12 Volt Nightmare

[reelman19]

All of a sudden battery problems; dual batteries, Guest battery switch, batteries installed 6-2014; switch turned to "1" nothing 12 volt works and engine won't crank; on 2 or "both" lights, blower ect work but not enough to crank engine. Replaced battery switch; no change; check all fuses; batteries checked with volt meter and load tester; all checked out.
Frustrating; any input would be appreciated. __________________

 

[gm280]

:welcome: to iboats reelman, good to have you join us...

Well you stated that you installed a new switch and the batteries were load tested, you didn't say if you removed and cleaned the wire/cables going to the starter solenoid and ground at the engine. Too, many times corroded terminals are the cause and once cleaned to shiny metal and retightened things work again. I would certainly check every electrical connection and clean and retighten them before doing any thing else. And even if you can read 12 volts across any connection, they still can be corroded and therefore not pass the proper amount of cranking current. So clean the connections and see what happens. And that goes for any other electrical connection as well. It is a boat after all and they see a lot of moisture and little maintenance as a rile of thumb...

 

[reelman19]

Thanks gm280 will try connections @ starter and ground

 

[Silvertip]

If this happened all of a sudden and replacing the switch didn't solve the issue, yet some of the "low current draw" items work then that all points to a cable problem. You need to make sure the battery cable that ties together the NEGATIVE terminal of both batteries is clean and tight. If that cable is loose or corroded on either or both ends, the system simply cannot work. The same applies to the NEGATIVE cable that runs from one of the batteries to the engine block. You cannot check cable ends by wiggling and looking at them. Remove, make them shiny bright and tighten securely. Battery switches rarely pose a problem.

 

[bruceb58]

+1 on what Silvertip says. This points the your ground connection between your battery and the engine block. Also need to check the ground connection form the block up to your helm fuse box.