Salon lights and receptacles won’t work on battery power

[Bustoutanother1k]

79 Carver Voyager 28, 2 battery system. Everything works fine on shore power but when I disconnect, the interior lights and receptacles don’t work with selector on either batteries. The boat engine and fly bridge controls/panels do get power and engine starts. The boat is in fact new to me, did I wire the batteries wrong or am I making some silly mistake here? Or is that normal, I doubt it? Kind of stumped because they do work on shore power. I’m normally quite a skilled mechanic but this is my first boat with a house cabin and the electronic for such are a little alien to me.

[km1125]

The receptacles won't work when you're not connected to shore power unless you have a generator or inverter, both which would have been rare on a 28 (or even most boats in 79). If the lights are 120VAC type lights, then they would not work either.

[buster53]

Your boat has 2 entirely separate electrical systems. Your 12 volt is just like a car, starts engines, runs lights, radio, etc. Then you have your 120 volt system just like a house, to turn on 120 volt lamps, oven, microwave, AC, water heater, etc.
To run any 120 volt item, you must be plugged into shore power, have a genset or inverter and as mentioned, your boat probably did not come with an inverter unless a previous owner installed one.

[Bustoutanother1k]

Ahh, makes sense. I was under the impression that they could run on the batteries, as i believe the fridge runs on battery power when off shore power (maybe I’m wrong but I think I remember it running while unplugged). I indeed checked today and no inverter, although I’m tempted to add one, if only for running a light in the salon.

[buster53]

Many marine refrigerators are built to run on either 12 or 120 volts. Most suggest when turning it on after being off for a while as most of us weekend boaters do, run it on 120 to get it cooled down before going to battery power as it will cool down faster running on 120.

If you need a little more light, look into some 12v LED fixtures. They put out a lot of light using a fraction of battery power and while you are at it, replace any current light bulbs with LED equivalents. There are LED equivalent for just about any incandescent or halogen bulb ever made. They also put out a fraction of the heat which is nice in the hot summertime.