 hours ago, MCatPG said:

the BMS won't isolate the battery before it is irrevocably damaged

I don't think there is any stock-configured car that does that. Mainly because this would add to the overall power consumption + additionally complicate the system (you don't want to cut off the power from external systems if the vehicle is moving). If anywhere, I'd expect to see something like this with the aux Battery in campervans. 

3 hours ago, MCatPG said:

It's still possible to wreck a battery with higher capacity if the use profile of the car exceeds the battery's capabilities

Yet with the bigger capacity is less likely, considering there are two "dangerous" scenarios which increase the chance of the fault:

a) traveling often but very short distances (or more specifically, driving it for short periods)

b) leaving the car for prolonged periods without driving at all

+ of course combination of these two together

Bigger Battery increases your success rate in both scenarios. In first, you will recharge the Battery with higher current (of course to some extent, limited by the DC/DC and it's programmed max values). In second one, you will still be able to start the car, as Mojo said, by having a few days more until the voltage drops to a point where it won't be able to engage the Ready state anymore. 

 

 

[Dala]

A leadbattery should never be fully discharged !
Lead-acid batteries can only be discharged up to 50% before irreversible damage occurs (12,06V)

In practice, this means that you will only be able to use half of the Battery capacity, so the Battery will be OK.

At 12.0V or below volts your Battery is considered to be fully discharged or 'flat' and should be recharged as soon as possible. The lifespan of your battery will be severely affected if it remains within this voltage range for extended periods of time.

So to summarize:
Yaris hybrid can start even at low voltage (I tested 11.7V)
But nothing will change the fact that the car battery is already damaged forever and it is necessary to drive often or recharge it.

[RickyC]

22 hours ago, Cyker said:

Another factor not accounted for above is the battery's resistance to degradation.

There are, broadly, two types of lead acid battery - Starter type, and deep-cycle type.

Probably for which the 12V Battery is used on Toyota Hybrid cars, the better kind of Battery shold be the one used on UPS systems, that are designed to supply a reduced current for a long time. 

I wonder why Toyota is using a different kind of Battery.

Moreover I'm curious to see which battery is installed on JP made Yaris ( e.g the ones sold in Australia )

[hind]

1 hour ago, RickyC said:

Moreover I'm curious to see which battery is installed on JP made Yaris ( e.g the ones sold in Australia )

35Ah Yuasa

Source: https://www.youtube.com/watch?v=ZR1nsxCzwy0 

 

[Dexter290]

On 2/27/2024 at 10:54 AM, Stopeter44 said:

The only thing I think of from that is a very tight banked hairpin bend ?

Only one? I've got 5 between here and the village.

[Countryside]

Last Sunday I did 100 miles on motorway Monday and Tuesday didn’t use the car Wednesday I did 20 miles Thursday didn’t use the car today Friday not use car rain again ! Tomorrow Saturday doing 20 miles Sunday doing 20 miles ! My question is in this week would the Battery go dead with not in use 4 days ? Many thanks for your help

[Jasper.]

Even with the Mutlu in mine it wouldn't go flat with that kind of use. Now I have fitted the Yuasa I'm really hoping it's the end of any issues.....

[jthspace]

2 hours ago, Countryside said:

Last Sunday I did 100 miles on motorway Monday and Tuesday didn’t use the car Wednesday I did 20 miles Thursday didn’t use the car today Friday not use car rain again ! Tomorrow Saturday doing 20 miles Sunday doing 20 miles ! My question is in this week would the battery go dead with not in use 4 days ? Many thanks for your help

Assuming Battery is healthy, then "no".