portabe 12 v fridge freezer notworking on extention lead

Submitted: Friday, Jul 11, 2014 at 21:03
ThreadID: 108696 Views:3265 Replies:7 FollowUps:9
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Two months ago we purchased a 80 litres two compartment/two lid fridge freezer of the "Giant Power" brand.
This fridge freezer can be run as a two compartment fridge or as a fridge freezer.
This runs fine when plugged directly into the cigarette socket in the back of the 100 landcruiser series or when plugged into the mains when we are at a camp ground/powered site.
the trouble occurs when we are free camping in the bush. I purchased a 10 metres cigarette plug type extension lead with a 14 amp fuse but when we plug this from the caravan into the fridge/freezer it does not kick in. The caravan has two x 105 amp batteries. Power is getting to the fridge/freezer as the display lights up.
The display on the fridge/freezer shows 12.5 volts going into it when on the extension lead( but fails to run). When plugged directly into the cigarette lighter plug at the back of the cruiser it shows 11.0 volts (and is running fine)
Any help would be appriciated. It is doing my head in. Currently at Gascoine River and about to attack the Great Central Road. Many thanks, cheers, Case
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Reply By: olcoolone - Friday, Jul 11, 2014 at 21:16

Friday, Jul 11, 2014 at 21:16
Has the fridge got a battery monitor system that will cut the fridge out a certain voltages to save the battery, there may be a voltage drop over that length of cable.

The 12.5 would be a no load voltage and with a load it may drop.
AnswerID: 535920

Follow Up By: caseh - Friday, Jul 11, 2014 at 21:23

Friday, Jul 11, 2014 at 21:23
thanks for the quick reply. auto electrician tested the extension lead and confirms there is no voltage drop in the lead. the lead was purchased at auto electrician in Broome. 14 amp. not a home made job. thanks for taking the time to reply. voltage cut out has been set at 10,5 v.
FollowupID: 819872

Follow Up By: The Bantam - Saturday, Jul 12, 2014 at 09:27

Saturday, Jul 12, 2014 at 09:27
Sorry but there is ALWAYS voltage drop..its a matter of how much.

Lets start with the ciggerette lighter socket.

Is this an actual cigearette light or a factory fitted accessory socket that looks like one or an accessory socket that has been installed specifically for the purpose.

The cigarette lighter sockets themselves are not a clever item, they are notorious for poor contact quality and the best of them are rated at 15 amps maximum...and they are not happy things at that.

problems with cigarette light sockets and fridges are the norm rather then the exception....they where not originally designed as an accessory socket.

moving on to where this "cigarette lighter" socket is and how it is wired.

If it is an actual "cigarette lighter" it will probably be wired to a 15 amp fuse ( maybe a 10 in some modern cars) and in the dash with a fairly short length of wire......think about this for a minute..an actual ciggy lighter will draw its 15 ish amps for about 30 seconds before it pops out...that is the limit of the design.

If it is an accessory socket that looks like a cigarette lighter.....it may not be designed to support much load to start with...a couple of the ones I have seen are protected my a 10 amp fuse or less.

they realy are intended for charging mobile phones running sta nav and other fairly light loads..and they are not wired in particularly heavy wire to start with.

so if we have a factory fitted accessory socket..it might be marginal to start with.

Then we look at the 10 meter extension cable.

If we are working with a 12 volt nominal supply, voltage drop is ever present...there is always voltage drop.....we only have 12 volts and if only one or two of those volts go missing stuff stops working or works badly.

If wiring a ciggy socket ( or something to fill the same function) in the rear of a vehicle.....we need to be looking at 6mm automotive wire as a minimum over the approximately 5 to 7 meters involved...that is 4.5mm2 or 50 amp cable.

This extension cord is 10 meters...that is a long way in 12 volts.
Using 6mm ( automotive) or 50 amp cable would be the minimum I would entertain.

If this cable has been made up on 4mm automotive or 15 amp cable, it does not surprise me you are having problems.
If this cable is 4mm automotive twin..it will be about 4mm x 7mm dimension in the jacket....6mm automotive twin will be about 6mm x 10mm dimension in the jacket.

In electrical design in 12 volt systems the actual amp rating of the cable is only significant in very short lengths of cable....everything revolves arround voltage drop and using heavy cable to combat it.

so think about this for a moment..if you are connected to a socket in the rear of the vehicle, and a 10 meter extension cord..you will be running about 15 meters of cable back to the battery, pluss the poor contacts in two sets of ciggy sockets.

I don't need to do any calculation or measurements to expect to see problems.

If the fridge motor wont start...I don't know how the autoelectrician measured the voltage drop on load.

Serioulsy....unless you want to fit a purpose made accessory socket ( and probably not a ciggy socket) and have a pretty heavy extension cable made...forget the idea of an extension cable and leave the fridge in the car.

FollowupID: 819900

Follow Up By: The Bantam - Saturday, Jul 12, 2014 at 09:35

Saturday, Jul 12, 2014 at 09:35
Now adding to what I have already posted in relation to the original post.

