This may just be the way battery tech works. I think the readout on my new bike (it's in the shop being assembled) only shows four levels of charge anyway, which is good for me, because I'd get very worked up trying to figure out why it dropped 5 percent in this situation and only 3 percent in that one.
On one blog I found somewhere, some engineer was raving about pretty significant passive battery drain when batteries are turned on even when the motor is not in use. He recommended shutting the battery off completely when you're on a long downhill-- or even stuck at a traffic light, which seems crazy!
When I hypermile my Trek 920/Clean Republic Hilltopper front hub conversion, I do shut the battery off completely during one long downhill stretch and on another long flat stretch. Hard to say, because I have no meter or display of any kind on the bike, it's a bare-bones 250W conversion with a tiny 5.4 Wa battery, but I do think I get better range by shutting off the battery when I'm not using it-- I can get 16 miles out of a 12-mile battery instead of 14 or 15, and that includes over 1,200 feet of vertical.
But I'm kind of OCD with hypermiling just in general. My second car is a 1991 Honda CRX that still gets 49 MPG even on runs when I might hit 90 MPH while passing... it loves to cruise at about 79-81 MPH, and if I can maintain a steady speed, I can still get nearly 50 MPG. I like to bike the same way-- high top speeds occasionally, but the most efficient cruising I possibly can.
