Miles per KWH - is it accurate?

I've been checking my miles per KWH lately and started wondering if the Nissan dash value wasn't off. I decided to check using the GIDs values from LeafSpy. I recorded the starting value, the ending value, and miles driven. Multiplied the GIDs used by .0785 to get KWH and divided mileage by KWH to get miles/KWH. My dash reads 3.7 to 3.8/KWH pretty regularly but the calculated value is several tenth's lower. I've done this several times now with similar results each time. I've always thought that the Nissan numbers seemed a little high compared to what I was actually seeing in terms of mileage. Has anyone else checked their miles/KWH this way? I'm curious if this is a common problem or just a quirk of my driving habits.

The default in Leaf Spy IIRC is 77.5 watt-hours per gid. Whether or not that's actually correct at all, esp. over the entire range of the battery is ummm...questionable.

See https://mynissanleaf.com/viewtopic.php?p=562501#p562501 and the posts I linked to.

Doesn't sound like you're accounting for energy derived from regeneration. Back when I used to log onto Carwings to checks stats, regen fairly consistently contributed about 10% of the overall power consumed.

For long drives I depend on the dash miles per kWh.
It feels spot in for me when calculating back to what LeafSpy says I have left, if not slightly low. When I was driving back through rain from Iowa city, I ended with 3.9 efficiency for the 220 or so miles. With 58 kW usable I should only have about 226 mile range. I ended with over 5 kW left, which is about 20 miles or 240 total possible. Now with only 1 decimal precision it could be 3.94 or...3.99 depending on how it shows up. At 3.99 we would be pretty right on.

cwerdna said:

The default in Leaf Spy IIRC is 77.5 watt-hours per gid. Whether or not that's actually correct at all, esp. over the entire range of the battery is ummm...questionable.

See https://mynissanleaf.com/viewtopic.php?p=562501#p562501 and the posts I linked to.

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I used .0785 because that was the best fit for the spreadsheet I use where I track my degradation. It compares GID's reported to AH reported by LeafSpy. I used the nominal battery voltage x the amp hours reported x a constant to calculate GID's. I got the best agreement with observations with 78.5w/GID. YMMV.

Nubo said:

Doesn't sound like you're accounting for energy derived from regeneration. Back when I used to log onto Carwings to checks stats, regen fairly consistently contributed about 10% of the overall power consumed.

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Since I used starting and ending values from LeafSpy, regen would have been rolled in. It's possible that Nissan's dash calculation doesn't consider regeneration which would push it's numbers higher but I have no idea how Nissan calculates it. That's part of the question here.

DougWantsALeaf said:

For long drives I depend on the dash miles per kWh.
It feels spot in for me when calculating back to what LeafSpy says I have left, if not slightly low. When I was driving back through rain from Iowa city, I ended with 3.9 efficiency for the 220 or so miles. With 58 kW usable I should only have about 226 mile range. I ended with over 5 kW left, which is about 20 miles or 240 total possible. Now with only 1 decimal precision it could be 3.94 or...3.99 depending on how it shows up. At 3.99 we would be pretty right on.

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If you covered 220 miles with 53 KWH then you averaged 4.15m/KWH not 3.9. Even at 4.0m/KWH you would have had only about 3 KWH left. Your dash read low, mine seems to read high. Could be just the difference between a '16 and a '19 model with different size packs. I'm just curious about the accuracy of the gauge.

I will try to do some screen shots in my next long drive and google drive them so I can share.

Leftie, if I become a premium member, can I upload photos?

Leftie, if I become a premium member, can I upload photos?

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I honestly don't know. I think you can add a photo to your posting ID, but I don't know if the posting photo upload feature still works.

my suspicion is that M/KWH meter on the 2019 S does not account for electricity used to heat the cabin- traction motor pretty accurate I think but I get bigger differences in actual miles depending on how cold it is outside.

Look, this easy enough to do if you have LeafSpy. Note your starting Gid's value, reset the trip meter and reset the mi/KWH meter. Drive the car for a while and note the current Gid's value, mi. driven, and the Mi/KWH value. Subtract the current Gid's value from the starting value and multiply the result by the KWH constant per gid. That gives you the number of KWH used. Divide the miles driven by the number of KWH calculated to get mi/KWH. Compare that to the dash gauge.

When I do this, the value I get is consistently a couple of tenth's lower than the dash gauge. What I'm curious about is what other people are seeing.

johnlocke said:

Look, this easy enough to do if you have LeafSpy. Note your starting Gid's value, reset the trip meter and reset the mi/KWH meter. Drive the car for a while and note the current Gid's value, mi. driven, and the Mi/KWH value. Subtract the current Gid's value from the starting value and multiply the result by the KWH constant per gid. That gives you the number of KWH used. Divide the miles driven by the number of KWH calculated to get mi/KWH. Compare that to the dash gauge.

When I do this, the value I get is consistently a couple of tenth's lower than the dash gauge. What I'm curious about is what other people are seeing.

Click to expand...

Gid's are not accurate measurements of energy. You do know that the "kWh constant per Gid" isn't constant, correct? Get an EVSE that measures kWh to a reasonable accuracy. Remember to multiply by the charging efficiency.

I’m no expert by any stretch, but I’m pretty sure the “miles/kwh” on the dash is not really all that accurate, and I tend to ignore it.

For example, I’ve a 2021 leaf with standard 40kwh battery (I know it’ll be more like 37kwh usable). On today’s drive I did 28.4 miles, I used 29%, and the dash said 3.8 miles/kwh. So, on my calculations (100x28.4) / (29x3.8), indicates that the car has an effective battery capacity of 25.8kwh. Thats clearly wrong. The car has full 12 bars, so it can’t have lost around 10kwh. Although the temperature was a mere 3°C and heater was on (intermittently)

As I say I’m no expert but reasonably good with maths and at least 2 of those data figures above are correct (the % used, and the miles done), leaving the miles/kwh in doubt.

Hope that makes sense,
Andy.