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Change in Range calculation algorithm?

I usually don't look at the range much and leave it on percentage but recently changed to miles before V10 to compare once V10 rolls out. Anyways, after a week with V10 one thing I noticed is perhaps for the RWD, 225Wh is not the power consumption per mile for range calculation.

I've noticed that even when a trip averages 225Wh/mile, 25 miles of driving is using 27 or 28 miles off the rated range.
I'm guessing could be because new rated range calculation is based on 215 or 220 Wh/mile.

I first got a hint of this when my range which has never showed more than 325 suddenly showed 327 the first time I charged to 100% after V10. I charge to 100 about every month for long trips.

Since then I charged to 100% again yesterday just to see and I got 327 again.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
14,206
18,279
San Diego
But I'm not talking about the displayed (rate) range - which I've not seen a reduction in. I think the algorithm for the calculation of rated range is changed (perhaps to hide a software limitation on battery?).

I doubt it has changed. I think the constant is either 222 or 223Wh/rmi for the LR RWD.

If you get a chance, remember it is most accurate to do a longer trip. And rounding error can lead to the magnitude of difference you saw.

Also remember battery should be at a steady state temperature for the entire test, and you can’t end the test interval with lots of regen (because those miles are temporarily hidden).

Not saying it has not changed - it is interesting that your rated miles went to 327 - it could have changed (to a smaller value of course). Let us know. Pictures are helpful.

Your datapoint suggests a consumption constant of about 210Wh/rmi - this sounds pretty doubtful and inconsistent with your 325->327 mile increase. (Would be a change from 223Wh/rmi to 222Wh/rmi.)
 
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@AlanSubie4Life
I see the standard rate as 240 Wh/mi in my LR RWD graphs....

The average is moving and depicted with a dashed line. You see that 238 is below the rated rate and 241 is above....

IMG_20191015_175238__01.jpg
IMG_20191015_175420__01.jpg
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
14,206
18,279
San Diego
@AlanSubie4Life
I see the standard rate as 240 Wh/mi in my graphs....

The average is moving and depicted with a dashed line. You see that 238 is below the rated rate and 241 is above....

View attachment 469226 View attachment 469225

That's correct. The line is about 239Wh/rmi or 240Wh/rmi. This implies the charging constant is 234Wh/rmi or 235Wh/rmi (the value used for the calculation on that graph is always 5Wh/rmi less for some reason, and matches the charging constant - I know, it makes no sense...), and the discharge constant is therefore very likely around 223Wh/rmi (about 4.7% less than the charging constant, for the RWD vehicles - for some reason it is 6.1% less for the AWD vehicles).

Constant and Line info

You can of course measure all these constants yourself if you wish - though you have that weird phantom drain and gain issue, so all bets are off for your results.

Note that based on some TeslaFi data I have seen, the discharge constant used by TeslaFi is also about 223Wh/rmi (looks like they might use closer to 222Wh/rmi). Sometimes hard to interpret their data, but if you know what you're looking for...
 
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I have been seeing some weird stuff lately, Was driving home from the work the other day and had a range of 164 and then after a couple miles of driving at about 240 wh/mi my range went to 167. I have never seen that happen before and no I do not have it on ideal miles or anything like that. Also in Teslafi, I have been seeing some range gains during idle and sleep. Nothing major but .5 to 1 miles here and there. Very weird.
 
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I doubt it has changed. I think the constant is either 222 or 223Wh/rmi for the LR RWD.

If you get a chance, remember it is most accurate to do a longer trip. And rounding error can lead to the magnitude of difference you saw.

Also remember battery should be at a steady state temperature for the entire test, and you can’t end the test interval with lots of regen (because those miles are temporarily hidden).

Not saying it has not changed - it is interesting that your rated miles went to 327 - it could have changed (to a smaller value of course). Let us know. Pictures are helpful.

Your datapoint suggests a consumption constant of about 210Wh/rmi - this sounds pretty doubtful and inconsistent with your 325->327 mile increase. (Would be a change from 223Wh/rmi to 222Wh/rmi.)
I'll start taking pictures to keep some better track
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
14,206
18,279
San Diego
164 and then after a couple miles of driving at about 240 wh/mi my range went to 167

A lot of possibilities. If this happened after a significant downhill this can happen; rated miles are not credited with regen until you accumulate an excess of about 3-4 rated miles (about 1kWh worth).

It can also happen if the battery was particularly cold initially.
 
A lot of possibilities. If this happened after a significant downhill this can happen; rated miles are not credited with regen until you accumulate an excess of about 3-4 rated miles (about 1kWh worth).

Hey Alan, so you are saying, a cold battery won't 'count' toward your wh/mile calculation? In other words, you can get below rated range on an sr+ even if the trip meter shows 209wh/mile because you started with a cold battery? And that 'consumption' just isn't accounted for?

It can also happen if the battery was particularly cold initially.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
14,206
18,279
San Diego
Hey Alan, so you are saying, a cold battery won't 'count' toward your wh/mile calculation? In other words, you can get below rated range on an sr+ even if the trip meter shows 209wh/mile because you started with a cold battery? And that 'consumption' just isn't accounted for?

Since I live in San Diego, I have never experienced a significantly cold battery, and I don't know exactly how it works. What I have been told is when you have the snowflake, you will have fewer rated miles available (displayed rated miles) - however, they will come back once the battery warms up - they will become available - and the amount is shown with a blue bar section of the battery (but it would be hard to determine what that exact number of unavailable miles is).

So in that case, if you use the "initial minus final" rated miles for the consumption formula, it probably won't work out correctly.

For less extreme cases, I think it is possible for the available energy estimate to change in the battery, even if the snowflake is not present. Haven't really ever experienced this myself, but it seems quite possible.

Again, since I don't live in a cold environment, it's unlikely I'll be able to do anything other than speculate about this or rely on the careful observations of others.
 
I have a long range RWD which was 325 miles when I took delivery in March, 2019. I usually charge to 90% (occasionally 100%) and it was consistently at 292 miles. A couple months ago it dropped to 288 miles and has only shown that since. I did charge to full one time and it was only around 320 (don't remember exactly). I'm sure the capacity degrades over time, but it seems like my range was reduced.
 

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