12v battery maintenance, issues, etc.

[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".  

[MCatPG]

23 hours ago, hind said:

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. 

Stock hybrid and BEV cars have a BMS which does the job for the Lithium traction Battery. At the very least there ought to be a warning system to alert the owner that the auxiliary Battery requires a charge.

22 hours ago, Dala said:

A lead battery should never be fully discharged !

Lead-acid batteries can only be discharged up to 50% before irreversible damage occurs (12,06V)

Agreed. Here is the SoC table for my Lifeline lead AGM batteries. Paying lots of money for good batteries doesn't alter the chemistry. The figures are for resting voltages, what you see if you isolate the Battery and leave it in a stable moderate ambient temperature for a while (published advice varies about the length of time). The moment the battery has any discharge or receives any charge the voltage will change. The moment the battery voltage drops below 50% irreversible damage occurs due to a phenomenon described as sulphation.

Lifeline Batteries State of Charge
Bold values from Lifeline manual, page 32. Other values are interpolated
100%				12.78			v		80%				12.54			v		60%				12.30			v
95%				12.72			v		75%				12.48			v		55%				12.24			v
90%				12.66			v		70%				12.42			v		50%				12.18			v
85%				12.60			v		65%				12.36			v		Never go below 50%

 

[chazbri]

Has any one any views on this ? If the Cross has been in ready mode for an hour each week as advised by Toyota to keep the Battery charged does an equivalent amount of travel time per week offer the same amount of recovery?

[Countryside]

Thankyou for replies I have a Chr at the moment but waiting to see the new 2024 Yaris excell in the showroom with the new revised dash big sat nav etc 

[hind]

29 minutes ago, MCatPG said:

Stock hybrid and BEV cars have a BMS which does the job for the Lithium traction battery.

And there is one in our HV Battery pack in Yaris as well 🙂 mainly because they do the hard work, are expensive to replace and it's easier for a single cell to go out of balance (because there are so many of them in a pack) when compared with regular 12V Battery. Li-ion's provide excellent performance but are much more fragile than the Lead-acid Battery. 

29 minutes ago, MCatPG said:

. At the very least there ought to be a warning system to alert the owner that the auxiliary battery requires a charge.

IIRC there is a message when the 12V battery drops too much. Somebody mentioned it somewhere in one of the threads. Of course you have to hit that sweet spot when the voltage is low enough to trigger the message and high enough to start the car 😉 

25 minutes ago, chazbri said:

If the Cross has been in ready mode for an hour each week as advised by Toyota to keep the battery charged does an equivalent amount of travel time per week offer the same amount of recovery

More or less but yes, you can assume that. 

[Tom Corbett]

Hi everybody.

This string has become very long so apologies for asking a question that may have already been answered. Our 2016 Yaris hybrid 12V Battery is loosing charge quickly. The AA home start guy says the Battery needs replacing. He doesn't carry suitable batteries and could not source one from the nearest Toyota dealer (Listers).

I have now booked up with Listers to get the Battery replaced. Here is the weird bit though. It will cost me  £171 to buy the battery and fit it myself. A simple job. But if I get Listers to fit it, it will only cost £140!! This just sounds daft but it is true. The downside is I have to wait 25 days to get the job done, and then I will have to drive the car 12 miles to the garage hoping I don't break down on the way. 

I will carry on looking through this string.

I have found out, thanks to this forum, how to charge the 12V battery up to get the Yaris started up. Key to Ready, depress footbrake, wait a minute, stick to drive. Has worked so far.

So whether or not I do the job myself for the extra £30 or wait 25 days is the decision I have to make, but my question here is :

1/ What is so special about the piddly little 35 AH battery that it can only be purchased from Toyota, and is relatively quite expensive?

2/ What on earth is the thinking behind charging a negative amount for labour!?

Thanks and again apologies if this has already been discussed somewhere.

I will carry on looking through this string.

 

 

[CPN]

A replacement Battery should only cost you at most ~£75 if you buy it and fit it yourself NOT from the dealer. Keep looking back through this thread and you will find the links...

[Graham47]

Special buy available in store from 10th March ….
https://www.aldi.co.uk/jump-starter-powerbank/p/734357767356600

[Cyker]

On 2/29/2024 at 6:00 PM, RickyC said:

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 )

I often wondered this; The only thing I can think of is deep-cycle batteries are not rated for automotive use or something

 

23 hours ago, Dexter290 said:

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

Oooh what road is that then? Asking for a friend...   

 

5 hours ago, CPN said:

A replacement battery should only cost you at most ~£75 if you buy it and fit it yourself NOT from the dealer. Keep looking back through this thread and you will find the links...

The Mk3 uses a different Battery to the Mk4 - The much more expensive AGM type. It's one reason I'm not that bothered about the relatively caveman-era Battery they put in the Mk4 - It's a darn lot cheaper to replace!!