12v 240v

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Bestman

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I'm a little confused about the electrical setup on a prospective boat. She has 2 x 95Ah batteries for domestic use, and five 240v plugs. Am I right in thinking that in the absence of an inverter the plugs will only work when plugged into shore power? What if you wanted to run stuff like a TV or Microwave when shore power is unavailable? Do you buy 12v kit or is an inverter the solution. What about little things like charging a laptop? Would an inverter linked to a single plug independent of the shore power plugs be a solution?
 
You've pretty much answered your own questions, there. Mains sockets are for when you're on shore power. If you want TV or a microwave, you either have to get 12V stuff or run an inverter or a genny. A decent inverter will have a 'pass through' facility, so it is connected to the main boat ring main, and passes shore power through when it is available. For laptops, phones etc, you may be better off with one of the small 150W can type inverters from Halfords, Maplin or most anywhere and plug it into a 12V socket rather than hard wiring it in..
 
On boats with 12v DC & 240AC these are 2 seperate systems.
240V AC will opertate the 13A sockets, Immersion heater and battery chargers etc when connected to shore power .

The 12V DC ( some boats operate on 24V DC)
Normaly have 2 sets of battery banks 1 for starting one engine only, and the other for the 2nd engine and on board 12v DC lighing, power and dual supply fridges .

Inverters 12DC - 240AC come in various sizes and require high DC currents to support low power AC cequipment ( Microwaves etc, OK for Lap tops

There are AC Alternators on the markets which will mean running 1 engine to provide 240V AC to the mains equipment
If you go this route ensure you install it on the colorefier circuit engine. so you get hot water at the same time.

If you require AC power when away from shore powrer, on board generators with auto change over switches are the best options.
 
Some shore power supplies are limited in the amount of electrikery you can use at any one time.

Some are limited to 10amps ( and if you are using a 1kWatt fan heater and you either turn on the kettle or microwave oven - POP off goes the supply voltage until you have re-set the trip.

Might be worth thinking about 24volt microwave (from a truck shop), not sure about any good 12volt microwave ovens. also consider LED lighting much has been written on this subject over the years.

The above might prove less problematic than using inverters and making sure they are disconnected when shore power is applied?
 
12V and 24V microwaves will be no different, apart from the fact thata 12V one draws twice the current. Either way, an 800W microwave will draw 80 Amps or so, and more on start up.

Depending on your AC requirements, an inverter will auto switch off: our 2kW job has an input socket from the shorepower connector and the output then feeds the boat supply (except the battery charger, which is direct to shorepower). If the inverter is running and you connect shorepower, it automatically drops out of the circuit and cuts back in when shorepower goes. The changeover is not instantaneous - it takes the inverter a second or two to wake up, but other than that it's seamless. It does draw 200 Amps flat out so we have a big battery bank, and it's located two feet from the batteries to minimise the cable run.
 
Many thanks for all the advice.

I think I'll stick to 12v stuff and consider a 240v alternator in the future if we can't manage; I understand the engine would have to be running though.
 
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