That circuit board device is the connector board for a number of different balancing connectors(one type on it is the Align(?) connector that MC & several others use on their batteries & the others are Thunder Power's own balance connector, both for handling 2-6 cell packs). you just plug the pack's balance connector to the appropriate one on that board(as well as the main charge leads to the main wires from the battery) & then start it up....