[Nerys]

Exactly. Two completely independent system. To the ice it would be like I am suddenly going downhill or something so I could "let off" the gas a bit as the E motor took up some of the drain.

When I get home or get to work I "plug in" to recharge the batteries.

as for offset draining. No I would always be using "all" of the batteries just in different variations of parallel and series connections.

For example lets say I have 6 batteries. Thats 72v. if there 6 in series. what if I do 2 sets of 3 in series and run those sets parallel. Now I have a 36v pack with twice the amps IE still using ALL the batteries IE still evenly discharging them.

I do not care if I only get a 10mpg boost. I do not care if I get NO mpg boost. the ideal is to see if it WORKS at all at a price that can fit in my nearly non existent budget. Thats why It has to be dead simple I can NOT afford a "controller". as soon as one becomes mandatory this project becomes a non starter. I just do not have the cash. If I had that kind of cash lying around I would not be so concerned about fuel economy :-)

If it works at all then the idea has merit THEN I can safely spend some serious cash to making it work well. 3-4 hundred dollars I can afford on a "seat of the pants test" 3 grand I can not.