Battery estimated capacity question

[Sti-g]

I think degradation threshold is 53.5kWh for your vehicle, but you could help with that by taking the energy screen picture but with the battery icon set to mi/km NOT %, and capture all three “key” numbers. That allows calculation of the constant, which in turn allows calculation of the threshold, since we know the max rated range was 263mi.

I finally got around getting the info. It has been pretty cold here but this week temps are around 50-55F. I used the energy app to get decimal point for SOC.

SOC: 74.2% or 178.3miles
Consumption: 196Wh/mile
Projected range: 187miles

How do you calculate degradation threshold?

 

[AlanSubie4Life]

I finally got around getting the info. It has been pretty cold here but this week temps are around 50-55F. I used the energy app to get decimal point for SOC.

SOC: 74.2% or 178.3miles
Consumption: 196Wh/mile
Projected range: 187miles

How do you calculate degradation threshold?

If that 178.3 miles is read from the energy screen (I guess the new one has decimal point? Have not been paying attention)… then:

196Wh/mi*187mi/178.3rmi = 206Wh/mi

206Wh/mi*263mi = 54.1kWh is the degradation threshold.

If you could post pictures (careful to crop out identifying info) for posterity that would be great. They are better for documentation.

But thanks regardless.

 

[Sti-g]

If that 178.3 miles is read from the energy screen (I guess the new one has decimal point? Have not been paying attention)… then:

196Wh/mi*187mi/178.3rmi = 206Wh/mi

206Wh/mi*263mi = 54.1kWh is the degradation threshold.

If you could post pictures (careful to crop out identifying info) for posterity that would be great. They are better for documentation.

But thanks regardless.

Thank you for the calculation.
attaching screen captures.

 

[AlanSubie4Life]

Thank you for the calculation.
attaching screen captures.

Thanks. Since I haven’t used the energy screen this way before, at some point I am going to double check on my car that the fractional rated miles calculation works out.

I don’t really have much doubt but want to double check.

I think this is a new firm datapoint - I was just guessing at the 53.5kWh before (not sure where I got it from). I think the 54.1kWh is closer to correct. Thanks for that.


Can’t really tell from the pics because it is hard to “drive to the line” but this 206Wh/mi number implies that “rated line” should be at 211Wh/mi or so. At that recent efficiency the lines should overlap.

 

[Sti-g]

Can’t really tell from the pics because it is hard to “drive to the line” but this 206Wh/mi number implies that “rated line” should be at 211Wh/mi or so. At that recent efficiency the lines should overlap.

I think I have to drive longer to get a better idea of the rated line. I took the pictures shortly after I started driving (of course, I pulled over to take the pics) to capture the decimal points because as you drive longer, the rated line extends and you quickly loose the decimal points.

 

[Dr_G]

Not saying your wrong, but…

“Logically” if you drive the car down to 0% SOC then the range will also show zero miles, but of course the car is still drivable owning to the built in buffer. The question is, what will the projected range show on the graph at 0% SOC? If it also shows zero then the result of the calculation in question should based on usable capacity.

Anybody tried this?

Yes. Drove it ~8 miles past zero. Diplay stayed at zero. QED

 

[Dr_G]

Here is a simple thought:

Instead of "Battery Capacity @ 100% (in Wh) = Avg Wh/mi * Projected Range / SoC%",
just use "Projected Range / SoC%"?

Since the guessometer calculator presumbaly takes driving habits (ie Wh/mi), into account, should that not be a reasonable estimate?

 

[AlanSubie4Life]

Here is a simple thought:

Instead of "Battery Capacity @ 100% (in Wh) = Avg Wh/mi * Projected Range / SoC%",
just use "Projected Range / SoC%"?

Since the guessometer calculator presumbaly takes driving habits (ie Wh/mi), into account, should that not be a reasonable estimate?

No. Just use the formula please. No need to reinvent the wheel by making up incorrect equations.

It’s not possible to say what the range will be, or even estimate it, without knowing a lot more. We can only know the capacity estimate.

Yes, your equation will give the range, roughly, assuming that same efficiency. But for reasons discussed elsewhere above, it is not even correct if you make those numbers exact and actually drive with that efficiency (it will involve driving into the buffer and you’ll hit 0% at around 95.5% of the expected distance).

 

[Dr_G]

No. Just use the formula please. No need to reinvent the wheel by making up incorrect equations.

It’s not possible to say what the range will be, or even estimate it, without knowing a lot more. We can only know the capacity estimate.

Yes, your equation will give the range, roughly, assuming that same efficiency. But for reasons discussed elsewhere above, it is not even correct if you make those numbers exact and actually drive with that efficiency (it will involve driving into the buffer and you’ll hit 0% at around 95.5% of the expected distance).

Thanks! That's what I was afraid of!

 

[AlanSubie4Life]

Thanks! That's what I was afraid of!

There is really nothing wrong with your formula (it is just equal to Battery Capacity / Avg Wh/mi, after you rearrange the original formula). But since battery capacity includes the buffer that means at that Wh/mi you’re going to drive into the buffer to achieve the value of Projected Range / SoC%. And Wh/mi is usually a moving target of course for many reasons.