Battery health check on 2nd hand car?

[Dudeist]

Hi, thinking of taking the plunge on a 2-3 year old ID3 with ideally about 20k mileage. I saw on previous thread to check software version and for any recalls using VIN. But can a VW dealer provide a meaningful % state of health (SoH) battery reading? They say warantee will cover if it goes down to 80%, but obviously I would like reassurance it is well over 90%. Cheers for any help.

[Dudeist]

PS I saw the readout on a 58kWh model said 43% / 78miles remaining, which would scale up to 180 miles at 100%. But not sure if that can reliably deduce much.

[sidehaas]

I believe some VW dealers can, but probably not all, and I'm not sure it's worth much really. It's worth asking the dealer though. The warranty is actually to 70% after 8 years / 100k miles.
You shouldn't read anything in to the GOM, especially if they have had it doing lots of short drives with the heating on.
If you are familiar with OBD and carscanner app you could try plugging in on a test drive. The car will give out a maximums energy content figure and also you can see a readout of cell voltages. You won't get an accurate degradation figure but if there are no cell voltages that are obviously well below the rest and the maximum energy content figure is somewhere in the 50000s then you'll know there is nothing majorly wrong with the car (our maximum energy content varies between 54-55000 and it's about the age/mileage you are looking at. It definitely has some degradation but the efficiency has improved since new with software updates so the usable range isn't much changed.)

[Dudeist]

Many thanks sidehaas. I will certainly get an OBD and monitor the battery once I buy. One of the cars I'm interested in with under 20k miles is "back at the battery centre having some work done ". I'm not sure if that's good (as it will have been checked) or bad (as it needed to go back). Do you or anyone have any thoughts on that?

[sidehaas]

Many thanks sidehaas. I will certainly get an OBD and monitor the battery once I buy. One of the cars I'm interested in with under 20k miles is "back at the battery centre having some work done ". I'm not sure if that's good (as it will have been checked) or bad (as it needed to go back). Do you or anyone have any thoughts on that?

If it's actually at the battery centre dealer remote from the dealer who owns the car, it almost certainly means it is having a module replaced following the recent recall check like mine. Ultimately it should be a good thing, the recall is to resolve a manufacturing defect rather than due to degradation but you get a new module. The downside though is not knowing when the work on that car might be finished - you could wait for it, but I wouldn't hand over cash until you've seen it if you want the car soon.