A couple of critical points: If you have a 24 or 36V system, only jump from the battery that has the TM negative lead on it. In the event a jumper is in place to reduce TM interference in the electronics, jumping to another battery will result in shorting one or two batteries and bad things can happen. Also, if you have a TM with a built-in transducer, it would be a good idea to unplug the transducer cable before jumping to keep from blowing the fuse in the head of the TM.