Plugging invertor into shore line

[Louisesjpp]

My van has an invertor (seemingly rated at a massive 7kW) which is connected to one socket only. The other sockets scattered through the van are connected to the shore line (ie, site hook up power) and the two don't mix for "safety reasons". I'm guessing this is to do with phase alignment: if the invertor's running and mains voltage is applied, and their phases are one-eighty out, the invertor will see a dead short and go pop.

The trouble is we don't use hook-up, the solar, house battery and inverter so far seems to be all we need, and we've ended up festooned with extension cables in the van running from the single socket.

I hit on the idea of plugging the hook-up cable into the invertor's outlet socket and plugging the other end into the van's external hook-up point, so the invertor feeds to van's mains circuit. This way, we'd have power on all the sockets and there'd be no way we could forget to disconnect it if ever we decided to hook up. My husband was nervous of this solution, and asked for further research.

So, will it work?

 

[Cush]

Can you turn your ehu charger off otherwise it might get messy. Not sure how efficient it would be.

 

[PP Bear]

I’m sure someone more knowledgeable than me will be along to assist with an answer, but Saturday nights can be a little slower to get an answer to you.

It’s definitely not anything to do with a Saturday night, bank holiday weekend and wine

 

[olley]

Its what I do the ehu lead is plugged into the inverter but you do need to be able to turn your battery charger off.

 

[olley]

Can I just say a 7kw inverter is massive unless you have a very large stack of batteries (1000AH) I would be very careful how much load I put on the inverter as it could kill your batteries.

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[pappajohn]

You would also need to turn the fridge 230v off and run on gas only.
You don't say what size battery/ies you have but it seems a single battery.
That isn't going to last very long

 

[MisterB]

i dont know whether you are looking to 'upgrade/change/downgrade' your system, but i recently fitted a Renogy 3000W inverter - check them out on youtube (though most of them are 2000w models)

on my setup (and others have better/different ones) i have two outputs from the inverter - they feed two separate circuits with two outlets on each 'circuit'.

one 'circuit' feeds the microwave and (will do soon) an external socket
one 'circuit' feeds the lounge and kitchen area

But back to the Renogy inverter - it also has a 240v input via EHU (and through the on board consumer unit) aswell as the 240v outputs. The best part about this is that if connected to the EHU then ALL sockets work, (due to a 'pass through facility) if no EHU and inverter is turned on, then the two inverter fed circuits work!


another bonus is that if EHU drops for some reason and inverter is on, then everything keeps running with no power interruption, if EHU comes back on then it just 'switches' back to EHU supply!


it doesnt answer your question re plugging the inverter into the EHU supply, but it offers another option just to power some circuits you want to be 'live' at all times.

 

[Tombola]

Sure you can, but as others have said, fridge and battery charger to OFF.

then dont forget to unplug when whizzing down the motorway

 

[Lenny HB]

Can I just say a 7kw inverter is massive unless you have a very large stack of batteries (1000AH) I would be very careful how much load I put on the inverter as it could kill your batteries.

More like 3000 ah of batteries unless Lithium.

 

[ChrisL]

Perhaps the victron multiplus inverter charger would be a better solution for you, check them out on YouTube.

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[autorouter]

What you describe is perfectly possible, it's done on many motorhomes, there are various methods to implement it, depending on how much you want to integrate it into your system. You might need to rejig a few connections.

There's two problems with just wiring up the inverter into the motorhome mains system. The first is the obvious one that you have mentioned, that hookup power and inverter power don't mix unless they're carefully designed to. You can fit a manual switch that switches the sockets between hookup and inverter. Or you can fit a relay (a transfer relay) that will automatically connect the inverter when there's no hookup, and switch over to hookup automatically whenever it's plugged in. Some inverters have such a relay built-in for this purpose.

The other problem is, when you're off hookup running from the inverter, you don't want the mains charger to be running from the inverter, charging the batteries, which are powering the inverter... Also there might be other things you'd rather not be running from the batteries/inverter, like the water heater, room heater and fridge 240V element. So usually the mains is split into the inverter loads and non-inverter loads, with the non-inverter loads only powered from the hookup.

One more thing, a 7kW inverter sounds very large, more like something you would find in a house installation. Can you post a picture of the label? It might be a 3.5kW (7kW peak power) which is more like what I would expect in a motorhome. I have a 3kW inverter/charger in mine. Also how big is your battery bank, and is it 12V, 24V or 48V?