Discharging to 0%, harmful or just inconvenient?

[CFrolander]

So my Model X was involved in an unfortunate accident recently:

And I took it to one of the three local shops that are certified by Tesla. There were a number of issues with this shop, but one that concerned me was that they allowed the car to just drain to zero percent. They would charge it when they needed to move it inside or outside, but only like 3 miles of charge. They were about to order parts, and it was going to be a month or two before they touched it again, and I wasn't too keen on it sitting at 0% this whole time so I called Tesla. The person I had on the phone said that there was no problem whatsoever with sitting at 0%, but depending on how long it sits it might take many many hours to go from 0% to get the first few % of charge back on the car. They said it won't hurt the car to do this at all, it would just be an inconvenience and since that would be for the shop to worry about It was no big deal at all.

I ended up moving the car to another shop in any case. The previous one left the car outside, and not sealed well so there was tree crap all inside the nice white interior which was not so thrilling to me, especially with monsoons incoming. The new shop keeps all their cars inside, so that's nice, and there were other concerns as well.

Anyways, so what's the story on the battery discharged to zero percent? I don't trust the story of the guy at the old shop, but I would generally trust Tesla since I called them and the guy on the phone was quite confident that there would be no issues whatsoever. Is discharging the battery to 0% simply an inconvenience, or is it actually harmful?

 

[posity]

Lots and lots of Li-ion research says that below 10-20% for an extended period measurably degrades the lifespan of batteries. It makes sense that the company line at Tesla is driven by a marketing approach rather than a science approach: don't scare the customers. Tesla does make a superb product and is certainly at the leading edge on Li-ion technology, but then why take the chance that the information you're being fed is not necessarily scientifically correct?

Why have folks work on your car that can't do a simple thing like keep it charged at 50%? If they aren't willing to satisfy their customer for simple (and I believe entirely reasonable) requests, what is it going to be like if you are not happy with their work?

I would consider it a blessing that you found out as early as possible that the shop really does not care about your requests - and find a shop that does.

 

[IdaX]

Discharging to 0 or near 0 isn't THAT big a deal as long as you plug it in right away once it gets down there. But I'm with posity that long-term storage at 0 or near 0 state is exactly what kills batteries. See if they won't just leave it plugged into a 120v socket all the time.

And very sorry to see the crunch in your beautiful Model X! I hope that the shop can make it whole again.

 

[xyeahtony]

There is a buffer to protect the battery at the bottom, but even that will have phantom discharges and over time that will vanish as well. Insist they charge to at least 20%.

 

[animorph]

I always seem to have to replace my laptop battery after letting it (accidentally) completely drain. Same for RC plane batteries. Drain them below a certain voltage and they might not recover. So yes, it is a real problem.

Probably not a big problem with Tesla's buffer, but no reason to tempt fate.

 

[Tozz]

Regardless wether this is harmful for the battery, I think it might not be too bad but it doesn't help either.. What I think is more important is customer satisfaction.

Most dealers wash a car when it has been in their shop for whatever reason (repairs, annual maintenance, whatever). Its a bit of customer service. For EV's I think charging the car could be the same. Tesla for example does this, they hook the car up to their DeCs.

I would think that for a _certified Tesla_ shop the least they can do is make sure the car has some charge to sit a few weeks. Best would be 60% (as ideal SoC for least battery degradation is between 50 and 60%). Ideal would be permanently connected to a low amp charge.

Personally I would be worried about leaving the car for weeks at 0%. I wouldn't leave my car there without sufficient charge. And in the end that is all that matters, a happy customer.

 

[thegruf]

I would expect to be "Tesla certified" they have to adhere to certain standards.
Allowing a customer vehicle battery to discharge to <10% will undoubtedly be one of those standards.

Sorry, but I would be very concerned about this and the high probability of degradation to your battery.

I would raise it with Tesla directly as a matter of urgency, collect as much evidence as you can including typical range for a set charge level when you took the car in and when you get it back, and get it moved to another repairer if you can.

 

[jboy210]

Crazy idea.

Is the car drivable? If so, have you considered retrieving it from the shop and only give it back to them when the parts are in and verified as correct. Delays in getting body parts on Teslas are well documented and I would prefer to get use of the car and maintain its battery systems, until they shop can start and finish repairs in short order.

 

[CFrolander]

Actually we had already moved the car to a much better shop when I posted this, mainly just for curiosity sake. Thanks for all the great info and suggestions!

 

[Shock-On-T]

Glad to hear you car is at a better shop, and thanks for letting us know.
Should definitely be kept around 50% for long term storage.

 

[Yinn]

I would expect to be "Tesla certified" they have to adhere to certain standards.
Allowing a customer vehicle battery to discharge to <10% will undoubtedly be one of those standards.

Tesla themselves has let my vehicle drop down below 10% so I wouldn't expect a Tesla certified to be any different.

Fun fact: Even if mobile access is disabled; you will still get notifications of an extremely low battery state of charge.