Why not just get a OBD Dongle to read the true kWh in the pack reported by the car?? You can see actual data on your battery pack, take away any guess work.
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Teslafi - battery report. Should I be concerned?
- Thread starter pdk42
- Start date
Why not just get a OBD Dongle to read the true kWh in the pack reported by the car?? You can see actual data on your battery pack, take away any guess work.
Just not in the same way that the estimated range does, it might make a little bit of difference to rated range, but my rated highs and lows don’t correlate with temperature *at all*.
MrBadger
Badger out
Its still guess work by the car. Measuring capacity of a battery pack is a non exact science - you can't just measure its voltage at a single point in time and know exactly what energy capacity is there.
Lithium-Ion State of Charge (SoC) measurement - Coulomb Counter method - OCV
I believe I read something Tesla using something like the Coulomb Counting method (#2) hence why values can be recalibrated during high/low SOC cycles.
I suspect that the value that TeslaFi reads from the car from the API is derived from the same figure that the OBD dongle will be reading, just slightly less precision - difference between 1% and 1.99% is potentially 3 miles on a LR battery.
I’ve always just assumed that the API reports the percentage and rated range, and that TeslaFi just does the basic divide rated by percentage then multiply by 100. The numbers come out the same as doing the calculation myself.
MrBadger
Badger out
I'm pretty sure it does too, but the data that it uses will still be derived from the same info that the OBD dongle will be using, so hardly any more guesswork than is already being used other than the reduced precision hence my comment about 1.00% and 1.99%. Its just presented differently, one as kWh and the other extrapolated to miles, the latter potentially being up to around 3 miles wrong on a LR model due to precision and hence reason why TeslaFi has an option to limit to only completed charges to help mitigate some of this error.
Yep, totally agree with all that
I’m probably going to pick up an OBD adapter though, so I can at least see what kWh the car *thinks* it has.
Follow up, seems from a German thread online that SR+ Nominal Full Pack should be more like 50.x so I’m about 3kWh down. So about 94% current health based on kWh, whereas 215 of 240 is more like 90%.
10% degradation worse case, since Aug 2019 and 8k miles. Not complaining, just sharing the numbers.
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