I've just bought a boat, but the electrical systems need a bit of an upgrade before going cruising for any length of time. At the moment, All the 12V runs from a single starter battery, and there are on-board plug sockets to hookup to a mains line.

I plan to upgrade it to a larger leisure battery pack. I plan to use 3 of these 110Ah leisure batteries, and use this 600W inverter. I then want to use a connector like this to connect from the inverter to the hookup socket, so that the onboard plug sockets will provide 240V when the inverter is on, and can be removed and plugged into shore power when needed. I only need 240V for say, a laptop, computer monitor and speakers.

I just have a few questions...

1) Is providing power to all the sockets going to be an issue, or should I simply mount the inverter inside the boat and plug directly into it?

2) What amp rating split charge relay would I need? I'm note sure on the engine or alternator size, but it's a diesel narrow-boat type one.

3) Will the plug connector I have mentioned be able to safely carry the current the inverter can kick out?

4) Is this a sensible approach?

Here is the current and proposed layout... (Green is current, orange is proposed)

proposed layout http://arcticanaudio.com/STORAGEAREA/boatelectrics.png


  • 3
    If you can get a monitor that doesn't need 240V you are almost at the point where you can avoid producing 240V because you can get lap-tops that can be powered from a 12V source via a (much simpler) DC convertor and ditto the speakers I'd say. Work out what you really need and decide if 240V is the way to go.
    – Andy aka
    Commented Jul 30, 2013 at 11:53
  • 1
    I'm certain you meant to draw the batteries in parallel and not in series, that way they add current and not voltage. With 3 110Ah 12v batteries in parallel you have enough to power a much beefier inverter (each battery alone has 1200Wh in it)
    – crasic
    Commented Jul 30, 2013 at 23:16
  • Do you have a cat named Endor? Commented Jul 31, 2013 at 0:09

1 Answer 1

  1. 600W isn't much power. At 240V it means 2.5A compared to 16A (3840W) through your shore supply. So it depends on what exactly you expect to have plugged in and turned on. You may need to make a list and add up the power needs.

  2. Don't know

  3. Yes, a 13A plug and a 15A connector can safely carry a 2.5A current.

  4. Probably. Not sure about charging your 110Ah batteries in series. You realize that creates a 36V battery bank. Your alternator won't like that. Your schematic has insufficient detail to tell how big the fire will be. I've no experience of this but I'd expect you'd need specific provision (i.e. widgets) that allow three 12V batteries to be charged or discharged in parallel.

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