Battery pack with interchangeable circuit substrates

A battery pack, comprising:

• a plurality of battery cells, the battery cells including positive electrode terminals and negative electrode terminals;
• a first substrate and a second substrate, the first substrate and second substrate being selectively coupleable to the positive electrode terminals and the negative electrode terminals of the plurality of battery cells, wherein:
• the first substrate includes a first circuit for connecting the positive electrode terminals and the negative electrode terminals to selectably connect the plurality of battery cells together in a first manner, and
• the second substrate includes a second circuit for selectably electrically connecting the plurality of battery cells in a second manner different from the first manner, and
• a transport medium for selectively attaching and detaching the first substrate or the second substrate to and from the plurality of battery cells to couple and uncouple the first substrate or the second substrate to the positive electrode terminals and the negative electrode terminals.