12v battery maintenance, issues, etc.

[ChrisWilko]

5 hours ago, Max_Headroom said:

Could you tell us exactly how much you use the car every week.

The wife drives it 2 miles to work and 2 miles back, four times a week (8 trips in total).

It then gets a 4 mile round trip to do food shopping, once a week.

Other trips are usually short hops here and there, usually 1-5 miles.

I sit in it and run it for 1hr, once a week.

[ChrisWilko]

4 hours ago, Mooly said:

So we assume it was fully charged although we have no idea what the actual capacity vs the rated capacity is.

So now totally discharged over say 18 hours. What is the rated capacity of these 'smaller' batteries? I recall around 36Ah give or take. If your battery were at that capacity then you would have to be pulling a couple of amps for those 18 hours and that is not insubstantial. It would generate a lot of heat if something were drawing current.     

 I think think the most likely scenario is just that the normal lowish (but still excessive in the scheme of things) background current draw has caused the battery to deteriorate over time. Something like your dashcam might be contributing to this because even when 'off' it may still have a quiescent current draw. Only way to know is to measure it.

It doesn't need much on a 24/7 basis to kill a battery. The battery technology used (lead acid type that is a couple of century's old) is not suitable for this type of use.

 

Yeah, I'm not sure about the rated capacity to be honest.

I can't see why this 12v adapter wouldn't be providing even a mildly accurate reading - not that disparate anyway!

I'm baffled what would drain it to unstartable in such a short period of time.

I guess I need to get it booked in.

[Derek.w]

12 hours ago, ChrisWilko said:

Further to the above, I've been doing the 1hr running charge on ours. 

I also picked up a 12v adaptor that shows the 12v voltage. It was on 14.2 when we got home yesterday afternoon, so perfectly within limits.

The wife went out to it this morning and it's under 11v (lowest measurement) and won't start.

There must be something malfunctioning or not switching off, and draining the battery. I've got a dashcam wired to ignition live, but I've had that out of the car and checked it; if it was running then it would have recordings on the SD, but it doesn't. It switched off as it should. No internal lights on, as the car is visible from our door cam.

Moving house at the moment, so I've not had chance to get it booked in. Not what I need at the moment, trying to sort out a million and one other things. 🤦 

A 14.2 voltage is showing its charging & not that it fully charged fully charged it will read 12.7 or 12.8 volts.( Thats the voltage when the charger has now switched off & Battery starts to drain.)

[Derek.w]

On 11/2/2023 at 11:03 PM, anchorman said:

This is it

 

 

Thats the one I fitted to my Yaris in May/22

[Derek.w]

Location under the rear bench seat you can access it from the front of the seat without removing the bench cushions.

[Cyker]

2 hours ago, ChrisWilko said:

Yeah, I'm not sure about the rated capacity to be honest.

I can't see why this 12v adapter wouldn't be providing even a mildly accurate reading - not that disparate anyway!

I'm baffled what would drain it to unstartable in such a short period of time.

I guess I need to get it booked in.

It may be the Battery has just degraded too much - One thing about the starter-type of lead acid batteries used in the majority of cars is they need to be kept as close to 100% charge as possible for as long as possible; As soon as they're at a lower charge than that they start to degrade, and if they are discharged below 50% they loose significant capacity.

A lot of us suspect the cars have been left in e.g. holding areas and allowed to discharge to zero or near zero too often before they get to the dealer, and also the 12v batteries seem like cheap ones rather than good quality ones. Those things combined would explain why the new Yaris seems so prone to 12v Battery discharge.

 

[Mooly]

10 hours ago, ChrisWilko said:

I'm baffled what would drain it to unstartable in such a short period of time.

I suspect the cause is a lowish constant current draw that causes Battery deterioration.

New Battery, 100% capacity and you take 10% out of it by leaving it for a couple of days. You drive for an hour and it is back to 99%. You leave it a day and its down to 97%. A short run and its back at 98% and so on. Its a slow but constant decline day after day.

This type of Battery would need a prolonged float charge to bring it back to 100% but that would only work provided the battery was never allowed to reach a low state of charge.

Once the charge is down to the 70% or less region (and has been left like this for a long time) you are into permanent damage and a loss of capacity that can never be recovered.

 

7 hours ago, Cyker said:

A lot of us suspect the cars have been left in e.g. holding areas and allowed to discharge to zero or near zero too often before they get to the dealer

This has long been suspected and I would go as far as to say it would be worthwhile for any new owner (new car just delivered) to do a real world discharge test on the battery to make sure it appears to have its rated capacity.

