10-03-2017, 12:13 PM
Most people on boats underestimate 12 volt battery banks. The currents that flow in a valve radio are really minute. Likewise the wattages are low. Currents in an engine circuit are huge. You need 300 amp cable and 100 amp cable. Wattages are up to 3 killowatts. Soon I have to finish my alternator charging system and may use a relay. Automotive relays aren't normally adequate. I've heard cases of under-rated relays catching fire. For example, a heavy load on an inverter on engine start with the domestic batteries low. So the risk of shock is low but the currents are high, more so with large banks.
