power to back of car

[Grimsey]

when running a power lead to the back of the car for a fridge ect what size wire do you guys recomend and sould i put a fuse in the line.

yes always fuse it as close to the power source as possible, in this case the battery. If all you wanna run off it is a fridge and maybe an auxillary output for a light etc 4mm is heaps. It has a continuous current rating of about 15amps.

[crankycruiser]

I agree with Tuff,
I have a fuse block under the bonnet near the battery that feeds things like my fridge, d/lights ect...

4mm should be heaps..

[taziiy]

Same as the others i have done what your wanting and i have a fuse link at the battery and 4mm wire running down to a water tight cigarette plug in the tray

if you are running several things from one power lead....... it would probably be a good idea to put a fuse near the battery that will blow below the limit of the cable....... and separate fuses for each item. .Say..... 45amp for the main line, and whatever the specified fuse is for the appliances being powered

[Grimsey]

cool thanks guys i will do it tomorrow.

[Nig]

Depending on what sort of fridge you are going to use, you may want to consider 6mm wire. I have a Chescold 3-way, and running it off 4mm wire it never worked real well - turned out it was never getting more than 11.5 volts due to the voltage drop in the 5 and a bit metres of wire between the battery and the fridge. :(
So I ran 6mm wire, with a relay and fuse right up at the battery end (relay connected to a switch on the dash) and now get 13.5 volts at the fridge - and cold beer ;)

[kitch76]

I would use 6mm fused at the battery and have each out put with a relay and another fuse.

[jackroov6]

I agree with kitch.
AS a auto electrician run 6mm and a relay up the front if you want the power to turn off with the ingnition. ;D
Given the voltage drop over distance 4mm is to small and does not allow a 15% tolarance for short circuits. ;D

Cheers ;D

I agree with kitch.
AS a auto electrician run 6mm and a relay up the front if you want the power to turn off with the ingnition. ;D
Given the voltage drop over distance 4mm is to small and does not allow a 15% tolarance for short circuits. ;D

Cheers ;D


Why would he fit a relay and turn it off with ignition when he wants to run the fridge off it? wouldnt keep the beer to cold once the key is off?? just on the other points made you arent wanting to allow for short circuits by the size of your wire, thats why you fit a correct size fused based on the current load and conductor diametre(ie wire size). 6mm is definately overkill for just a fridge as i said earlier 4mm has a continuous rating of 15amps, and considering my 40ltr engel draws less then 3 amps that gives him plenty left to run other stuff if he wants. 4mm is fine and shouldnt suffer from voltage drop at all over 5 metres if joints are soldered or crimped properly, as a comparison manufacturers use alot smaller wires to run things such as fuel pumps which draw alot more juice then fridges.

[Nig]

Depends on the type of fridge - if you are running a compressor type then maybe voltage dosent matter.
If you are running a 3-way (dont know what the technology in them is called but you make something outside hot and by magic the inside gets cold - just like the old kero fridges) the voltage counts for heaps - ie it dosent work a damn off the 11.5 volts that trickles out the end of a long run of 4mm wire.
And of course when we camp for the night it gets hooked up to a gas bottle, reducing the chance of a flat battery next morning.
I have my relay hooked up to the accessory circuit (tapped of the back of the cigarette lighter, and so it still works with the engine off if you want it to.

[nqgu]

I have a Chescold 3 way and I use 6mm wire fused at the battery and running off a relay that is connected to the ignition coil (so ingntion off=fridge off) I don't trust myself to turn it off otherwise, and a 3 way will flatten the battery in no time at all.

It worked a treat all the way thru Oz deserts.

[kitch76]

I actually ment switching the relay through a constant power source. The realy should supply u with a nice constant supply of power.

[Redfox]

G'day all. Just thought I'd add my 2 cents worth. In my truck I used 6mm twin sheaved wire to supply power and earth to two different sockets in the back as well as the trailer plug, and also one on the back of the centre console. I fused the supply at the battery using a 50 amp fusible link to protect the cable and at each socket I fitted 10 amp inline fuse holders to protect the accessories (flouro lights, fridge etc) if they should short out. Whether you use 4mm or 6mm largely comes down personal choice, and cost, unless you are going to use high current accessories. ;)

I'd probably use 6mm for insurance, remember, the bigger the cross sectional area of the cable, the less voltage drop ;)

[BLU-125]

Just don't use circuit breakers. On the first install some years ago the auto elec. installed a circuit breaker on my rear power point for my 'fridge.

Whan a short occured, the bi-metallic breaker got so hot openning & closing, it decided to weld itself together.

6mm cable makes bigger fires, eventually!

Just don't use circuit breakers. On the first install some years ago the auto elec. installed a circuit breaker on my rear power point for my 'fridge.

Whan a short occured, the bi-metallic breaker got so hot openning & closing, it decided to weld itself together.

6mm cable makes bigger fires, eventually!


Were you switching the breaker back on right after it tripped, without fixing the problem......naughty naughty

[BLU-125]

Nah, bi-metallic ones reset themselves!

