[MolarBear]

Hi all,

Went to BMW Park lane today, viewing an 18 LCI Coupe. Had a call 1 hour before my train - telling me that when they went to get the car to wash and prep it, the car's starter battery was flat.

The sales girl told me that they couldn't jump start it, and would completely replace the battery in it. They would have to call their service dept who would do it over the next few days. I couldn't even inspect the car as it was in their dark car park, badly lit, and the battery was completely dead.

Tesla-info tells me that they originally listed the car in January (some 6 months ago) and hadn't sold it over lockdown, it's clearly been stagnating for months and months, without being charged!

I put the deposit for the car on the condition that the car would be inspected again by me when collecting and all faults fixed, and now started reading up a little on the train home. I've just read in the manual (pg 190, attached) that excessive discharge can cause the battery to be damaged. Does anyone know if the main battery would be stuffed in the long run from them not charging it over 6 months? As I said the starter battery was as dead as a dodo.

Or if the service techs can provide a % of battery life / status? Should I push for a new main battery to be put in too?

To top it off it was a very underwhelming sales experience, from BMW Parklane. I felt like royalty when I went for a look around at my local Yorkshire Ferrari dealership. Buying a £60,000 car today and I felt rather underwhelmed and definitely did not feel exclusive at all from their flagship dealership!

Cheers!

[Maxxsirrah]

Theres another thread on here, not too long ago about the issues one fellow forum member had after dealing with a completely flat i8 battery..... Its not a good story, take a look, it was fairly recent.

[MolarBear]

Thanks. You mean this one - https://bmwi.bimmerpost.com/forums/s...t=flat+battery ?

The car has 18 months warranty remaining so it would cover failure in the next 18 months. My biggest fear is that battery degradation/damage has already occurred, and when I was meant to be looking forward to essentially a new battery (3000 miles on the clock only) I'm getting a damaged battery, in the same way your phone needs charging a lot more 6 months in compared to brand new!

[Leto1701]

I have a simple advice. Don't buy it. LiIon Batteries take permanent damage from two things:

1. Sitting in high temperatures fully charged at high voltages. In this scenario, parasitic processes cause permanent battery damage at the electrodes. For the i8 other than the Teslas e.g. you don't need to worry so much, BMW sacrifices some capacity by not allowing charges very close to max. voltage to protect the battery. A PHEV will typically get charged to 100% all the time and sit at 100% all the time so that mechanism is required. In a Tesla you must not do that, to claim maximum theoretical range they allow full voltage charges to the real 100%. Typically, owners who want to protect the batteries charge a Tesla only to 80%, some only 60%.

2. Deep discharge. This will ultimately also damage the electrodes by parasitic processes in the electrolyte. The inner battery resistance rises and capacity gets permanently reduced. There is also a protection mechanism against this, that also Tesla implemented because otherwise people running the battery flat would have a 30.000$ repair bill. BMW's 0% charge means there is still a safe charge level in the battery. Again, that's important because a PHEV is designed to drain the battery completely. But only to charge it soon. I wouldn't let it sit at the Airport with empty battery for a couple weeks, rather go to Sports mode on the last miles of the trip and charge it to 50% if there is no charger at the destination. Flat for months will cause damage because of the slow creeping discharge of any battery over time.

The "window" you can actually use from the battery is dynamic to compensate for aging, so you slowly get closer to the real 100% and the real 0% because the battery management system increases the window to always give you the same capacity. Of course that process has limits.

In your case, you might have already a dramatically increased window although you don't notice any degradation of range, etc. yet. It will most likely hit you after any warranty and that anyway covers failure, not degradation of capacity. If your range goes down 20% it will be hard to claim a warranty case.

Hands off any EV that had a potential deep discharge over a long period of time.

[MolarBear]

Thanks Leto. I completely understand. I've already signed the deposit agreement and the rest of the forms but that was before I was aware there could be a chance of the battery being damaged.

Either way it was clear I could not inspect the vehicle. It was a 5 hour return trip and I hadn't occurred to me at the time that there was a chance of battery damage hence signing the agreement. I've written a very strongly worded email to the sales manager to ascertain the condition and also to get them to agree liability if it suffers damage in future, post warranty. See if that works...

[Leto1701]

Good luck. And have fun with the car!

[MolarBear]

Thanks! Do you know if the i8 has a capacity test? The i3 does, not sure if there was an i8 secret menu?

Thanks again!

[Maxxsirrah]

Originally Posted by MolarBear

Thanks. You mean this one - https://bmwi.bimmerpost.com/forums/s...t=flat+battery ?

The car has 18 months warranty remaining so it would cover failure in the next 18 months. My biggest fear is that battery degradation/damage has already occurred, and when I was meant to be looking forward to essentially a new battery (3000 miles on the clock only) I'm getting a damaged battery, in the same way your phone needs charging a lot more 6 months in compared to brand new!

Yes, thats the one I was referring to. The battery does come with an 8 year warranty remember though and I think that it covers both a complete failure of the battery and also degredation to below 80% of its original capacity. Worth checking that with the dealer. Might be worth trying to agree to a full money back return in the first month in the event that you get any failure in the electric drivetrain.

[MGRMLN]

Originally Posted by MolarBear

Thanks! Do you know if the i8 has a capacity test? The i3 does, not sure if there was an i8 secret menu?

Thanks again!

I would also like to know! Thank you!