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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> 12V installation into a mains wired mobile home https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1340694589 Message started by Peach on Jun 26^th, 2012, 8:09am

Title: 12V installation into a mains wired mobile home
Post by Peach on Jun 26^th, 2012, 8:09am

Hi all, I'm in the process of buying my first mobile home which will be sited in the wilds of Donegal and as such will have no access to mains electricity or water. It's wired to be connected into the mains but my hope is to run a solar panel with a deep cycle leisure battery producing enough juice to run 12V lights, a water pump and part of the fridge (the fridge is gas power but needs a few amps to ignite). The light bulbs are standard bayonet which fit the into the mains wired sytem but run off 12V. There is a small consumer box which is where I hope to introduce the battery (no idea how though). Has anyone any advice, tips or know of any info on the web that can guide me?
Thanks in advance, Brian

Title: Re: 12V installation into a mains wired mobile home
Post by big_all on Jun 26^th, 2012, 1:14pm

how do you plan on charging the battery ??
you can charge your mobile directly from the battery

Title: Re: 12V installation into a mains wired mobile home
Post by Peach on Jun 26^th, 2012, 1:48pm

Thanks for the reply: My aim is to keep it as simple as possible so the solar panel connects directly to the battery via a solar panel controller and then i patch it into the mains wiring (not connected to mains obviously) but it's at this point I'm unsure. How exactly do i connect it to the mains wiring. It's only really the lighting loop I'd be looking to have current running through but I am unsure how to phsically connect it. As i've mentioned there is a small fuse box but quite how to marry the 2 elements together is another matter.

Title: Re: 12V installation into a mains wired mobile home
Post by Flashbang on Jun 26^th, 2012, 4:21pm

Hi
While I'm no mobile home sparkie, wouldn't using a static inverter be simpler?
Run the inverter from the battery and then use its 230volt output to feed the caravan. Then if the van was ever moved to a location where mains power is obtainable or you invest in a small generator, leaving all mains items and feeds are still in place!

Title: Re: 12V installation into a mains wired mobile home
Post by CWatters on Jun 27^th, 2012, 8:50am

I'd suggest posting the question on the caravan forums. Bound to be people who have done this.

I'd be looking to..

Fit battery near existing 230V distribution board in the van
Fit some sort of 12V distribution/fuse board and battery isolation switch.
Disconnect lighting circuit from 230V board and extend/reconnect to the 12V board.
Run a new 12V feed to the fridge.
Fit a battery charger (with a float setting) between the 230V board and the battery so battery is allways kept in top condition when 230V available.

I suppose you could also fit an inverter between the 12V board and the 230V board but you wouldn't want the inverter powered all the time.

Various isolation switches also needed, for example to prevent the following loop... battery -> inverter -> 230V -> charger -> battery

Perhaps also think about the wire guage required..

50W at 230W = 0.2A
50W at 12V = 4A

Same load but more than 20 times greater current. Obviously you wouldn't fit 50W 12V halogen down lights but just keep it in mind. I read somewhere that some people use 12v 600W hair dryers that draw 50A.

Title: Re: 12V installation into a mains wired mobile home
Post by Peach on Jun 27^th, 2012, 3:48pm

thanks - I think the inverter would need a bank of batteries to make it useful and a correspondingly big array of solar panels so I'll rule that out. I'll be using low voltage 12v led bulbs so the exisiting cabling will be fine and it's generally windy enough to negate the need for hair driers! I'll try some caravan forums as advised but thanks for the pointers CWatters.

Title: Re: 12V installation into a mains wired mobile home
Post by TIMBA-WOLF on Jun 27^th, 2012, 4:22pm

just to let you know that i have small (1/2 a shoe box size) inverter fitted to the rear compartment of my suv, so when on site i can charge batteries for power tools, even run a small desktop printer and laptop off it (its a small 250watts max) and barely touches the suv's battery life, even without the engine running... inverters are no longer large items, well don't need to be...

Title: Re: 12V installation into a mains wired mobile home
Post by CWatters on Jun 27^th, 2012, 7:37pm

I've also used a small inverter to run a laptop, printer and some sports timing equipment. Some inverters are >85% efficient so you don't loose much compared to running direct off 12V.