12 volt wiring to standard accessory points
Submitted: Thursday, Aug 02, 2001 at 00:00
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Ron Holland
Note forExploroz editor - I tried to put this through yesterday but I'm not sure if it went through as it
has not yet been posted - I may have hit the wrong lever on this buzzbox
I own a 2000 Jackaroo SE T/D which has an 12volt accessory point in the
back cargo bay area. I have been looking at purchasing a 240/12 volt or
LPG/12 VOLT fridge freezer. I 'm told that a Chescold 3 way fridge
freezer must be wired direct to the battery. What about Engel, Wemo or
Waeco? Can anyone inform me if any or all of these should be direct
wired to the battery. I already have CB/
uhf radio, electric brakes, 12
volt wiring to the van coming off the standard dual battery system.
I'm told that the accessory wiring in most 4wds will not take the load.
If I want to run a freezer as
well and the accessory point is located there for
exactly that reason it does not seem right that there is a need to
direct wire additional appliances. Surely when you spend $50 grand+ on a
vehicle that all makes are wired to accept the demands of a 12 volt
fridge/freezer? Do all the above brands need to be wired direct or can I use the
accessory point.
How do others wire
1.CB/UHF Radios . 2 Electric Brakes to van 3. 12v Power to van 4. Fridge freezer
Or is this all putting to great a demand on the system and I need a third battery source?
I'd appreciate any advice on how others solve this dilemma. Thanks
Ron Holland
Reply By: Dion - Friday, Aug 03, 2001 at 00:00
Friday, Aug 03, 2001 at 00:00
Ron, 120 watts of power theoretically from a 12 volt system should support 10amps (P=IV). However as the Diesel Jackaroo supports about 13.5 volts, then 120 watts brings your current draw back to about 8.5amps.
The other area of concern is that as the socket is isolated when the ignition is off, you could almost bet that the wiring to that socket is as light as what is required to meet the rating requirements. There is nothing wrong with 'over engineering' and re-installing larger wire. Also take into consideration that four to five metres of wires is not very long, if it is loaded near its maximum, it heats up and increases resistence, and therefore causes a voltage drop, which then means your 120 watt applience is drawing more current (because of the P=VI relationship). Go as big as reasonably sensible, ie 6mm.
Another hint, having fridge/freezer, UHF/CB running direct from your battery, you are less likely to experience interference on your radio as the battery acts like a big asorber.
I don't know a lot about electric brakes to towables, so i can't offer any advice there, however with power to your towables, use at least 50 amp rated cable, and even consider installing an isolation switch under the bonnet so that when not regurly using the power socket at the back for your caravan, it stops some twit inserting a piece of wire between the two poles and causing damage to the vehicle, battery and wiring.
Cheers,
Dion.
AnswerID:
834
Reply By: Tony- Friday, Aug 03, 2001 at 00:00
Friday, Aug 03, 2001 at 00:00
Ron, The laod on your second battery is not the problem. Your van brakes will only be working when the moving and thus motor/alternator running (I hope!). My experience with a large (60l) fridge in a LC 80 was to by a cheap 240v household extension cord and run that from the second battery through a second fuse box and buzz bar to the back for the fridge. Worked fine when the motor was running but when it wasn't, the fridge would not cut in. It gave a 'low power' indication as if the battery was flat (i.e. below 10.5v). The battery was not flat - the problem was traced to the wiring. It was suffering too much voltage drop for the fridge to start. I replaced this wiring with 8mm cable and have not had any problem since. P.S. I left the extention cable in place and use this for 12v lights that draw less than 1 amp. Here is a trick - the extension cable is 3 core, active, neutral and earth. If you connect the active and neutral to positive 12v and the earth to negative (of course), and leave the 3 pin female socket on the end of the cable, you now have 2 x 12v supplies at the rear for lights or air bed pump etc. Buy a second extenson cord and replace the female 3 pin socket with twin cigarette type female sockets (2 positive wires, 1 common negative). Now lets say when you
camp in a Nation Park that has a car park that you can't get your car near the tent, plug in an extention cord to the car socket, plug in the modified extention cord (with the cig sockets) to that cord and then plug in your lights! Ive often run 30 metres or more from the car to the tent for lights. Voltage drop with low amperage draw is negligible.
AnswerID:
837
Reply By: Paul - Wednesday, Aug 08, 2001 at 00:00
Wednesday, Aug 08, 2001 at 00:00
Firstly, I agree totally with Graham's comments abou the SUICIDE PLUG, don't even think about it.
I don't want to repeat everyone else's valid comments so my different tack is this - Chescolds require far more current than Engels and etc due to their nature of their operation, so firstly
check the amp rating in the manual and
check that with the amp rating stamped in metal on the Chescold. The recommendation to use a direct wire is a matter of safety, thin low amp rated wire attached to a higher current drawing unit means, as has been alluded to, one burnt out Jackeroo on the side of the road and possible a denial of an insurance claim.
Good luck. Don't stuff around with this stuff if you are not sure what you are doing - and don't just buy 6mm wire, work out what you safely need according to the maximum current draw of your fridge, and definitely - as Graham said, use an in-line fuse - cost about $1.20, cheap insurance against losing everything.
AnswerID:
860