12 volt wiring to standard accessory points

Submitted: Thursday, Aug 02, 2001 at 00:00
ThreadID: 338 Views:13071 Replies:10 FollowUps:2
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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
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Reply By: Rod - Thursday, Aug 02, 2001 at 00:00

Thursday, Aug 02, 2001 at 00:00
Try it, plug in your fridge, if you blow fuses then you know its not safe to use.
AnswerID: 825

Reply By: John Wood - Friday, Aug 03, 2001 at 00:00

Friday, Aug 03, 2001 at 00:00
Rod, I feel that your answer to Ron's question about wiring could be misleading. What if a larger fuse than standard has been fitted at some stage. The possibility then is overheated wiring with subsequent failure of a not too tight connection or wiring installation. Zappo. One fried Jackaroo.

Ron, I believe that it is best to run your acessories off of your 2nd battery with a seperate fuse box. When they say to run the fridge directly off the battery they mean not to take it through the normal wiring loom. I do not know what size wire they run to the rear plug but, being cynical, I would not expect it to be over large. Run a nice heavy cable, at least 6mm, to the rear and get a better plug/socket combination to replace the cigarette lighter type that is usually factory fitted. While you are at it fit an additional weatherproof socket somewhere at the rear to use for an outside light or other purposes. If you are not too ofay with the electrical side get your auto elec involved. P.S. The better plug/sockets are readily available at caravan supply places.

Cheers, John
AnswerID: 832

Reply By: Dion - Friday, Aug 03, 2001 at 00:00

Friday, Aug 03, 2001 at 00:00
Ron, ask Holden, they should be able to answer what the maximum continuos current allowable is. Is there any mention of this in the Jackaroo 'glovebox book'? Holden Service guys should be able to answer this, if not immediately, they should be able to find out. Is the socket live all the time, or only when the ignition is on?
In Mums Jackaroo (98/99) and my Rodeo (both diesels) I have wired the radio's direct to the battery, with light wire, CB radio's draw less than an amp each. I have wired in fridge sockets on both vehicles using 6mm wires (pos and neg) direct to the battery, and have no problems with either installation.
Cheers,
Dion.
AnswerID: 833

Follow Up By: Ron Holland - Friday, Aug 03, 2001 at 00:00

Friday, Aug 03, 2001 at 00:00
Thanks fellas for your help. I've since been told that an Engel works quite ok via the standard
cigarette lighter style socket as it does not draw as much as a Chescold. (Again this is second hand info
snd I still have not heard a direct answer from someone who uses a freezer.
My concern is that I already have radios (seperate 3 amp light wiing) and the van brakes/fridge (15amp) oming off
the second battery with independent fuses to the normal loom setup and I guess I can add another heavy
(say 15 amp wire) to run a fridge in the cargo area. It seems to me that this is putting a fair drag on the electrics
of the second battery. I'm assuming that the standard plug in the rear allows power to draw from both batteries
through the standard loom bit I'm concerned that if the wiring to the rear fitting is say only 6-8 amps and a fridge/freezer
draws too much more I'll burn out the factory wiring - at least that's the reasoning behind the question?
Whilst common sense would expect this wiring to allow for the power draw of all portable fridge
freezers it appears at least some vehicle makers may be saving a few cents and installing a token plug that is really only useful
for a light or compressor. The standard factory plug is now only live with the ignition on. I had an isolating switch (same one as the demister)
put in when they wired for the 12 v power to the van. This helps to ensure I turn off the power to the van if I stop for any long period on the road
as the 12v fridge in the would quickly flatten he battery. The manual states the rear socket is suitable only for 12 volt power or 120 watts maximum.

Thanks again, regards and happy touring - Ron H
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FollowupID: 242

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: Mike - Friday, Aug 03, 2001 at 00:00

Friday, Aug 03, 2001 at 00:00
Ron, I carry a 39L Engel in my 99 petrol jackaroo.For the small cost (as apposed to taking a chance on losing food or worse still, the beer getting hot,) I had a 6mm cable fitted from the aux battery to a hella plug in the cargo area. I had 2 outlets fitted at the same time so now leave the fridge connected while still being able to pump mattresses or run the fluro light. Having to turn off the fridge when the ignition is off seemed to defeat the purpose. I also had an auto cut-out(low volts)fitted to this line. Happy trails, Mike.
AnswerID: 839

Reply By: tim - Friday, Aug 03, 2001 at 00:00

Friday, Aug 03, 2001 at 00:00
Ron,
The standard able will run the fridge but it will heat up and become inefficent very quickly. You need to run minimum 4mm auto cable from you battery directly to the fridge and it will be problem free.
Tim
AnswerID: 840

Reply By: Graham - Saturday, Aug 04, 2001 at 00:00

Saturday, Aug 04, 2001 at 00:00
I cannot believe what I have just read in tony's response (response 5)
Under no circumstanses should you use standard three pin plug tops and sockets for anything other than 240 volts. What tony has infact manufactured with the 3 pin plug top connected to the cig. lighters is commonly referred to as a SUICIDE LEAD. A child or anyone for that matter grabs that lead and plugs it into a power point...NOT PRETTY. Back to the problem at hand. The standard socket config. has 2 possible probs. (a) the wiring is too light and (b) The socket cannot handle the current load. As said previously, install min. 6mm cable via an inline fuse and the best socket to use is a polarised (one pin vertical and one pin horizontal), two pin extra low voltage type. This system will ensure trouble free operation.
Cheers Graham
AnswerID: 844

Follow Up By: Dion - Tuesday, Aug 07, 2001 at 00:00

Tuesday, Aug 07, 2001 at 00:00
Graham, I gotta say I agree with you about suicide leads, quite nasty business. Cheers, Dion.
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FollowupID: 247

Reply By: Robert - Wednesday, Aug 08, 2001 at 00:00

Wednesday, Aug 08, 2001 at 00:00
Ron, I have a couple of outlets at the rear of the veichle. Since a near mishap through a electrical short, I always now fit a fuse at outlet to suit the use in addition to a fuse in engine bay. Safe motoring.
AnswerID: 859

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

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