basic wiring questions

[dr.livingston]

I just bought a used boat with a Force 120 on it. The previous owner apparently did some midnight engineering on it and so I have some questions about restoring full functionality.

Originally it apparently had two batteries and a manual selector switch. He removed one battery and the selector switch and moved the other battery to make room for more fuel tanks.

Question 1. Is the second battery simply a spare in case the first one dies, or is the second battery a "house" battery that runs lights and accessories while the first battery cranks the engine?

Question 2. Does the engine charge these batteries while running, or do I have to use a separate charger to keep them up?

Question 3. Neither the tach nor the speed gauge works although the volt meter does work when I turn the ignition key. Did he disable them by removing that second battery? He also removed the fish finder and the marine radio so maybe he left the gauges disconnected while he was fooling around behind the instrument panel.

 

[Frank Acampora]

Re: basic wiring questions

I have a buddy with a 115 Rude like that. He needs to work four switches to start it: Main disconnect, ignition, choke, and starter. A real hassle, ripe for error, and the wiring behind the dash looks like a spiderweb.

Anyway, there's no way of me knowing how the second battery in your boat was wired. It may have been used for all other functions except starting or it may not.

However: You should really have a six terminal ignition switch either in the control box or in the dash. With this switch, green wire attaches to "C" or choke terminal and you push in on the key to choke, yellow attaches to "S" or start, and the white and blue wires each attach to one of the two "M" terminals. --Separate wires on separate terminals, not both on the same one.

Power to the tach and other instruments should come from the "I" terminal. This terminal only has power when the switch is in the run or start position. Signal to the tach comes from the purple wire.

Typically, the second battery is used to power a trolling motor. The switch can be set to either one or both batteries so the engine can charge both while running. However, these alternators do not deliver a lot of amps and charging a dead trolling battery is very ineffient. They were designed to replace power used in starting the engine and only a little more. Typically they deliver around 7 amps. The small red wire from the circuit breaker (black plastic box on bottom of engine terminal board) to the start solenoid connects the engine charging system to the battery through the battery cables and the engine will automatically re-charge the starting battery while running.

If you decide to re-install a second battery, be certain you buy or have a switch with a separate alternator fields function since disconnecting the alternator while switching batteries can harm a few electrical components.

 

[RRitt]

Re: basic wiring questions

i live in a saltwater boating community. Almost everyone has two batteries and a manual selector. Around here, the purpose is so that you never get stuck on the gulf with an engine that won't start and a radio that can't call the coast guard.