Battery Protection Limit

[Johnnyboycar]

After they said it was fixed.
Problem is exactly as it was before it went in the dealership.

[Deleted User 3123]

So it seems whatever they did made no difference but possibly just changed the message slightly at best?

If it’s any comfort it’s exactly the same on the VW ID range also - including the id7 with latest software http://id7forums.co.uk/viewtopic.php?p=239

Which I think makes it better - there will be far more focus on VWG fixing this properly.

My understanding is now, that the 12V battery will need to be replaced as they are effectively damaged but this was caused by some software issue effectively letting them get damaged.

I’m wondering if it is down to excess battery drain when the car was being transported last winter which is when a lot of the 85s were made obviously. Then the dealer just charged the 12V before handover when charging the car itself, which was enough to keep it ok in the summer but in the winter the damage has been done!

[Aragorn]

What needs to be figured out, as a starting point, is if the 12v battery IS actually flat.

Basic diagnosis 101. The car is claiming the battery is flat. Firstly you need to know if that is true, because the answer to that will guide the rest of the process...

If it IS true, then there are essentially two possibilities from there. 1. the battery is healthy, but the car for some reason is putting undue load on the battery and running it flat, or 2. the battery is broken/faulty and has much less capacity than it should, resulting in it running flat prematurely.

If its NOT true, then its clearly a software issue of some sort.

It could even be a combination, eg there WAS an issue causing the car to drain the battery which is now fixed, but due to the repeated draining, the battery is now broken.


A few folks seem to have had batteries replaced, have these people had any recurrance of the issue?

[Deleted User 3123]

From my understanding some have had it reoccur after 12V change but it took awhile - and these new batteries were then checked as also being damaged - resulting in a third battery etc.

Those that had some sort of software update and the battery replaced generally don’t seem to have the issue.

This is generally all 4th or 5th hand info so should be taken at face value.

The message seems to be triggered when the 12V voltage drops below 12V I believe. 12.05 I think is ok and 11.95 isn’t.

But the cars should charge the 12V from the HV when the car is off which means this should never ever happen. Hence the software issues, and 12V battery’s getting damaged, and why it’s on ŠKODA, VW and other group cars also.

I’ll be waiting for the software fix to be common knowledge and rolled out, and then get the car booked in for a 12V replacement after it’s done if needed ( assuming OTA). It shouldn’t be needed as the HV should keep it topped up anyway - just more often.

[Gd2]

My car is currently booked in for January (booked in last week and January was the earliest they could do apparently!)

I've hooked up a battery monitor to see whats going on. See below.

I've marked up the graphs with some of my thoughts but i suppose you can make your own interpretations

Overall - the battery seems to be charging and maintaining voltage but for the odd voltage drop to around 12.0v due to load from systems waking up, however i'm still getting error notifications and the car is disabling 12v systems.

KESSY is disabled at the moment and the battery voltage is sitting idle at 12.79v - surely this is a normal state of charge and the systems should be working?

[Deleted User 3123]

Where are you measuring that? At the battery itself?

Don’t suppose whatever you’re measuring it with can also measure the temperature at same time?

I strongly think that there is something that’s similar to….

If temperature is greater than 4’C then battery protection active if less than 12V

If temperature is less than 4’C then battery protection is active is active if less than 12.8V

Possibly something else if less than 0’C also.

Or similar… but you get the idea.

You will notice in the ŠKODA manuals and the VW manual there is a red warning for charging a frozen battery.

I still believe that this is all semi intentional by VWG and stops the battery charging for whatever reason (reduce warranty costs), by switching loads off instead of charging on.

I just think they have the temperature and voltages etc wrong in the 4.0 onwards cars which will get fixed hopefully soon. Then any damage from batteries going too flat etc can be fixed as required.

Remember on an ice and phev - the battery would get some heating from the engine heat alone - likely enough to delay a drop to below 4’C long enough that this is likely not noticeable or a problem as the car would need to be left for a day or so and not just a few hours.

[Aragorn]

Yeah that certainly doesnt look like the battery is actually dropping low enough to cause issues.

What monitor did you use? The ubiquitus BM2 or something else?

I tried to order a BM2, picked the wrong listing and ended up with something somewhat crappier.

[GT1]

I had one battery message today - to use remote etc but everything seemed okay??

Sell it before it drives you bonkers!

I've only had it for a couple of mths!! I love the car & hopefully VW/Skoda will sort this glitch out fairly quickly! Fingers firmly crossed!

[Gd2]

This is a bm2 type monitor, accuracy is pretty good (within +- 0.02v of a multimeter)

[Deleted User 3123]

See the attached email I got from ŠKODA after contacting them.