kW equals amps times volts. But yes, if it is sampling these at different times the kW will be off, so the kWh will be also.

Picky, picky- but yes, I should be more precise. Someday I'll get it right the first time...

For those who may be curious about what GJetson means and why it matters...

Yes, kW is an instantaneous value, and the values for volts and amps used by TorquePro to calculate kW are also instantaneous. However, a kWh, the unit used to describe battery capacity, is how many kWs are available over a time period of one hour.

TorquePro records instantaneous values for amps and volts every half-second (the settings can be changed); unfortunately those values for volts and amps are not recorded at the identical half-second. TorquePro multiples those discordant volt and amp values to get instantaneous kW. However, some pairs of volt/amp values could have been recorded as much as 6 seconds apart. An amp times a volt six seconds later is not very meaningful if the power applied changes during those 6 seconds, for example, due to acceleration up a hill, regen braking, or a gust of wind.

I found it interesting that I always received a pretty substantial underestimate of kWh used in TorquePro- on the order of a couple-a-few kWh less compared to what the info screen told me at the end of a long trip. This is almost certainly because during deceleration not as many kWhs are regenerated as the amount of kWhs used during rapid acceleration. It's tough to see more than about 13 or 14 kW on the DIC while regen braking for very long. It is not so tough to see 30 or 60 or more kW over a few seconds or longer when accelerating and/or climbing a steep hill. When driving steadily, there is no bias. Therefore, the largest magnitude of bias occurs when accelerating. Before and during acceleration TorquePro ends up multiplying a large amp, for example, used when accelerating by a too small volt used a few seconds before speeding up. That small volt times the large amp produces an underestimate for kW for the instant that the amp was used. Therefore, the largest bias is that a large amp, say, should have been multiplied by a bigger volt (or vice-versa), leading to an accumulating underestimate of actual kWh used.

To obtain the kWh values on the State of Charge vs. kWh curves of an earlier post, I divided instantaneous kW calculated by TorquePro by 7200 (because there are 7200 half-seconds in one hour) and calculated a running total. Although the exact numbers for kWh used are an underestimate, the arched shape of the curve is almost surely the correct form of the relationship between state of charge and kWh used.

Comparatively, when you're charged-up and use a kWh, it looks like you could go forever. When you use a kWh when low on charge it looks like you'll run out of power yesterday! Therefore, the best estimates of overall capacity are made by subtracting kWh values at intermediate states of charge. The capacity value is more representative when state of charge is between 75% and 25%, or 80% and 30%, than when SoC is between 100%-50%, for example.