I appreciate that is not easy for most owners as it would require a known load (an electrical consumer) being run and monitoring the battery voltage. For example an old single conventional headlight bulb of 55 watt rating would draw just over 4.5 amps and run for around 7 hours before a 35Ah battery was fully discharged. You shouldn't go that far in a test but leaving something like that for 3 or 4 hours should not see the loaded battery voltage fall below around 12.1 volts.

If the battery on a new car can not do this then its duff from day #1

Having done a test like this the battery should then be fully charged back to 100%

 

 

[anchorman]

It’s all well and good knowing what might cause it and what tests can be done to substantiate Battery health but 99.9% of owners just want to own and drive the thing when they want to.  This is a similar situation to the owners of diesel cars feeling obliged to keep driving if their cars have started a regen before they reach home to avoid dilution problems.  It’s not fair to expect them to go to extraordinary lengths in order to keep out of trouble.  We know the system is good because it works well and has done for years on other models so if the calcs say the Battery is of suitable capacity then the Battery needs to be of suitable quality.  It isn’t fair to expect the owner to give up the car for two days of testing that might result in another tat battery, they need something that will be up to the job.   I’ve got enough trusted evidence now on a number of cars that demonstrate that owners are not under using their cars when this happens and the battery just drops off the edge for no apparent reason.  I can get Yuasa 5000 (5 year warranty) for £83 all in and I’ve fitted that many I can do it in about 15 minutes which I do for nothing for my mates but is it fair they do this at their own expense.  I’m never ever quick to blame the manufacturer and I was one that even in the face of numerous complaints, kept an open mind about these issues (and if I’m honest, suspected misuse) but I don’t any more, I lay the blame on these Turkish batteries.  Come on Toyota, take responsibility.   

[Mooly]

41 minutes ago, anchorman said:

It’s all well and good knowing what might cause it and what tests can be done to substantiate battery health but 99.9% of owners just want to own and drive the thing when they want to.

Exactly, at the end of the day you want (and should expect) something that just works. The myriad threads and posts on these issues show that goal hasn't been met and yet there is no definitive reason as to what is going wrong.

It would be so easy to rig a test vehicle up with a current monitor (measuring voltage just doesn't really cut it here) and log the discharge rate over say 7 days. I've never seen anything like that published.

Its pretty obvious that this Battery issue is widespread across not just Toyota but other makes and models as well. There is nothing to beat 'customer usage' to find out design defects that just don't show in design and development despite months of testing and millions of miles covered in development.

I don't believe there is a easy fix for this although I would bet next generation vehicles will be much improved. Low power (micro power) design of the background electronics is what is needed possibly along with a more aggressive charge regime when it is in use.

42 minutes ago, anchorman said:

Come on Toyota, take responsibility.  

That is what needs to happen.

 

[Max_Headroom]

Quote

It’s all well and good knowing what might cause it and what tests can be done to substantiate battery health but 99.9% of owners just want to own and drive the thing when they want to. 

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.    

[Max_Headroom]

1 hour ago, Mooly said:

It would be so easy to rig a test vehicle up with a current monitor (measuring voltage just doesn't really cut it here) and log the discharge rate over say 7 days. I've never seen anything like that published.

I thought there were many examples of this posted in the thread.

[Roy124]

A thought on prevalence. 

Many people come to this forum when they have a problem.   Many no doubt have problems but don't come here.

What we don't know is how many neither have a problem nor come here.

It is likely that what we see are skewed figures. 

[Graham47]

1 hour ago, Max_Headroom said:

i believe owners having these issues simply dont drive them enough.

How then do you explain those ‘low mileage’ owners who haven’t had problems or those ‘higher mileage’ owners (mainly appear to be around 21-22 MY) who do ?

 

1 hour ago, Max_Headroom said:

*obviously some cars will have duff batteries but that will be the minority.    

Do you have figures to back this ‘statement’. (See above).

[Max_Headroom]

37 minutes ago, Graham47 said:

How then do you explain those ‘low mileage’ owners who haven’t had problems or those ‘higher mileage’ owners (mainly appear to be around 21-22 MY) who do ?

There are 67 pages in this thread i cannot remember many if any "low mileage" owners posting that they have had no issue, have you  any figures to back up your statement?

[Mooly]

2 hours ago, Max_Headroom said:

I thought there were many examples of this posted in the thread.

I can't recall seeing one. Current draw logged over a decent time period that the car is inactive is what is needed rather than just Battery voltage.  

[Graham47]

24 minutes ago, Max_Headroom said:

have you  any figures to back up your statement?

Yes… me.

We also have reports of dealers replacing batteries without much persuasion.  That tells me they know something.

