One comment on the issue of the battery bouncing loose from the contacts. This has happened to me. But I also found another cause for having no power all of a sudden when I needed it on a hill..... I had gone more than 5 minutes without using the motor and so it shut itself off!!!

So, now if I'm doing a good bit of flats or downhills without using the motor, I'll just give the throttle a little twist every few minutes.

Also, with regards to comments on my efficient style. Yes, it's different than just going out for fun. I am faced with a dilemma - I need at least some battery power to last the whole way to work - to get up that last hill. So I have no choice - I have to do a lot of the work myself, and pedal. Fear (of running out of power before getting up the last hill) is a great motivator. Also, I like knowing that I am getting exercise. I swear I loose a pound each time I ride the bike round trip to work.