Have you tried
this calculator? This one is more specific to a given set up but will still only average out the power per run.
By the time your finger gets to full throttle, the motor is already building up revs. So my guess is the peak draw on the system is in the first 0.2-0.5 seconds. Data loggers sample every 0.2 sec don't they?
Just realized the data logger thing I said
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