Wire it to an open slot in the fuse block if you want to free up you OBDII connector--#46 is an always on (not just on with ACC) slot that you can use. As for trickle charging the battery while it's still hooked up to the vehicle, I know others who have done that with their CR-Z, but I've always disconnected the pos. and neg. terminals to charge the battery--but I can't say for a fact that it's absolutely necessary to disconnect them.