Wiring Diagram with 4 6v golf cart batteries and starting battery on Luna Loca

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Luna Loca

Basic Design

Given that I know we are energy hogs that do a poor job of conserving batteries I went with a system that is large enough to get me through a day of sailing and a night at anchor without charging; normally staying above 50% discharge. It was also important to me to have a totally separate starting circuit. Losing the Autopilot, chart plotter, radar due to low voltage caused by starting the engine is not good for the electronics and scares/confuses the hell out of any guests that may be driving the boat. Normal switch positions. Main battery switch is in 1. Start battery switch is “on”.


House: 4- 6v golf cart in battery locker under settee in front of galley sink.

Start: 1 -12v (Group 24?) Mounted under aft bunk, in prop shaft access space.


Xantrax True Charge 20 (yellow unit) mounted under Navsta desk. Separate charge circuits to each battery bank protected with circuit breakers. Powered by shore power or Honda 2000.

Engine. OEM 55 amp internal regulated alternator wired to house bank. Start battery charged through a Blue Sea Systems Starting Isolation (SI) Dual Sensing Automatic Charging Relay. When wiring the alternator directly to the house bank, ensure you also move the sense wire (orange) to the house bank. It is normally connected to the + terminal on the starter as was the alt output before it was moved.


XANTREX LinkLITE mounted under cabinet (with sliding doors) above electrical panel.

Battery Cables

Existing cables if reused had connections replaced. Crimped, Soldered, Sealed.

Positive cables. House Bank to Battery switch position 1. Start battery has new On/Off switch located on engine bulkhead in aft cabin. Wired direct from switch to starter, then to Battery switch position 2 for emergency use.

Negative cables. House bank to engine. Start battery to engine. House loads from panel to engine and to house battery bank neg bus.

Used existing cable runs when possible. New cables go under cabin sole, under the head sink then between muffler and engine bulkhead to rear of engine. Straighten two wire coat hangers and taped together to snake cables under the sole.

If following my diagram, if you want to monitor the house battery charging with the cockpit voltmeter it will be necessary to move the engine panel 12v feed (red wire) to the house bank. It is currently attached to the + starter post and will read start battery voltage.

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