12 volt novice

[Rainman Advanced Member Find all posts View Profile Close Rainman]

Things are a little quiet in the 90 series list so I thought I'd post here instead of making a fool of myself elsewhere.

I'm a complete novice when it comes to 12 volt and despite reading lots, I remain one still, so be kind and assume I know nothing.

I have just installed a dual battery system in my recently purchased 2002 TD RV, so now seems like a good time to install some power down the back to run the usual electrics.

The duel battery system I installed came with easy to follow instructions and was a piece of cake to fit, but the power supply to the rear has me baffled a bit as I've always had it done by auto sparkys before.

I run a 39 litre Engel fridge and an ARB light normally, swapping the light with a 150w inverter when on the road. Last October we bought a camper trailer, it also has a fluro light inside and an outlet on the tailgate kitchen for the ARB light. I am also hoping to install a decent air compressor in the back of the vehicle in the near future (Bluetongue IV or Bushranger Max Air).

I'd like to install three power points, one on the drivers side for the fridge and two on the other side for the light and inverter etc. I am planning on using the Hella style plug.

What size wire will I need to run these items, and perhaps more importantly how does a layman like me calculate what size is needed? I presume I can run the inverter and light (and eventually compressor) off one cable as long as it is heavy enough?

I know I'll need to include fuses, but whats the best location? I have heard of installing an ancillary fuse box inside the vehicle or on the firewall, whats involved with that, or are inline fuses best for this type of job? Is it best closest to the battery or to the plug? What do I need to earth?

I also need to run power to the trailer to run the camping lights, again whats the best arrangement? Has anyone found an easy route for the wiring from the back of the vehicle to the rear bumper of the vehicle for a two pin plug?

Your probably thinking it sounds like I should just take the vehicle to an auto electrician and get them to do it for me, but my lack of knowledge in this area really frustrates me, so what better way to learn than do it yourself?

Remember to keep it simple for me. ops:

[Guest Close Guest]

Hi
I am not a professional in electrics but I had a friend help with a few things that I can pass on,
1. we made a wiring loom from the aux battery to a new fuse block which was mounted near the original one under the dash and run it under the door trims to the rear having 3 outlets. make sure that the plugs for each item cannot come off through vibration. all aux power runs through the fuse block. all outlets should have a dedicated fuse, all connectors were soldered
2. to have power to the trailer we run 2 big wires( about 10mm outside diameter) from the second battery through a 100amp fuse to the rear of the car and attached it to a 150amp anderson plug, (the fuse is protect the battery in case there is a short along the car somewhere). I have a 3rd battery in the trailer which can be charged through the anderson plug, if you disconnect the car from the ct the lights will still work, there is another fuse block in the battery box on the trailer to seperate every item. the big thing with the fuse block is to isolate any problems so you don't loose everything if one thing has a problem

[Roktruk Junior Member Find all posts View Profile Close Roktruk]

Engel fridge wiring

It's worth spending the $$$ on the genuine Engel cable, it has an in line fuse and a screw in plug at the fridge end. It's 2 core, run it directly to the auxillary battery positive and negative. I've had mine 15+ years and the fridge has always worked.

[Laurie Lurker Find all posts View Profile Close Laurie]

12 volt

Hi Rainman

Found this thread under the "search" so am trying to avoid looking like a goose and seek your advice.
Next week we are heading north and will be away from power for a couple of weeks. Have purchased a DSE 300 watt Inverter but I am a bit frightened to plug it in as it says that the vehicle batteries need to be positively earthed or it can ruin your electrics etc

Do you have any warnings or should it be ok.

Also can you charge things while travelling or should the engine be off?

I am hoping to charge things like iPod speakers and phones but would be grateful for info regarding lights etc

I will have the Engel running off the Dual Battery post but also wonder if there is an overload possible by running the inverter of the cig socket at the same time

Dumb questions probably but if I blow the electrics I will feel dumber

Regards and best wishes

Laurie

[Rainman Advanced Member Find all posts View Profile Close Rainman]

Just remember Laurie, I was the 12 volt novice back then and remain one to this day, so others may not think much of my advice. It seems with 12 volt there is always more than one way to skin a cat.

I use a DSE inverter as well, but its only 150 watts. I ended up with three power points in the rear, one specifically for the Engel and two sharing the same cables that I use for the inverter and light.

I run my inverter all the time charging batteries mostly, but I seem to remember the instructions saying you should turn it off while starting the engine. No problems so far.

If you run your inverter off the cig socket it will be running directly off your starter battery (unless you have modified it otherwise) so you'll need to have the key in the accessories position (I think?) in order to get power to the socket.

Most seem to agree that using a cig socket for anything other than the lighter will eventually lead to failure/disappointment/frustration. I changed the plug in my inverter so I could plug it into the powerpoints I installed in the rear.

Does that help?

[Laurie Lurker Find all posts View Profile Close Laurie]

12 volt

Thanks Rainman

I will need to add power points after we return
Meanwhile I will plug the inverter into the fridge outlet and charge the phones and ipod speakers while we are travelling keeping an eye on the fridge temp

I will plug the inverter in tonight for a test now that I am confident that its not going to blow the Prado electrics

This is our first time away from power and drinking water - its very exciting but so much to cover

Thanks again for your help

Regards and best wishes

Laurie

[Big Fella Senior Member Find all posts View Profile Close Big Fella]

Just remember that if wish to charge any sensitive electrical items like laptops and other electronics, please make sure that you have a pure sine wave inverter and not a modified sine wave inverter as the potential for damage to the equipment is high.

Just my 2cents worth.

[Laurie Lurker Find all posts View Profile Close Laurie]

12 volt

But worth $$$$$s

Thanks Big Fella

My main concern was damaging the prado electrics

The Inverter is pure

Many thanks

[2002TX Junior Member Find all posts View Profile Close 2002TX]

I too am a 12v (any volt for that matter) novice, but have recently spent lots of time trying to learn more, as I am in the process of trying to achieve the same sort of thing as you. Key things I have picked up, and just info I have sourced elsewhere:

1. Wiring from the battery to the back of the vehicle should be at least '6 B&S', which is around 14mm2. You should run both a positive (red) and negative (black) cable to the rear, ideally the twin sheath cable that has both as well as smaller signal and power cable for trailer brakes. Earthing at the chassis at the rear is less than ideal as steel is high in resistance.

2. Don't forget a suitable fuse or circuit breaker on the positive cable at the battery end so a short circuit doesnt end badly.

3. Outlets/sockets need to be suitable for the amperage they will be subjected to. I believe the standard lighter socket is only rated to about 10 amps. Calculating amperage is easy: wattage divided by voltage equals amperage. So in the scenario you mentioned, 150w divided by 12v equals 12.5amps. Lots of people seem to recommend 'Anderson' plugs for higher amperage.

I ran power from the standard battery setup to the rear of my 95 and fitted an anderson plug, after directing the smaller power cable to give constant power to the factory lighter socket. Ran the cable along the passenger side under the carpet in the existing cable channeling. There is a grommet you could run power cable through to get to the underside of the car, it is under the passenger side tail lights (I used it for my extended breathers).

So now I can plug in my air compressor via an Anderson plug in the rear, vs using alligator clips on a hot dirty engine at the end of a hot day at the beach. I ran enough cable under the bonnet so that when I get a dual battery system it can be connected easily.

Hope the above helps!