Help - Battery Degradation

[BoilerG]

I purchased a brand new S75 RWD, pre-uncork in May 2017. I researched battery degradation before buying and after my researched expected to see 5-7% degradation by 50,000 miles in a worse case scenario. I knew some folks saw 0% degradation, and it was worse for others.

I'm currently close to 10% degradation at around 28,000 miles. I almost never charge to 100%, I Supercharge to 80/90% maybe 4-6x per year. The degradation is to the point that I had to make an additional charging stop on a road trip due to loss of range, and I likely would have bought the 100D if I thought it would be this bad.

I'm also seeing some weird symptoms:

• On the rare occasions I fully charge, it can take up to an hour for charging to complete the last mile of charge.
• If my battery is low (less than 20%) and I set it to charge to 90%, it will always overshoot the mileage to 96-97% full (218 miles or so) but if I charge with a SOC>20%, a 90% daily charge will charge to 203miles
• I've opened multiple tickets with the service center and they said they would run battery diagnostics but they never call back and give me a generic answer when I finally speak with someone.
• I've been losing about 1 mile of charge capacity every 1,000 miles over the last 5k in miles so it's been getting worse at a more rapid rate.

I'm a huge Tesla fan, but I didn't expect my Tesla battery, which I baby, to degrade faster than my iPhone battery (which I abuse). I've also tried a number of things including:

• Let the battery run down to just 1-2 miles and then fully charge (I know this hurts the battery so I only tried this once as some of posted this can help reset the meter)
• I stopped using the Chargepoint at the offfice and only charged at home with my Tesla charger for some time, but I'm still losing range
• I tried waiting one hour after parking to charge as someone at service center said this would let the battery balance out
• I tried 80% daily charge for some time vs 90% charge, but didn't see any decrease in degradation rate.
• I tried one supercharging session to 100%. This seemed to help a little, but it took over an hour for the last mile of charge so I haven't tried again

Anyone have insights? My suspicion is I'm having some cell failure, but I find it ridiculous that it has to get to 20% degradation before Tesla will do anything. Thanks.

 

[Az_Rael]

Check out the first post of this thread:
Sudden Loss Of Range With 2019.16.x Software

Lots of good info there. You could also have a module going bad, but it will take a while before Tesla acknowledges that.

 

[SSedan]

I haven't paid much attention to the other batteries but I know earlier this year those of u with S85/P85 got a update that capped max cell voltage cutting about 10+ miles off 100% on my car.
When I bought it I saw 257 down from the original 265 which was awesome for 65K miles 2 years later at 92K I see as low as 242 on a full charge. This summer I did see 247 so I think some of what I am seeing is temperature related.

Supercharging speed has been significantly slowed as well.

Az_Rael posted while I was typing, looks like good reading.

 

[Tam]

...On the rare occasions I fully charge, it can take up to an hour for charging to complete the last mile of charge...

Do expect the last mile can take a long time. It could be less than an hour but if it's an hour or more, that is just part of what we sign up for if we really want to wait and watch for 100% charge to finish.

...If my battery is low (less than 20%) and I set it to charge to 90%, it will always overshoot the mileage to 96-97%

The Battery Management System would readjust the battery gauge with new data it reads from the cells so the old setting of 90% is now readjusted as 96-97%.

...I stopped using the Chargepoint at the offfice...

There's no reason that you should stop using non-Tesla chargers. The more you can plug in the happier.

...20% degradation before Tesla will do anything....

Model S and X do not have a capacity warranty (although Model 3 does have a 70% capacity warranty).

It's too optimistic to think that just because your Model S has lost 20% or more, Tesla would automatically deal with the issue as experienced by:

Infinite Mile Battery Warranty [Now] Being Honored By Tesla [Issue Resolved]

 

[Fredneck]

This sort of issue needs to gain attention of the media. How many people have been affected by this do you think?

 

[SSedan]

I have a P85 but don't use full throttle enough to have noticed a reduction, the 5% sudden range loss I could swallow since my car had been doing great on that front already.
The supercharger throttling is going to be a problem, I don't road trip a lot but most common direction is 180mile stretch and needed 50minutes there to continue on. If that is now 1:15+ wife and elementary school age kids are going to be displeased.

 

[BoilerG]

This sort of issue needs to gain attention of the media. How many people have been affected by this do you think?

Looks like lots of people with S75 RWD are having a similar issue.

What's your S 75 range at 90%?

 

[Inframan]

Heat related, like happens to the Leaf, but not as bad? I see you’re in Texas.

 

[cookie99]

Heat related, like happens to the Leaf, but not as bad? I see you’re in Texas.

passive cooling on the leaf sucks.

 

[AMPd]

Heat related, like happens to the Leaf, but not as bad? I see you’re in Texas.

Heat related? In November?

 

[Inframan]

Heat related? In November?

Perhaps the degradation occurred over the summer and the software is now showing it.

 

[Inframan]

passive cooling on the leaf sucks.

Yes, I know. But it’s why the Tesla actively cools the battery. Perhaps in hotter climates the Tesla cooling system can’t keep up. Which is why I said “not as bad.”

lastly, perhaps the cooling on this car is defective.
Maybe the car is driven a lot harder than others, even taken to the track.

either way it’s unacceptable to have the degradation. Just looking for a cause, so it can be addressed.

 

[Fredneck]

Yes, I know. But it’s why the Tesla actively cools the battery. Perhaps in hotter climates the Tesla cooling system can’t keep up. Which is why I said “not as bad.”

lastly, perhaps the cooling on this car is defective.
Maybe the car is driven a lot harder than others, even taken to the track.

either way it’s unacceptable to have the degradation. Just looking for a cause, so it can be addressed.

If the cooling was defective wouldn't the car notify someone and shut down?

 

[Sandy S]

I have an original Signature Model S P85 Serial #810 with 127,000 miles. I have lost 10% rated range when fully charged (238 miles compared to 265 when new). I have ordered another Model S LR 2020. The original MS was rated at 265 miles, while the new MS will be 373 miles rated!! Quite remarkable that Tesla's technology has increased dramatically with a substantial reduction in price. Originally the sticker was $106,000. My new MS is $81,000 with tech that totally eclipses my original MS. If your rated mileage declines below a projected range; try re-balancing the battery pack. Drive your car to less than 10% capacity and charge to 90% over three to four cycles. Then charge to 100% and see if the rated range returns to a more "normal" range that would be reasonable for the miles driven. During the seven years that I have owned my MS, my range appeared to decrease in excess what was projected from the posted MS battery degradation graphs that appear on a number of websites. However, after re-balancing the battery pack I had "recovered" some of the decrease in rated mileage. Hope this helps..

 

[maximizese]

I realize this post was from a few months ago and it would help if the OP gave an update. It seems like a number of pre-2018 Teslas have lost an unexpected amount of range since the June 2019 software updates, but we can't be certain that exhaustively explains the issue here.

I'd be curious to know the Wh/mi average of the OP from the good ole days of higher range, compared to the Wh/mi average of the reduced range. It's possible there is car may be using more energy for HVAC, drag/friction/resistance, etc.

It's also possible the cells aren't holding as much voltage as before, whether that's intentional software limitation or something the BMS is doing due to compromised hardware.

I hope you find you answers. It does seem weird that the car over-charges beyond the charge limiter; seems like something is wrong here.