I had a 2014 Model S and remember all the discussion about best charging practice. I am about pick up a Software limited standard range M3 which reduces the range from 240 to 220 miles. Since the battery is being "limited" by around 10% does that result in a charge setting of 90% actually only being 81% in terms of its long term impact on battery degradation?
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Software Limited battery charge level
- Thread starter svoelpel
- Start date
AlanSubie4Life
Efficiency Obsessed Member
Lots of threads on this. Search for SR Battery
SR charge to 100%, Multiple charge cycles ok?
Apparently (I have no idea!), people have reported regen is available at 100% displayed SoC (220 miles) in the SR (not SR+), so that would imply it is at least partially "top-locked."
You'd have to have regen analysis comparison (or charge rate comparison possibly) under identical conditions between an SR & SR+ to determine exactly how much top lock there is.
SR charge to 100%, Multiple charge cycles ok?
Apparently (I have no idea!), people have reported regen is available at 100% displayed SoC (220 miles) in the SR (not SR+), so that would imply it is at least partially "top-locked."
You'd have to have regen analysis comparison (or charge rate comparison possibly) under identical conditions between an SR & SR+ to determine exactly how much top lock there is.
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darth_vad3r
Well-Known Sith
My math gives me 90% on an SR = 82.5% of an SR+ (it's 220 and 240, not 90% of 240).
AlanSubie4Life
Efficiency Obsessed Member
A bit off topic, but:
So are you saying the EPA document (which I think was about 54.5kWh discharge) corresponded to 247 miles? I had heard that number from Elon before of course but did not see it in the EPA submission (I was not looking).
So since they reduced it to 240 there would be less available energy than the 54.5kWh, at “100”%, right? (Scaled by 240/247?). Which of course would not be true 100%, if this is what they actually did....
However...
In other words...
My understanding is they have to make all the EPA energy available...but if they reduce the rated miles, are they actually allowed to take some of that energy off the table, or do they just reduce the miles?
For the LR RWD they voluntarily reduced it before increasing it again. Do we know whether this affected available energy? Or did it just affect the Wh/mi constant they use to display the rates miles? I was never clear on this, what actually happened.
247.2 mi is 70% of the combined EPA test result of 353.1mi. That by definition consumes all of the usable battery capacity, which was measured as 155.41 Ahr. Given a 350 nominal battery voltage, that yields 54.4 kWh.
They can only reduce the advertised range. They cannot reduce the battery capacity, as that would be blatant cheating of the EPA test, so the same usable capacity is available from fully charged down to below 0% when the car stops. The indicated 0-100% capacity is a smaller value.
darth_vad3r
Well-Known Sith
So then it’s 91.7% no matter what, right?
240 is either considered “240” or “97.2% of 247”.
220 is either considered “91.7% of 240” or “89.1% of 247”, aka “91.7% of ‘97.2% of 247’”
I don’t think the 247 enters the equation from a battery health perspective, does it?
You are suggesting it’s possible they took 11% off the SR+ battery capacity and labelled it as 91.7% of the SR+ range since they had some overhead wiggle room in the EPA numbers to start with. So the internal constant would be scaled differently in that case ... I guess they could do that ... but that’s a bit more involved change than a simple kWh charge cap which lets all the other numbers fall out naturally from the unchanged charge and discharge constants and calculations.
Hmmm.
I guess someone reading the CAN bus can verify the energy numbers at “100%”. I somehow doubt anyone with an SR has a CAN bus reader. Maybe.
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