V10 and Battery "Degradation"

[trunks13]

I've seen a 5% loss of range way before V10, according to TeslaFi.

Looks like it apparently started with 2019.24.4 73fb1ab and has steadily gone down in range from there:

Date Charge % Battery Range Estimated Range At 100% Odometer Firmware Version Outside Temperature
07/19/2019 90 % 281.49 312.77 15,291 2019.20.4.2 66625e9 81.94 F
07/20/2019 90 % 281.49 312.77 15,339 2019.20.4.2 66625e9 83.36 F
07/21/2019 90 % 280.63 311.81 15,402 2019.20.4.2 66625e9 81.79 F
07/22/2019 90 % 281.48 312.76 15,417 2019.20.4.2 66625e9 82.64 F
07/24/2019 90 % 281.48 312.76 15,453 2019.20.4.2 66625e9 86.49 F
07/25/2019 90 % 281.49 312.77 15,462 2019.20.4.2 66625e9 86.07 F
07/27/2019 90 % 280.63 311.81 15,534 2019.24.4 73fb1ab 85.2 F
07/28/2019 90 % 278.06 308.96 15,602 2019.24.4 73fb1ab 86.58 F
07/30/2019 90 % 275.99 306.66 15,666 2019.24.4 73fb1ab 86.27 F
07/31/2019 90 % 273.85 304.28 15,712 2019.24.4 73fb1ab 84.36 F
08/01/2019 90 % 273.43 303.81 15,775 2019.24.4 73fb1ab 86.39 F
08/02/2019 90 % 270.84 300.93 15,819 2019.24.4 73fb1ab 87.16 F
08/03/2019 90 % 271.72 301.91 15,847 2019.24.4 73fb1ab 86.39 F
08/04/2019 90 % 272.56 302.84 15,941 2019.24.4 73fb1ab 86.4 F
08/05/2019 90 % 272.56 302.84 16,012 2019.24.4 73fb1ab 85.37 F
08/06/2019 90 % 271.72 301.91 16,039 2019.24.4 73fb1ab 86.35 F
08/07/2019 90 % 269.57 299.52 16,096 2019.24.4 73fb1ab 87.38 F

 

[earthwormjim]

Well I'm up to 228 miles at 100% state of charge. 8 miles of range improvement ever since V10 put me down to precisely 220 miles. First re-balance netted me ~5 miles of range, second 6 miles, third 7 miles, fourth 8 miles.

I'm done doing the re-balance procedure for now. Going to heed the high nickel cathode battery study posted on the forums by @321filip:
https://pubs.acs.org/doi/full/10.1021/acsenergylett.9b00733

Charge to around 60% for my daily commutes. Seems better for the cathodes to stay at 20-60%, with occasional dips to sub 10%, than 80-40%.

I'm able to charge at 277Vac with 24amps, so if I ever find myself having to make sudden unexpected errands or runs across SoCal, I can pretty quickly charge past 60% should I need the extra range. Plus there's a supercharging station within walking distance of my house.

 

[JoGee]

I don't trust that the trip meter is 100% accurate and includes all energy usage.

I have the same impression.

 

[321filip]

I'm done doing the re-balance procedure for now. Going to heed the high nickel cathode battery study posted on the forums by @321filip:
https://pubs.acs.org/doi/full/10.1021/acsenergylett.9b00733

Charge to around 60% for my daily commutes. Seems better for the cathodes to stay at 20-60%, with occasional dips to sub 10%, than 80-40%.

I would say go even lower
https://res.mdpi.com/d_attachment/applsci/applsci-08-01825/article_deploy/applsci-08-01825-v2.pdf

 

[n2mb_racing]

I would say go even lower
https://res.mdpi.com/d_attachment/applsci/applsci-08-01825/article_deploy/applsci-08-01825-v2.pdf

Hard to read that paper quickly, but I thought keeping the battery at low SOC was bad? I'd been worried about leaving my battery at 10 or 20% SOC on my eBikes...

Also, aren't there diminishing returns here? The big increase in lifetime comes from charging to 90% instead of 100%. What additional gains are there to be had going much lower? There's another study that shows 80-20% maximizes total energy out of the pack. Although, if it is in a car that doesn't drive very far, lower SOC could be better.

 

[earthwormjim]

I would say go even lower
https://res.mdpi.com/d_attachment/applsci/applsci-08-01825/article_deploy/applsci-08-01825-v2.pdf

Yes I read the paper. It doesn't seem necessary to go lower provided I'm not going above 60% (so 50 something displayed percent + the buffer). Getting below 10% is not easy to manage unless I drive dangerously slow on my commutes. I can only charge at work, so I have to ensure I have enough range to cover a round trip, and temperatures are dropping below 40F now in the mornings, making this even harder.

I think as long as I occasionally go very low, that should heal any cracks, and staying below 60% ensures the cracks do not reach the outer surface of the cathodes.

My last full rebalancing cycle went to 1%! That was hard to manage.

 

[n2mb_racing]

Another thought.... I doubt I will want to own this car once the warranty is up, so it doesn't really matter how long the battery lasts.