Mainship 430 lighting question

The main cabin in our (new to us) 2003 430 trawler has several light switches that were labeled by the PO 12 volt and 110 volt. The lights labeled 12 volt turn off when I turn off the main breaker in the distribution panel. The lights labeled 110 volt turn off when I turn off the shore power switch. However all the light fixtures are the same and are marked G4 24V 20W Max. I have the factory wiring diagrams and they don't help. What am I missing?

So the 12 volt lights are wired straight to the main fuse bus and the 110volt lights are wired straight to shore power? Did I get that right?

The 12 volt lights are on their own breaker in the panel. There is also a main cabin 12 volt breaker and that is the one I turned off. The 110 volt lights are also on their own breaker in the AC section of the panel. I turned off the shore power to make sure all AC power was off. Also, the inverter was turned off. I didn't explain very well. It looks like all the light fixtures have the same G4 12 volt bulbs in them. What I don't understand is, if they are 12 volt bulbs, why do they turn off when I turn off the shore power?

Might be some kind of in-line converter in your 110v lighting system that's supplying those fixtures with 12v?


Most stuff like computers and TVs and what not are actually running on 12v these days, even when your supplying them 110v. Our AC/DC fridges are the same; always running on DC, no matter what the initial power source...


Just a thought...


-Chris

my thought would be to test voltage at the bulbs to confirm that there is a voltage transformer somewhere

I'll check the voltage the next time I'm at the boat. My guess is there is a transformer that isn't shown in the wiring diagram. I think I'll take a look behind the electrical panel.

I have the same boat. Most of our interior lights only operated on shore power (even though they were 12 v) because they were wired thru step down transformers (120 v ac to 12 v dc). We removed 4 of the 6 transformers on our boat and wired the lights directly to the 12 v panel. Three of the transformers were located behind the electrical panel and one more behind a trim panel in the salon. The transformers are about the size/shape of a soda can.

The design of this by Mainship seemed unnecessarily complicated and not workable for anchoring on battery power. BTW we changed all the bulbs to LED's.

120 volt ac to 12 volt dc......very common. Remove transformer and run on 12 volt is what I would do after converting the bulbs to LED.

Thanks Temptation, I'll look for the transformers. You're right, the boat doesn't seem set up for extended anchoring. The 12 volt loads are split between the two 8D start batteries instead of house batteries. Not shown in the wiring diagrams are three 8D batteries that power the bow thruster and also the Xantrex inverter/charger, whose sole purpose seems to be powering the lights and the 110 volt refrigerator. Is your boat set up the same way?

porman said:

You're right, the boat doesn't seem set up for extended anchoring. The 12 volt loads are split between the two 8D start batteries instead of house batteries.

Click to expand...

That's a common Luhrs Group setup. Often each "start" battery also powers approx. half the house, and approx. half the bridge. In our case, one powers bridge electrics (lights, gauges, etc.) and the other powers electronics (plotters, radar, etc.).

FWIW, we've learned to live with it, partly by increasing amp hours on each bank, partly by simply charging batteries twice a day at anchor (gotta cook anyway), and partly because our separate genset battery provides a safety net.

-Chris

On our 430 we have an issue with our lower helm ceiling light (x2) staying on regardless of the switch position - located to the right of the wheel. Light randomly turns on and off on its own. When the light is on the switch does not turn light on or off. When the light chooses to be off the switch works. Switch has been replaced and we have installed LEDs.
Also doesn't appear to be a problem in the summer but starts up in the fall. We heard there is an electrical/conversion unit that all lighting is connected to - 110/12v - could this be the issue. Where is it located?

Sorry for the slow reply, I just saw your battery question. Our setup is different from yours because we don't have a thruster nor an inverter. We had an electrician permanently combine the two battery banks that split the house loads.

See my post of Jan 2015 earlier in this thread

we have a 2003 390. Each space (staterooms, saloon, head) has at least two switches. Each switch operates half the lights in the space (except the saloon which has 5 switches). One switch is 110V and one is 12V. None were marked so it took a little playing around to figure out which was which.
John