An electrical connector includes a middle board, a first insulative housing defining a first receiving room, a second insulative housing defining a second receiving room, and a number of contacts mounted on the first insulative housing. The method can also include producing, in at least one second working step, a final thread having a final thread profile, which has two final thread flanks and a final thread root connecting the two final thread flanks. A computer controller with a self-contained LED display screen allows for onboard diagnostics and changing of operating parameters without the need for a laptop computer or other externally connected devices. An engine supporting bolt is made to penetrate through the vehicle body side bracket, the left and right engine-side brackets and the left and right auxiliary brackets, whereby the brackets are connected to each other. In one example, flyback transformers supply charge to lower capacity battery cells to extend battery output.