[Mooly]

2 hours ago, 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,

That is a logical assumption but speaking from real experience it is not always so. My fathers old Corolla did as few as 500 miles a year for a couple of years and only a 1000 or so in other years from around 2014 to 2019. It stood outside on the drive and never suffered any Battery issues and in fact last had a Battery in 2012 due to suspicion of leakage. The car is 21 yr old next year.

2 hours ago, Max_Headroom said:

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 think you could be right on that and this is something that again would be easy for a proper investigative test.

Again we need to see current into the Battery when beginning charging from a known partially discharged battery state into an otherwise healthy (new) battery. An ICE with alternator can deliver upwards of 70 amps and more at little over idle speed and not much lower than that at idle. Remember it can cope with lights, heated window, wipers, blower etc at idle without the battery entering a discharge condition.

I remember reading decades ago that an alternator can never fully charge a battery and at the time I couldn't understand why. Surely it can. Only in later years have I come to realise what was probably meant by that blanket statement and it is that the alternator with its fixed 14 or 14.4v output will quickly bring a battery to a high state of charge but would then need to run for a very long time (perhaps 30 hours or more) to fully charge the battery and of course that never ever happens.

Does anyone know the current output capability of the DC/DC convertor used in the hybrids for charging the 12v battery and powering all the 12 volt equipment?

That is another missing piece of information to me.   

[Cyker]

You can't really compare newer cars to older ones - With older cars, when you turned them off, they were off.

With newer and newer cars, there is more and more standby current drawn to run the computers. The Keyless Entry system seems particularly thirsty, as disabling it seems to extend the standby time of the 12v Battery, and is something we've recommend people do if they're going to leave the car standing for long periods of time.

I suspect the always-connected internet that allows you to remotely power on e.g. the HVAC or see car stats also adds a considerable power draw.

[Mooly]

2 hours ago, Cyker said:

You can't really compare newer cars to older ones - With older cars, when you turned them off, they were off.

Well up to a point but the ECU, the immobiliser, the receiver for the locking and unlocking from the key and so on are all powered on a car like the old Corolla.

The secret is in micro power design and I think this is where the failings are. Manufacturers have just totally underestimated how lead acid Battery technology is unsuitable for this kind of application.

  

[Cyker]

One difference is the remote systems are passive listeners, which doesn't need much power, but the smart entry systems are active and continuously ping, which uses a lot more power.

But you're right about the power - The batteries are not scaling up with the increasing amount of electronic crap that gets loaded into modern cars.

It's kinda funny as the Battery in the Mk4 is literally the lowest tech type of lead acid Battery - Even my Mk2 had an EFB, and the older Mk3 Yaris hybrid had an AGM Battery!

The one in the Mk4 is just a normal flooded lead acid starter battery like we used to use in like, the 1980's!  

 

[Max_Headroom]

4 hours ago, Graham47 said:

We also have reports of dealers replacing batteries without much persuasion.  That tells me they know something.

Where are all these reports?

All that tells me  is Toyota are replace whatever parts need replacing under warranty as they are obliged to, i believe it has been said in the thread leaving the Battery low all the time will damage it therefore the people who dont drive often and are having these issues are having their damaged batteries replaced nothing more!

[Derek.w]

The problem with a voltage reading is if you just put a charge through the Battery then before taking a reading you need to turn on headlights for a couple of minutes or just leave it standing for at least a couple of hours before taking a reading.

Otherwise you get a false reading.

Yes some systems take a voltage reading when the Battery is under a TEST load for a more accurate reading ie. using a Battery load tester to determen the state/ability to hold its rated charge of a given type/ampage of battery.

[Graham47]

3 hours ago, Max_Headroom said:

Where are all these reports?

In the preceding 67 pages and also FB.

You must also have read reports of owners struggling to accept it’s a warranty claim and is down to low usage or have paid for their own replacements.  Other dealers have not.

[FROSTYBALLS]

3 hours ago, Max_Headroom said:

Toyota replace whatever parts need replacing under warranty as they are obliged to

Could argue that it isn't a warranty issue.

The warranty covers against manufacturing defects. For example, having a Battery go flat due to little use or whatever, which then damages the Battery so it won't hold charge, isn't necessarily a manufacturing defect.

[Max_Headroom]

9 hours ago, FROSTYBALLS said:

Could argue that it isn't a warranty issue.

The warranty covers against manufacturing defects. For example, having a battery go flat due to little use or whatever, which then damages the battery so it won't hold charge, isn't necessarily a manufacturing defect.

 The majority of  members here believe the 12v problem is due to lack of use many now have solar chargers, smart chargers and jump packs so they don't get caught out, others believe it's a faulty batch of Battery isssue if the latter is causing the problem it should be replaced under warranty.