[hemiblas]

You guys all make some good points, but I see a fexibility in this system that might be useful. Right now I have differenent battery configurations and I usually buy a battery per vehicle or plane. Then the lipos might sit for a while before it gets some use. Sometimes they puff and I have to take apart the packs and rebuild them which is a pain and I have to come up with a new plan to get a higher voltage pack

Here if an individual cell puffs, then you just throw out the cell.

I'm not so sure mixing old and new cells is a bad idea. There is so much variance between cells that a cell thats been run 40 times might be in the same condition as a cell you just bought that wasnt quite right. Even new cells dont discharge at exactly the same rate.

Couldnt the same be done by just selling single cells with a separate connector on each one and then using series or parallel connectors to get the same result? That might be a better idea. You can charge the cells separately so you each cells charges to its maximum, no risk of missed connections. You could buy some heavy duty discharge batteries that would work in all your applications from large to small.