What makes your 12v system work off of shore power. We have a 2007 270 sundancer

B Hansen

New Member
May 12, 2018
5
Boat Info
2007 270 sundancer
Engines
Mercruiser
We don’t have 12 v off of shore power and only way to use cabin lights, frig etc is off of battery.
 
All the 12v stuff runs off the batteries. When you are plugged to shore power a battery charger installed in the boat by the manufacturer, keeps the batteries charged.
 
So confused by the 120volt ac panel switches and 12 v dc panel. We just bought this boat and were told we could turn off the batteries connect to shore power and frig, lights. Outlets and other electronics would work. So that’s not true we must have batteries on? Thanks
 

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If you think about it it makes sense. Aside from your fridge which runs on both ac and dc, the heavier draw appliances runs off of 120. When at the dock on shore power we keep our dc panel on so that we can run all the dc powered items. The essentials are dc so that you can run your water pumps, head system,radio and lights when away from the dock.
 
So confused by the 120volt ac panel switches and 12 v dc panel. We just bought this boat and were told we could turn off the batteries connect to shore power and frig, lights. Outlets and other electronics would work. So that’s not true we must have batteries on? Thanks
I think you're thinking too much. I also encourage you to read your manual.

Look at the panel. Anything in the AC section will work off 120V Shore Power. Anything in the DC section will work off 12V power. So, yes, you can turn the battery switch to "off" and still power the fridge and outlets - along with anything else in the 120V section. BUT, you have to have the proper switches on. In your picture, the outlets, fridge, charger and A/C are on, regardless of battery switch. You MAY have a dual voltage light above the galley - I'm not sure on your boat - you'll have to verify.

For what it's worth, when you're hooked up to shore power, you'll have your charger on so it's totally fine to also have the battery switches on.

FYI... there is no "270 Sundancer" in 2007. At least not in the US. Do you mean "Amberjack"?
 
They may have been referring to the fact that the Fridge is probably AC/DC autosensing (assuming original and both AC and DC still work) and that there is a AC light in the cabin. Otherwise as stated previously anything shown under the 12V portion of the panel will not have power supplied when you turn off the batteries.

-Kevin
 
To clarify all these posts:

1. All 12v stuff runs off batteries
2. The cabin 12v switch panel is feed by wiring run from the battery switch. So, the big battery switch has to be on for those 12v panel switches to do anything.
3. Some things bypass the battery switch and are wired directly from the battery to the device (such as bilge pumps). Check your manual to see what thes are.
4. The battery charger runs off of shore power. Keep it on at all times when on shore power in order to keep the batteries charged so you don't run them down using your 12v systems.
 
Fridge is usually the in,y thing that can run off of both ac or dc.
When plugged in to shore power I turn the 12 volt fridge breaker off and the 120 volt fridge breaker on. When away from the dock I do the opposite.
 
Fridge is usually the in,y thing that can run off of both ac or dc.
When plugged in to shore power I turn the 12 volt fridge breaker off and the 120 volt fridge breaker on. When away from the dock I do the opposite.

I always leave my 12 volt fridge breaker on because we lose power on the docks occasionally and I want the fridge and freezer to stay on.
 
Under those circumstances that makes a lot of sense.
I usually turn my batteries off when we leave the boat so it wouldn’t make a difference for me.
 
The AC Converter breaker in you picture should be on when you are plugged into shore power. Depending on your battery charger (AC Converter) it might supply 12V DC to the boat in addition to charging the batteries. The ProMariner models do this and it is a very nice feature. That allows you to run your lights, radio at the dock. That way you are not draining your batteries while at the dock.
 

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