BigBendFishing.Net

I have a used boat with two batteries in parallel. For the past six months I have taken the boat out at least twice per month. Every time I would go out on battery #1 and operate all the electronics with #1, and when it was time to return to dock I would switch to battery #2. Everything was going fine.
Two trips ago when it was time to return I switched to battery #2 and nothing worked. The motor wouldn’t start, the radio wouldn’t work, the GPS/sonar would not work. I switched back to battery #1 and returned to dock. When I got home I tested both batteries and they both registered 12.8 volts. And...curiously...when I tested the electronics everything worked fine on either battery #1 or #2!
I went out again last week. When I put the boat in the water and turned the Perko to battery #1 nothing worked. I switched to #2 and everything worked fine. I took a chance and went fishing anyway and did not have any problems operating on only one battery. Actually, the AM/FM radio doesn’t turn on when battery #2 is being used.
Is it unusual for a Perko switch to go bad on one side? How do I confirm the Perko is the problem and not something else?”

Ohm meter. Test continuity, with the battery wires disconnected, from main input contact to either of the switched contacts and operate the switch. Then go to the other switched contact and repeat.

I attempted to disconnect the batteries so I could perform the continuity test. As soon as I put the socket wrench on the negative terminal for battery #2 I discovered that the nut was loose. I tightened the nut, and throughly checked all the other connections, put the Perko in position two and the engine cranked right up! And, all the electronics work. I found a blown fuse which caused the AM/FM radio stop working. Anyway, I have learned my lesson and will pay more attention to routine maintenance.

Glad you got it fixed. I like the Blue Sea switches, but they'll go bad sometimes, too.

FYI, if you have wing nuts on your batteries I'd recommend replacing them with stainless steel nuts and lock washers. Wing nuts are another possible bad connection spot and fire hazard.