Checking out a well used battery.

[kingjamez]

Besides looking at 100% rated miles, is there anything I can do when looking at a used Tesla to determine the health of the battery?

When I bought my leaf I used an OBD2 reader to get info from the BMS.

I'm going to inspect / buy a 2015 Model S 70D with 70k miles on Monday night. Are there any diagnosis I can do before I buy?

-Jim

 

[mblakele]

Good luck with the inspection!

I guess you already know to expect RM around 5-10% below original capacity? I'd think a 70D might be around 216-228 at 100%. Sounds like the battery should be under warranty until 2023, so you have that safety net. There's no explicit capacity guarantee in the warranty, but it should help if a whole module has gone bad or something like that.

When you inspect the car, I'd record both rated and ideal miles. Here on TMC I've read that Tesla has occasionally changed how rated miles are calculated. Ideal miles are supposed to be closer to the raw estimate of battery capacity. But it's still an estimate. I'm not sure what the 70D spec was for ideal miles, but maybe someone here will speak up.

I don't think it's easy to get more detailed information without special access. You could look into tools like TeslaFi or Tesla Spy, but I'm not familiar with them.

You might also try to get a photo of the battery sticker, from the passenger-side wheel well. After 70k miles it's possible that the original pack has been replaced.

The rest of the car is out of warranty, right? Or is there an extension that will transfer with the car? Either way I'd pay special attention to known problem areas like door handles and MCU. I don't know if you'd have any luck getting service records from Tesla, but it's worth a try.

 

[kingjamez]

Thank you very much.

I just talked with the seller again and he said that the battery was currently being refurbished by Tesla and that it's got a loaner battery in it right now (seems like a 75kWh loaner since he said it gets 250 at 100% now). This "seems" like a good thing to me since the refurb battery will have been checked out by Tesla before re-installation.

He said previous to the battery being replaced it was at 220 at 100%, which seems low but not well out of the norm.

Yes, it is out of warranty save for the battery and drive train. Two door handles were replaced 6 months ago and the owner is going to get the service records for me from his service center.

Again, thanks for the advice. I'm pretty convinced I'll go through with the purchase tomorrow night barring anything extremely odd when I see it.

-Jim

 

[henderrj]

You can call Tesla, a service center, and ask specific questions about the car. Ask if it has the cold weather package, for instance. In other words, check on whatever he told you. Of course if he has the monroney sticker you can just look at that. You can also ask them specifically, is the battery in repair? They can't give you general information but they can answer specific questions. At least they did when I bought mine from a third-party.

 

[kingjamez]

Thanks again all. When I went to purchase the car, the seller called the service center about having his original battery sent to my service center and he was told that he could just keep the loaner battery. So, now I have what was originally an S70D but is now an S75D... pretty cool.
Nice to finally own an S... now I'm kind of torn on what to do with my 3 reservation.
-Jim

 

[Chaserr]

The battery's health shouldn't be a concern, it's warranted until 2023 no matter how many miles it has over that time and those batteries don't have a troublesome reputation anyway.

 

[AmpedRealtor]

Service can access a "CAC value" for the battery. Apparently this is the best way to determine the health of the battery, not necessarily by looking at estimated range. Try asking the owner of the car you are considering to ping Tesla Service and ask for his CAC value. Not sure if they will provide it, but that could be a useful data point.

Battery health: What is the ideal CAC ?

 

[jelloslug]

Thanks again all. When I went to purchase the car, the seller called the service center about having his original battery sent to my service center and he was told that he could just keep the loaner battery. So, now I have what was originally an S70D but is now an S75D... pretty cool.
Nice to finally own an S... now I'm kind of torn on what to do with my 3 reservation.
-Jim

If the $1000 is not killing you, just keep the reservation for the time being.

 

[kingjamez]

If the $1000 is not killing you, just keep the reservation for the time being.

That's the plan for now... Just can't really see giving up the S, it's just such a great car.
-jim

 

[kingjamez]

Service can access a "CAC value" for the battery. Apparently this is the best way to determine the health of the battery, not necessarily by looking at estimated range. Try asking the owner of the car you are considering to ping Tesla Service and ask for his CAC value. Not sure if they will provide it, but that could be a useful data point.

Battery health: What is the ideal CAC ?

Since I own the car now. I'll ask the service center next time I'm there. I think it's a valid question given that I'm now permanently using the loaner battery.
-Jim