# Thoughts on electrics



## tugboat (Sep 14, 2013)

When I start my engine the hab 12volt electrics turn off automatically, presumably via a relay under the bonnet somewhere. I assume that is an industry standard practice?

My fridge only has access to 12volts when the engine is running (I understand the logic of that when van has basic battery provision).

I now have 200W of solar panel with MPPT controller fitted. I have 2x110Ah batteries.

I feel it would be useful to have hab 12volt electrics available while driving, to enable charging of devices while the alternator is in action.

There have been a couple of mentions recently, including Andy's Techno thread, about fridges running on solar while parked up. I cannot do that, as my fridge 12volt goes off with the engine. Clearly, running on gas while on a ferry or in enclosed space is a big no-no.

What is the best way for me to modify my electrical system to give me more flexibility of usage, while ensuring I don't compromise safety or the integrity of my whole electrical system?

Any thoughts please?


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## GEMMY (Jun 19, 2006)

Surely your cigar socket is live whilst driving, plug accessories into that.

tony


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## listerdiesel (Aug 3, 2012)

Fridges take about 100W or 8amps or so, many cigar lighter sockets are not rated for that current continuously so you may find wiring overheating or similar problems.

The 12V car feed is deliberately switched off with the engine as it was never intended to be used without the alternator supply being available, 8Amps out of 100 or so from the alternator is no problem.

If you want to run the fridge off habitation batteries, I would look and see if your solar controller LOAD terminals are in use. These would allow the fridge to run off the habitation batteries and would have low voltage protection cut-off.

Then you'd have to have a relay switching from hab batteries to car battery when the engine was running, that gives you the best of both worlds.

A simple 12V 30A car relay, running off the alternator warning light connection should do the job.

Peter


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## GEMMY (Jun 19, 2006)

In case there was a mis-understanding, I was advocating the use of the cigar socket for various usage/charging of accessories, NOT the fridge/freezer :wink: 

tony


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## listerdiesel (Aug 3, 2012)

GEMMY said:


> In case there was a mis-understanding, I was advocating the use of the cigar socket for various usage/charging of accessories, NOT the fridge/freezer :wink:
> 
> tony


Fully understood, Tony, I was just pointing out the limitations of use at high currents for long periods.

If anyone wants to run at 10+ amps, this socket is the thing to use, with a fused feed from wherever:

http://www.ebay.co.uk/itm/140474575058

with this plug:

http://www.ebay.co.uk/itm/400667401303

Peter


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## tugboat (Sep 14, 2013)

GEMMY said:


> Surely your cigar socket is live whilst driving, plug accessories into that.
> 
> tony


I use those for the small stuff (phone/satnav etc) but I have a 12volt socket in the tambour cupboard in the rear and was thinking it an ideal way to charge the laptop whilst keeping it in a safe secure location.


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## tugboat (Sep 14, 2013)

Thanks, Peter, I understand what you are saying.

The relay control circuit though.........can you just explain that again please? Are you meaning to take the live to the relay from a connection on the alternator itself? I'm confused by the reference to the warning light.

Thanks.


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## Abacist (Jan 27, 2014)

*Thoughts on 12 volt electrics*

I have a 2010 Fiat 160 maxi cab and have the benefit of 2 12 volt sockets in my dashboard as original fitments by Fiat. One, the cigar lighter socket, is rated at 20amps with a 20 amp fuse and the one beside it is clearly labelled 180 watts max presumably for low current charging/running like Sat Navs and Mobiles etc, protected by a 10 amp fuse.

The 12 volt socket in the bedroom is also limited by a 10 amp fuse so for low wattage items only protected by a 10 amp fuse on the Sargent unit in the hab area.

Just tested all this out as I've bought a German 12 volt air compressor to pump up my tyres and air suspension so it needs a 15 amp feed which the cigar lighter socket can cope with.


