Exactly.....that was my theory when I had my pusher. The generator was just big enough to keep the smaller batteries charged, and the batteries were big enough to absorb the higher power requirements of hills and acceleration. The smaller batteries provided the power and the genserator extended the range without needing the extra weight of the larger batteries.The idea behind hybrid gas/electrics is to drive the electrical system from batteries, which are being recharged by the generator. The battery has the capacity to provide the high amerage for takeoffs and hills. The generator just needs to provide enough amperage to maintain speed once attained, and recharge the battery with the power needed to get the bike up to speed.
Thus, the gas engine can be smaller than would otherwise be needed, as it can run in it's maximum efficiency RPM range. The battery stores the small excess power until it's needed. A regenerating controller can also convert some of the kinetic energy back into electrical energy when slowing down or going downhill and push it baqck into the battery, so that it's not all lost to heat.