Power drop to 270 helm area

[Hoplite808]

On my 1996 270 Sundancer I’m experiencing a significant power drop to everything at the helm station.

It started with the vhf loosing power when I’d try to transmit. So I thought it was just that poorly wired. I fixed that but during testing after I found that the more I turned on at the helm the lower the voltage for everything would get. With the blower, nav lights, bilge lights, deck lights and water pump on the supply voltage dropped to 9vdc at the helm. Which of course is insufficient for the ignition to work well and will cause the vhf radio and chart plotter to shut down due to insufficient voltage. However testing at the breaker and the battery there was no voltage drop at all.

I’m assuming there is a buss bar somewhere here that’s likely become corroded and the that’s what is causing the voltage drop. But I can’t seem to find it. I’m thinking of just running a new power wire to the helm unless someone here has had a similar issue and could perhaps tell me where the buss bar is hidden or if they have had a similar issue how they fixed it properly.

 

[Stee6043]

I'd bet weak batteries before wiring or connections. Have you tested your batteries under load? You can take them to an auto parts store and have them tested for free.

Otherwise you can buy a tester for small money, go DIY on 'em:
https://www.amazon.com/gp/product/B000AMBOI0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Lazy Daze]

After verifying your batteries are good...

Verify the main power lead is tight and in good condition. You'll be looking for a wire that is about a 10g. It will originate from your battery switch. The other end will go to a DC breaker panel. It may or may not feed a secondary breaker panel. But from there I think you're find a wiring harness that feeds the dash. In other words, I don't think you're going to find the main feed wire behind the dash.

 

[Hoplite808]

The batteries are newish and test fine. There is no voltage drop at the batteries or the main breaker box. The voltage drop only occurs at the helm station and seems to be from the main feed.

If I understand the wiring schematic correctly the battery positive goes to the selector switch then the main breaker box in the engine compartment. It then branches to several items that are then their own sets of circuits. The helm station is one of those circuits that a main feed enters the secondary breaker set for the 12v systems and also feeds the ignition switch and anything plugged into the switches (EG: blower, lights, accessories, etc.)

The wiring harness goes through a bunch of places I can’t access for maintenance and I can’t find evidence of a buss bar, in the places I can access, which I think would be the most likely culprit. If no one knows of a buss bar on a 270 that feeds the helm I think running a new wire to the main feed to the secondary breaker bank from the primary breaker box is likely my only solution.

 

[Lazy Daze]

Look at the back of one of the breaker panels I talked about

 

[Hoplite808]

Spent the better part of today doing some engine bay yoga and ran a new power lead for the 12v+ to the secondary breaker panel at the helm. But it had no effect.

So I switched gears and got some more wire and ran a brand new ground lead to the helm and everything works now with only 0.1-0.2 volts drop even with everything turned on. Now the radio and chart plotter don’t turn off when I turn the lights on anymore.

I did find a severely corroded ground buss bar on the starboard transom. It had three 8-10 gauge white wires and four 14 gauge black wires on it. I’m going to have to get a new one and some new crimp connectors for it next time I’m at the parts store. Not sure that’s even the issue with the helm but it’s gotta be an issue somewhere.