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## Abacist (Jan 27, 2014)

*Thoughts on 12 volt electrics*

I have a 2010 Fiat 160 maxi cab and have the benefit of 2 12 volt sockets in my dashboard as original fitments by Fiat. One, the cigar lighter socket, is rated at 20amps with a 20 amp fuse and the one beside it is clearly labelled 180 watts max presumably for low current charging/running like Sat Navs and Mobiles etc, protected by a 10 amp fuse.

The 12 volt socket in the bedroom is also limited by a 10 amp fuse so for low wattage items only protected by a 10 amp fuse on the Sargent unit in the hab area.

Just tested all this out as I've bought a German 12 volt air compressor to pump up my tyres and air suspension so it needs a 15 amp feed which the cigar lighter socket can cope with.


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## VanFlair (Nov 21, 2009)

Hi tugboat

Our fridge runs off habitation 12v when the solar regulator works out that there is spare solar power to do this with (Votronic regulator with AES terminal), you need an AES fridge with a S+ terminal or put a diode onto the alternator wire to the fridge D+ to prevent connection to -ve. 

If you connect to the load terminals on the regulator I would be careful that the low volt protection is not too low as the last thing you want is the battery going down just as the sun goes in and you have to wait till morning to charge.

Andy Techno does it differently again but he is clever with elektrikery stuff.


Our habitation 12 volts stays live while we drive but not 100% sure, if I want to charge anything I put the inverter on and charge from the 240v sockets.

Martin


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## readyforoff (Dec 28, 2013)

tugboat said:


> Thanks, Peter, I understand what you are saying.
> 
> The relay control circuit though.........can you just explain that again please? Are you meaning to take the live to the relay from a connection on the alternator itself? I'm confused by the reference to the warning light.
> 
> Thanks.


Try not to meddle with the alternator wiring Tug. Much easier to use a TEC3M. It'll kick in when it sees rising voltage. I have one on the towbar to charge my Toad.....


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## readyforoff (Dec 28, 2013)

*Re: Thoughts on 12 volt electrics*



Abacist said:


> I have a 2010 Fiat 160 maxi cab and have the benefit of 2 12 volt sockets in my dashboard as original fitments by Fiat. One, the cigar lighter socket, is rated at 20amps with a 20 amp fuse and the one beside it is clearly labelled 180 watts max presumably for low current charging/running like Sat Navs and Mobiles etc, protected by a 10 amp fuse.
> 
> The 12 volt socket in the bedroom is also limited by a 10 amp fuse so for low wattage items only protected by a 10 amp fuse on the Sargent unit in the hab area.
> 
> Just tested all this out as I've bought a German 12 volt air compressor to pump up my tyres and air suspension so it needs a 15 amp feed which the cigar lighter socket can cope with.


Hi, I know compressors can come with cig lighter type power cables but it will melt a cig lighter because the connection isn't sound enough. Run a 4mm2 supply to wherever to operate it. I nailed my comp down in the garage and cabled it to the leisure. Air line reaches all 5 tyres.....


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## 747 (Oct 2, 2009)

Hi Tugs.

European vans have the 12 volt still live in the Hab area. It is only British made vans that disconnect the 12 volt on engine start. It should be easy enough for an Auto electrician to alter yours to the European spec.

Another way to do it is to have a dedicated multi-plug direct from the Hab batteries with an appropriate fuse installed.

Either way is an easy fix.


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## Brian-the-Snail (Dec 1, 2011)

Hi Tugboat,

I wired in 2 x 12volt cigar sockets to the load terminals on my mppt controller and I charge netbook, phone, kindle and tablet from these.
I have not been interested in running the fridge from solar but Andy ( Techno100 ) seems to be the man to ask about that.
As Peter ( Listerdeisel ) says you need to make sure that the sockets and wiring can take the load before hanging some heavy weight kit to them, that is the advantage of wiring to the load terminals, you can fit what is required.

Clive


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## tugboat (Sep 14, 2013)

Thanks, everyone, you've given me ideas to investigate.


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