It is in fact all wasted when something goes wrong with the hokey Chinese charger, and you brick your battery pack. Just to be clear.
If I were you, I would use a motorbike of some kind rather than a bicycle. If you feel you must use a bicycle, find an out-of-date freestyle bike from the days of 40-50 pound freestyle bikes. It won't offer you a lot of space for equipment, but it will probably not twist or break when you run a golf cart's worth of motor torque through it.
And I would plan on not using the cranks. The motor drive will prevent them from turning.