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Just how degraded is my battery? Different techniques giving different results...

I bought a 70d Model S (with a locked 75kWh pack) last week. I'm trying to figure out how much degradation the battery has.

When I charge it to 100%, it shows 201 'typical' (i.e EPA rated) miles.
(side note: the fact that 'rated' miles in UK/EU cars are extremely different to 'rated' miles in US cars is something that I didn't realise until it was too late. In UK/EU, 'typical' miles are equivalent to what our American colleagues call 'rated' miles, and 'rated' miles are similar to 'ideal' miles)

Anyway I understand that, from new, this car had 240 EPA miles. This would imply a degradation of 16.7% and a remaining capacity of around 57kWh.

However, I get a much nicer number when I try this technique:
- I drive 30 miles without stopping.
- On the energy screen, I multiply the avg consumption by the projected range
- I divide this by the current battery % that is showing to get a theoretical total usable capacity in Wh
I've done this 3 times, at different states of charge (80% , 40%, 10%)
At 80 and 40, I get very consistent and similar results, implying a total capacity of ~63kWh
When I did it at 10%, I got 42kWh , which is obviously not accurate.

Furthermore - I drove the car from a SoC of 100%, all the way down to 19%. I did this over the course of 2 days, temperature about 12 celcius throughout. I got the following numbers, at 19% remaining SOC:
185.5 miles driven
262 Wh/mi average
48.5kWh total used

This would imply a total capacity of about 60kWh - I'd even be happy with this, it's better than the ~57kWh estimate I seem to be getting from the EPA range.

I'm just confused why these 3 methods - all of which should logically be yielding similar results - are so far apart from each other.

Which of these kWh numbers is most likely to be correct?
 
I should also add - I tried recalibrating the battery using the following method

- Drive the car down to 7%, park it overnight (interestingly I awoke to a completely dead 0% battery....)
- Charge the car back up to full, and keep it plugged in past 100%

In doing this my range increased from 200 to 201.
 
I have over 205k miles on my S. U will never ever get a perfect range. There r too many variables. Weather, speed,day, night.etc. when home only charge to 80%. Try not to let charge get below 20%, sometimes they die early. Always leave plugged in at home. See attached from users manual.
 

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Also take into consideration that when doing the calculus avg consumption x est range / % left, the rounding poses a problem but the bigger problem is if you have a low battery % as the rounding effect will mathematicaly increase. Better do this at high % battery remaining.
 
I should also add - I tried recalibrating the battery using the following method

- Drive the car down to 7%, park it overnight (interestingly I awoke to a completely dead 0% battery....)
- Charge the car back up to full, and keep it plugged in past 100%

In doing this my range increased from 200 to 201.
If you are losing 7% overnight then you either have something keeping the car awake or your 12volt battery needs to be replaced. I was losing 25% range per week. Replaced the battery and its now around 8% per week.
 

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