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Teslafi - under-reporting consumption vs car display

pdk42

Active Member
Jul 17, 2019
1,108
1,097
Leamington
I've noticed that Teslafi consistently under-reports consumption compared to what's displayed on the car's odo. For example, a 45 mile drive today was reported by Teslafi at 213Wh/mile, whereas the car showed 255Wh/mile. Anyone else getting this? I guess I'll need to do some calculations based on closer inspection of the charge state, miles driven etc to see which is right.
 

LukeT

Member
Apr 9, 2019
729
337
UK
I haven't checked this myself, but might it be teslafi measuring consumption of that "drive" alone vas the car measuring all consumption since a defined start point in time (so including some consumption before or after a teslafi defined "drive")?
 

pdk42

Active Member
Jul 17, 2019
1,108
1,097
Leamington
I haven't checked this myself, but might it be teslafi measuring consumption of that "drive" alone vas the car measuring all consumption since a defined start point in time (so including some consumption before or after a teslafi defined "drive")?
I guess that would be a plausible explanation. Need to look at it more closely.
 

DJP31

Active Member
Aug 30, 2015
1,686
1,092
UK
I've noticed that Teslafi consistently under-reports consumption compared to what's displayed on the car's odo. For example, a 45 mile drive today was reported by Teslafi at 213Wh/mile, whereas the car showed 255Wh/mile. Anyone else getting this? I guess I'll need to do some calculations based on closer inspection of the charge state, miles driven etc to see which is right.

if you look in the TeslaFi vehicle settings you can adjust the kWh Wh/m factor so TeslaFi matches the car.
 

Jason71

Active Member
May 8, 2019
3,044
3,049
Shropshire
I have had a look at a raw sample of tesla API data ( don't have a car so cannot look at the real thing yet) and the car does not report any data like watts per mile directly so Teslafi must be deriving it. The odometer data is reported as is the current battery level
you could calculate it from these 2 figures but only if you know what the size of the battery is or at least what 100% actually represents. So it could be that the car and teslafi are using slightly different figures for the battery size so 1% battery loss represents a different amount of energy in each calculation
That would be my guess. this is may be what the adjustment factors that DJP31 mentioned allow you to correct for
 
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VanillaAir_UK

Well-Known Member
Jun 17, 2019
8,408
5,939
Surrey, UK
We have a very slight discrepancy but put it down to how TeslaFi calculates the value vs how car would and have nearly always been as within rounding levels of accuracy of battery level. As above, TeslaFi needs to derive some figures from drive start/end values of battery and odometer. The only major discrepancies I have seen is when TeslaFi missed the start of the journey so only measured part of the journey - easy to spot from the GPS maps - from the logs, it did seem right from that point though, but missed the initial higher power warm up.
 

DJP31

Active Member
Aug 30, 2015
1,686
1,092
UK
The only major discrepancies I have seen is when TeslaFi missed the start of the journey so only measured part of the journey - easy to spot from the GPS maps - from the logs, it did seem right from that point though, but missed the initial higher power warm up

That’s a fairly new behaviour and generally happens when TeslaFi stops polling the car in a sleep attempt.

Historically the car stopped reporting the outside/inside temperatures when it was preparing to sleep, and TeslaFi stopped polling at about the same time. Something changed in one of the updates and now the car continues to report the temperatures, many of us noticing that the car suddenly wasn’t sleeping - because TeslaFi was continuing to poll. TeslaFi will now (depending on settings) stop polling periodically but if you happen to drive during this time it won’t log that data until the sleep attempt finishes.
 
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