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Battery Degradation Math

B0bski

New Member
Feb 9, 2020
1
0
Oslo
I have a '16 MX 90D with just over 29k miles.
It is my first Tesla and EV, and I got it used a couple of months back.

I know that it is not a brand new car, and I have read alot about degradation and range. Most of the time I accept the fact that the rangd is not what it used to be.

This weekend I took a longer drive and kept an extra eye on my consumption and range. Here is strange number I can not figure out.

Start: 100%
I reset the trip meter and started driving. Note that I did not stop apart from 3 red lights before getting on the highway.
On the highway I noticed 50% SoC.
The energy used meter showed 35kWh.
The math I can not figure out is how if 50% is 35kWh, is 100% 70kWh?
70kWh on a 90, how can this add up?

Could the battery degradate this much over 3 years? 18%!?

Thanks to all you smarter people out there. :)
 

Tam

Well-Known Member
Nov 25, 2012
8,233
1
Visalia, CA
...70kWh on a 90, how can this add up?...

It doesn't: That's whyTesla dropped numerical kWh and only calculate them as "standard, plus, long range..." so owners can stop calculating the kWh.

There are buffers so the useable kWh is not the full 90 kWh.

There are factors in calculating kWh too so your calculations don't add up if not taking in all factors.

My usual way to monitor the battery degradation is to charge it fully to 100% and see what's the rated miles displayed on the battery gauge and compare that with the EPA spec.
 
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MichaelP90DL

Active Member
Apr 19, 2019
1,543
0
Lancaster, CA
My usual way to monitor the battery degradation is to charge it fully to 100% and see what's the rated miles displayed on the battery gauge and compare that with the EPA spec.
That's what I do, too. I was hoping there's a simple way to calculate degradation (please don't ask me to do math, I totally succk at it), but so far haven't seen it. Tessie typically meets or exceeds the EPA number for indicated range, whatever that means (39,238 miles).
 

Bizz

Member
Dec 27, 2017
9
0
Norway
Drive the car from 100-0% in about 55 in 70F and then see what range you get. This eliminates heat loss and secures optimal range compared to Teslas range indications.
 

gangzoom

Active Member
May 22, 2014
1,151
0
Uk
Stop guessing and don't waste time with drives down to 0%, just get a OBD tool like ScanMyTesla or similar.

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