Both are correct. 300 Gid * 80 = 24kWhdm33 wrote:Thanks. That doesn't seem to be what the Android Leaf app is doing. For my car it shows 260 GIDs and 20.8kwh at a recent 100% charge.TickTock wrote:Depends on the app. I integrate V*I*delta_T to compute the kWh during driving for efficiency computations. For remaining energy in the battery, gids remains the best indicator. Multiply by .075 to get kWh.
260*.075 = 19.5 kwh.
I had seen a GID described as 80 watt hours. That if I use 0.08 then it does work out,
260*.080 = 20.8 kwh.
Which value is correct?
Of that 24kWh capacity, 22.48kWh is pumped into the battery, and about 0.48kWh of the 22.48kWh is held in the battery at the bottom of the SOC, leaving 22kWh pumped in the battery that is "available" to use. Unfortunately, there are losses not accounted for with the 80 kWh calculation when you pull the energy out.
The usable value is closer to 75 per Gid, not 80. Actually, for that brand new battery with 21.3kWh usable at room temperature, it is about 77.45 per Gid.
A fully charged battery at 281 Gid, minus the 6-ish Gid remaining at Turtle leaves 275 Gid used multiplied by 77.45 per Gid = 21.3kWh (actually measured in a government test at room temperature). So, I just want to be clear that there are temperature related adjustments to capacity. We see Nissan's programming for these adjustments in the winter as the Gid count actually goes UP, even though the battery capacity goes down with cold.
LEAF battery capacities
Energy from the wall from dead to 100%: 25.414 kWh
Energy from the onboard charger to battery: 22.031 kWh (86.6% charger efficiency)
Energy from the battery during discharge: 21.381 kWh (our generic "21kWh" useable at 70F)
http://www1.eere.energy.gov/vehiclesand ... 2012_o.pdf" onclick="window.open(this.href);return false;
http://www1.eere.energy.gov/vehiclesand ... 2012_p.pdf" onclick="window.open(this.href);return false;
New 70F/20C fully charged battery
12 Fuel bars segments showing
Rated capacity: --24 ------- 300 ---- 100
Max possible. : ---24 ------ 300 ----- 100
Stored energy: --22.5 ----- 281 ----- 95 (4.1v per cell, 393.5 volts)
Usable energy: --21.0 ----- 281 ----- 95 (4.1v per cell, 393.5 volts)
Depleted cutoff: --0.5 ------ 6 -------- 2 (zero fuel bars remaining, 300v)
The battery temperature correction factors that I use are actually used in the LEAF Spy app for the DTE data. The app also uses the 0.48kWh stored at the bottom of the charge for DTE calculations, instead of counting GIDs to zero for range (which it obviously will never reach).
The battery temperature formula is 1% loss per 4F degrees below 70F and gains 1% per 8F above 70F.
Therefore, 281 GIDs at 30F battery temperature will have about 19kWh of usable energy, which is 69 watts per Gid. So, 75 is as good as any singular value, but obviously it needs adjustments for temperature, and the wattHour value per Gid can vary significantly.