It is pretty easy to explain: three batteries, A, B and C. Each has a positive (+) and negative (-) post. outboard cables: Red to A+, black to A-. troller: Red to A+, black to C-, jumpers from A- to B+, B- to C+. Dont forget that the jumpers ought to be the same size wiring as the main wiring for the troller. They will carry a lot of amps, although fortunately they will be very short. One other note on the topic, one weak/bad battery will cause problems. An old battery develops high internal resistance, and act as a current “restrictor” since this is a series circuit. Im not so hot on replacing a single battery in these series setups. Ive had too many problems in the past. I only run 24v at present, and replace both as a set (I run a MG troller and rewired the 12v/24v switch to be “24v and constant-on” since I never use 12v setting anywhere… with a good triple-bank charger where the three sections are truly independent, you connect each section to the corresponding battery, section 1 to A+, A_, section 2 to B+, B-, and section 3 to C+, C-. Note that some old triple-bank chargers would go up in smoke wired like that as they were not independent and you end up with internal charger shorts because of the inter-battery jumpers. I had one of those 15 years ago and had to remove the jumper. My boat actually did the “jumper” thru a switch that had to be in “charge” position to charge, which isolated the two batteries by eliminating the “jumper” connection in the switch. Flipping it to “run” connected the jumper to get 24v. I dumped all that in preference of pure 24v.2008 Pantera Classic2014 Mercury Pro XS 200
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