If I Upgrade My Boat’s Charger, Do I Have to Upgrade the Breakers?

Question:

I have a 2001 Four Winns Vista 328. I upgraded my factory installed charger (Guest 15 amp) to a Marinco 30 amp charger. Do I have to upgrade any breakers?  The boat has a 3-bank system (1-house and 2-starting) with (3) lead-acid, group 27, deep cycle batteries.  Thanks, Angela

Answer:

Great question.  Wiring between battery chargers and batteries is generally rated to the output of the charger. For instance, a 15 amp charger will need at least gauge 14 wiring on the DC side, probably gauge 12, with probably 20 amp circuit breakers. Considering that you are doubling the charger output to 30 amps, your DC wiring will need to be a minimum of Gauge 10 wiring, probably gauge 8, and the fusing is probably 40 amps.  Make sure to read the battery charger manual to get all the specifications on the DC wiring and DC fusing. The AC circuit breaker can probably stay the same, as long as it's 10 or 15 amps.