1977 37 ft Sedan Bridge - Electrical fault

[alps]

New poster here, thanks for accepting me into the forum .

We have a 77 Marinette Sedan Bridge with two gas engines. Recently an electrical fault developed where, after switching the ignition keys on, only the starboard starter will come on when engaging the ignition switch, with the port starter switch not engaging at all. At the same time, the blower, radio, and other electronics are no longer getting power. For some reason, all these things will receive power when we depress an unlabeled push button on the helm, though this push button previously didn't appear to do anything that we knew of (we've only used our boat for enjoying the marina, unfortunately). The push button has to be held in though, so it doesn't work for running the blower or anything else for that matter.

Any ideas what could have gone wrong? It appears to be an electrical fault. It showed up after I'd left the ignition keys switched on for a few days by accident, it may have rained during that time. I've checked fuses and breakers and nothing appears off that I can tell.

[GB49]

The push button is the parallel switch. It uses both batteries to crank each engine.

You mentioned momentarily running the blower etc while holding that switch in.....have you tried cranking the port engine while pushing in that parallel switch?

Have you checked battery voltage for all batteries?

[alps]

The push button is the parallel switch. It uses both batteries to crank each engine.

You mentioned momentarily running the blower etc while holding that switch in.....have you tried cranking the port engine while pushing in that parallel switch?

Have you checked battery voltage for all batteries?

Yes, with the parallel switch pushed in both engines crank as they should, the blower comes on, the radio comes on, etc. A number of other things appear to have been affected, including the water system, the automatic running of the aft bilge pump (still runs manually), some interior lights, etc. Hard to check what else comes back on with the parallel switch push button, though, doing things solo. I have not checked the battery voltage.

Thanks for explaining the function of the switch! Would it be harmful for the switch to stay pushed in - long enough to run the blower before starting the engines?

EDIT: I had misremembered, it's the port engine that is unaffected, and the starboard that is affected with everything else (and that works with the parallel switch).

[GB49]

The parallel switch is designed for momentary use only for cranking engines.

If pushing the switch makes everything work, then you most likely have a bad/dead battery.

Do you have an onboard battery charger? It should give voltage/current charge for each battery or LED indicator to show the state of each battery?

Or put a digital multi-meter on each battery and check voltage. Ideal check is to use a load tester on each battery and verify the cranking Amps.

[alps]

The parallel switch is designed for momentary use only for cranking engines.
If pushing the switch makes everything work, then you most likely have a bad/dead battery.
Do you have an onboard battery charger? It should give voltage/current charge for each battery or LED indicator to show the state of each battery?
Or put a digital multi-meter on each battery and check voltage. Ideal check is to use a load tester on each battery and verify the cranking Amps.

I believe we do have an onboard battery charger... I'll have to go back down and look and bring my multi-meter. She stays plugged into shore power in the slip.

In the engine bay, there are two large rotating switches mounted on the forward support of the engine bay access hatch, with smaller toggle switches on either side. The starboard switch had been switched off for some reason. Could this be a factor here?

[alps]

UPDATE: Tested the batteries, all good except the starboard read 0! So you were right, the battery was the problem. It must have drained when I left the ignition on? Can't understand why it affects all the other things and why the port side would be fine, unless that switch in the engine bay is related to the charger.

I'll have to get into the storage area behind the galley stairs to see what's going on with the charger (I think I saw it down there awhile back).

Wonder if a trickle charger could be plugged into the wall outlets to charge the battery? The batteries are 2 years old.

[GB49]

The rotating switches in the engineroom (usually red & black in color) should be the battery switches and will prevent equipment and engines from powering on. You generally want them all on unless one of them is a combination switch that can combine more than 1 battery for an extended period of time.

The battery charger and bilge pumps should be on the hot side of the switches. No matter if those rotating switches are ON or OFF, the pumps and charger should still function. **This assumes the previous owner wired things correctly**

A trickle charger probably wont bring back a battery that shows 0V at the terminals. I would hedge a bet that battery is beyond repair if it has been sitting at 0V for a while. Curious what brought it all the way down. Usually a dead battery will have a few volts but not 0 unless something is actively pulling it down.

[Fastjeff]

.."Wonder if a trickle charger could be plugged into the wall outlets to charge the battery?"

Look out for these things for they can over-charge and destroy a battery. What you want is a float charger that shuts off when the battery is topped off.

Jeff

PS: When so many electrical problems happen, I first look to a bad ground situation.

[GB49]

Jeff makes some good points about electrical issues.

Also keep in mind if you are trying to charge a really dead battery be sure all the cells are full of water and be extra aware of gassing that may occur during charging. It might be a better idea to remove the battery from the engine room and charge it in a well ventilated area so not to collect the hydrogen sulfide gas in the bilge.

[alps]

Thanks Jeff and GB49, really appreciate it. Good points about the trickle chargers and to watch for gassing and potentially remove for charging. Need to investigate the battery charging system a bit more and go through the grounds as Jeff suggested.

The starboard "battery switch" had been switched off for some reason, at the same time that the ignition keys were left on. Can't remember what else may have been left on or not.

Now that I have a wiring diagram to reference that will help a lot. Once I sort the battery issue we'll see if that helps the other issues.