Charging issue

[Rated Aargh]

Took a 34 chb for a very extended sea trial this weekend possibly purchasing from a friend
We went 6 hours east spent the night and about 7 hours back west the following day.
After about 2 hours I noticed the volt gauge had dropped to 12v. The current owner flipped a few switches and voltage came back up to 13.6v while motoring. About an hour later the voltage dropped again. He went back and flipped some different stuff or what ever and nothing changed. I started looking around and turned the original selector switch from both to battery 1 and back to both. The voltage went back up. An hour later same issue with voltage drop so switched the battery selector from both to 1 and back. Voltage came back up. So I figured out how to correct the problem temporarily but it’s not a “fix”
I accessed the panel to see what the switch was actually doing and became even more confused because that battery selector switch was unlike anything I’ve ever seen lots of wires and connections on it but nothing bigger than 10ga maybe so it’s got to be feeding relays somewhere to switch the full battery loads.
There is two alternators on the engine both were charging at 13.6-13.9 while running by the time we got to the lake it was far too rough to go into engine bay while underway so I was unable to test alternators when volt gage dropped.

Any one ever experience this issue or have any ideas?

 

[O C Diver]

If you have 2 alternators, it would be important to understand how the control circuit is wired. Generally when the batteries are full, one alternator regulator may be turning off. Flipping the switches may remove power to the regulator and then restore it, resetting the regulator. Is there a Center Fielder that's controlling the regulators? Do the alternators have external regulators?

Ted

 

[Rated Aargh]

The alternators do have external regulators on them but I have no clue how they are wired for the charge circuit.
It’s not my boat yet so I don’t know much about the details other than quick visual observations.
But I will admit the original chb battery selector switch is something I’ve net seen the likes of before. I wish I would have taken a picture of it.

 

[High Wire]

Custom installation so we’re all going to be guessing. Should be fixable. Switching battery switches while engine running is usually bad for alternators. Zap Stop, field disconnect, or direct wired to a battery through a fuse will prevent the diodes from blowing on a switch position change.

 

[O C Diver]

It's hard to offer more advice without a better explanation of the control wiring of the regulators. It seems like the alternators work, but whoever added the second alternator didn't necessarily add the correct control circuit.

Ted

 

[sunchaser]

The alternators and charging circuit can easily be assessed by a marine electrician. Fixes if needed shouldn’t be too expensive.

The bigger question is are you going to have a complete marine survey, out of the water exam and sea trial? Friend or not a good independent evaluation will save a lot of potential headaches.