Last week I did a 120 mile ride on my ebike, which included about 700 metres of climbing. It took around 11 hours: 8 hours on the bike at 15 mph average, 2 hours in cafes recharging myself and the battery, and one hour for camera stops and general faffing. I wasn't riding particularly hard (I'm not fit enough), and used a bit less than 9 watt hours per mile. I'm estimating my own contribution was about 4 watt hours per mile and so the electric system is around 60% efficient - 3 watt hours at the wheel take five watt hours from the battery.
At that level of effort I feel as if I could go on forever, though of course I want to increase my fitness and be able to do the same trip with less assistance. Even four watt hours per mile or less is nice to have, to push you over the points that would otherwise slow you down and force you to accelerate yet again at the end of a long day.
But for now I'm just curious - just how much does my battery eat? My typical cafe stop puts about 300 watt hours into the battery, or 258 kcal. Given the difference in conversion efficiency (4 kcal of food energy to 1 kcal of output) each watt hour is "worth" just over 2 kcal.
So 300 wh is equivalent to [roots through larder - quick calculation] just over half a pot of raspberry jam?