Spikes and surges...
A few months ago I did an experiment where I measured battery voltage in hundredths to estimate how much energy I used. First I found that I could climb a certain hill with no motor at 3.5 mph. I recorded voltage and climbed it again, this time rolling on just enough throttle to climb at 7 mph with the same pedal effort. I recorded the voltage.
That low speed was handy because in still air, air drag is insignificant. It's all about the energy to gain altitude. I climbed it again using motor only at 7 mph. I measured the voltage. I'd used just about twice the energy as the time before, meaning that the time before, my legs had supplied half the energy, as I'd intended. A little throttle had saved time and leg energy getting up that hill.
I climbed it again with no pedal power and full throttle, noted the terminal speed, and checked the voltage. Climbing the hill required the same number of joules as at 7 mph, but it also took a lot of joules to accelerate to the higher speed. That was easy to calculate, as was an estimate of air drag joules, which was relatively small. I added it up and found that the loss in battery energy was about 50% greater. I seem to have a 25 amp controller, and opening the throttle to 25 amps greatly reduces the efficiency of converting chemical energy into electrical energy.
I use my half twist-thottle like a cruise control. Because I can feel how far I'm turning it, I may let my speed drop on a hill, rather than demand amperage that's inefficient for the battery. My display reads 195 miles since the last charge, and I'm still 57% charged.