Nah, bi-metallic ones reset themselves!


Point taken blu125, it's just that a lot of people just reset a breaker right after it trips, not supposed to do that.
Thats probably the only problem with circuit breakers, they're to easy to reset so people don't look at the problem......not good :(

I actually ment switching the relay through a constant power source. The realy should supply u with a nice constant supply of power.


Fair enough but it still makes no sence as this way the relay is constantly energized which adds another amp or so of current draw to the battery, doesnt sound like much but is 24a/hr over a day

[Grimsey]

Thanks for the info guys i have an everkool fridge, i have power to the back of the car now and its with 4mm and a fuse right at the battary however when i plug it in the light on the fridge comes up stateing there is not enough power. so after reading this i was thinking it may be the fridge but i put it into dads car an it worked fine. so i think i will try and get a bigger fuse case as the wire going in and out is less than 4mm which maybe causing it. otherwise ill try 6mm.

[taziiy]

this is interesting as i have run my brothers weaco off a 4 mm wire direct to a plug with of cause the inline fuse went driving all day camp from 6pm till nine the next morning with out the car running and when it got darker i had a fluro light running off the one in the dash till about 10.30 woke up in the morning and the car kicked over first turn of the key

[simsy]

I just bought 10m of 6mm twin sheath wire,(for an extention from the 6mm at the rear of my car)
cost me $2p/m i thought that was cheap enough. I'm for the 6mm for less voltage drop. I installed it and checked my volts. 12.69 rear of car 12.68 end of 10m extention.

[Humpy]

If your buying new cable to do the job and theres doubt about which size you need, why bother thinking about it. The big one might cost an extra 50cents/m and take up bugger all more space.

Its not as if your running kilometres of the stuff

[GUHOON]

Just don't forget a good earth too,all the power supply in the world is no good without an earth. ;)

[Redfox]

I just bought 10m of 6mm twin sheath wire,(for an extention from the 6mm at the rear of my car)
cost me $2p/m i thought that was cheap enough. I'm for the 6mm for less voltage drop. I installed it and checked my volts. 12.69 rear of car 12.68 end of 10m extention.


Simsy did you check the voltage with your accessories connected and switched on? Voltage drop can only be checked when there is a load on the circuit and the volt meter connected parrallel to the load. That's not to say I think you have a problem. I have a similar setup where I plug an extension lead into the 12 pin trailer plug and run the power into the tent/s as required and it works very well. Redfox.

[GQANDGU]

I would use 6mm fused at the battery and have each out put with a relay and another fuse.

Totally agree kitch - minimum 6mm cable fused at or near battery, plus each undividual output separately fused. May be an overkill now but you never know what you might want to connect later. I ran two lines - one with direct current and one via a relay from ignition. Gives more flexibility.

[jackroov6]

Sorry guys just to clarify the point I was making ;D

The relay point was to be used with a second battery connected the the alternator warrning light.So when the car cranks over only one battery is used(thus reducing the chance of two batterys trying to balance,causing two flat batterys!)
As the engine starts the alternator light goes out and th4e3 second battery is then being charged.
Also as a plus for this system is if your alternator was to fail anf the battery light stays on,you will only flatten one battery,leaving the second one for back up. ;D

As with the 6mm cable,this is for voltage drob as well as short protection.
No body wants a nice burnt wire from the front of the car to the back. :(

Also a point to remember DONT run your wires zip tired to you brake lines or other looms if possible.
Because if It does fry-up you will have no brakes.

This would be very bad!!

I hope this helps guys. ;D

[simsy]

redfox
i didn't have a load and the ignition was off. I'll have to plug in the double adaptor and plug the fridge in one and test the other.

[plado1]

i totally agree with hj45 - the bigger the wire the less voltage drop so you draw much less power to maintain same beer temperature. = battery life

i've used two-pin connector instead of cig-lighter conx, more secure therefore again less voltage drop

also left the cable loose (but hidden) so i can move the fridge around and even take outside when camped

i kept the chopped cig-lighter cable and wired in a two-pin in case i need to ever use someone's cig-lighter - but that's academic

that's what i've done and it works for me!

[nqgu]

this is interesting as i have run my brothers weaco off a 4 mm wire direct to a plug with of cause the inline fuse went driving all day camp from 6pm till nine the next morning with out the car running and when it got darker i had a fluro light running off the one in the dash till about 10.30 woke up in the morning and the car kicked over first turn of the key


You wont do that with a threeway fridge!
I ran 4mm and had a bit of a fire in my previous 4b...pretty damn scary!

[Craig]

when running a power lead to the back of the car for a fridge ect what size wire do you guys recomend and sould i put a fuse in the line.


I do these for a living mate so use 3 or 4 mm twin core wire. Use a fuse near the battery with a minimum 15 amp fuse but if running a fridge you'll have to look higher
Remember to solder all conections. Corrigations are your wirings worst enemy you can cause anything from poer failure/ shorts to a vehicle fire from not doing this job right. Use convalute/spiral piping that helps with the insulation of your wiring