Nice bike-what is your total battery weight?
Your battery is roughly 1000 watt-hrs, right(12X80=960 watt-hrs). I'm guessing roughly 50 lbs?
A Prius battery pack is 1500 watt-hrs and is supposed to weigh 90 lbs-I'm guessing your pack is roughly the same energy/wt if it is nickle metal hydride.If it is lithium based, it could be 30 lbs or so,I think.
Indelicate question-HOW MUCH??
It is like an old fashioned moped-you can still pedal it?
How far down can you draw those batteries(70 % charged like a hybrid car)?
What sort of range-all electric-at 15-20 mph level hy?