The fridge while running direct in the vehicle shows 11 volts....hell there is 1.5 volts of voltage drop already.

the display shows 12.5 volts when connected to the extension cord....but the motor refuses to run...so that measurement is not under load.

I suspect the low voltage cut out in this machine is 10.5 volts and you would be easily picking up an extra half a volt or more of voltage drop on the cable.

your fridge running by the skin of its teeth while plugged directly into the vehicle.......quite a few fridges would not run at all in this situation.

SO..as has been mentioned..start the vehicle and see what the voltage readings are...you may find with 13.8 or 14.2 volts of supply from the alternator the fridge might run on the extension cord....but then again there may even be too much voltage drop in the chain for that.

FollowupID: 819901

Follow Up By: The Bantam - Saturday, Jul 12, 2014 at 09:40

Saturday, Jul 12, 2014 at 09:40
Looking on the web..among the scant information about this fridge.
The low voltage cut out is 10.8 volts.

Mate ya fridge is barely running even in the car.

On the excension cord without the engine running..forget it.

FollowupID: 819903

Follow Up By: olcoolone - Saturday, Jul 12, 2014 at 10:00

Saturday, Jul 12, 2014 at 10:00
Did the auto elect test it under load or just simple removed the plug from the fridge; tested it and said "there is no voltage drop" or did he do it properly by placing the wiring as a whole under load.

Things operate differently under load.

And as for cigarette plugs and sockets..... they should be outlawed under the UN for danger to humanity, they are the biggest cause of headaches and problems but for some stupid reason many think they are the best.

FollowupID: 819907

Follow Up By: Shaker - Saturday, Jul 12, 2014 at 11:20

Saturday, Jul 12, 2014 at 11:20
Caseh, take the advice that you asked for, if it works without the extension lead & doesn't work with it, logic says it's the lead causing the issue!
FollowupID: 819918

Reply By: Ross M - Friday, Jul 11, 2014 at 21:26

Friday, Jul 11, 2014 at 21:26
Because of the start up and running load of the fridge it possibly won't work due to the long extension lead acting as a resistance and dropping the voltage when it tries to start.

10 metres of cable WILL definitely hold back current flow and far less length may possibly make it run OR use large sized cable.

Overall you will be far better of with by using small Anderson plugs to supply the fridge instead of ciggy type plugs and sockets. "Ciggy" are not good at providing, a connection with good integrity, because they only touch at a small point which relies on the tight fit to hold the plug in position. If they work loose the contact becomes hot because of resistance and that further erodes any performance you may get out of them.

Ciggy OK for a visit to the shops, but long term use and also with extensions, it should be large cable and decent plugs/sockets like Anderson do provide.
AnswerID: 535921

Reply By: MEMBER Bushbum - Saturday, Jul 12, 2014 at 07:24

Saturday, Jul 12, 2014 at 07:24
perhaps you could check the polarity of the extension lead?
regards, Bushbum
AnswerID: 535932

Follow Up By: Ross M - Saturday, Jul 12, 2014 at 12:53

Saturday, Jul 12, 2014 at 12:53
I agree with Athol, the Toyota wiring to the plug in the rear is very very likely to be strangling the amps flow at the best of times by having the wires far to small in the loom. It is fed from the front as it is so the total length from battery to fridge at the end of an extension would be around 14 metres at the very minimum.
12v pressure of "Electricity" will only "drip out" without a BIG cable all the way.
FollowupID: 819937

Reply By: gbc - Saturday, Jul 12, 2014 at 08:38

Saturday, Jul 12, 2014 at 08:38
In the short term, see if the fridge fires on the extension lead with the engine running. As stated it is most probable that the initial startup requirement of the fridge is more than the plug setup can handle, especially if you are running the extension from one of those factory supplied cigarette outlets in the vehicle. You could then remove the cig plugs, cut the lead and make a short extension straight off the battery with shielded female spade bit connectors and leave that permanently wired into the battery. Put a couple of male spades onto the rest of the lead and use that as your extension joining point. Do what Manu does with the frozen frozen risotto and throw the ciggarette plugs out the door. I would also get rid of the fridge plugs at the other end and go back to spade/Andersen connectors at that end for reliability but others like to be able to retain the ability to plug them in anywhere. I have seen too many plugs work loose on corrugations and spoil food/beer = ugh.
Anyway just a couple ideas to maybe help you finish the trip with cold beer.
AnswerID: 535936

Reply By: Athol W1 - Saturday, Jul 12, 2014 at 09:24

Saturday, Jul 12, 2014 at 09:24
Whilst I agree with all the other comments, and especially those regarding the use of ciggy plugs and Anderson plugs, may I also suggest trying the extension lead from the vehicle socket so as to eliminate any fault/problem with the extension lead. Be aware that the combined length of the extension lead AND the lightweight wiring that Toyota use for their ciggy socket can still give sufficient voltage drop to have an effect on your fridge operation.

Also it would not be the first time that a van manufacturer has reversed the wiring to a 12 volt outlet so check that its polarity is correct.

Hope this helps and have fun with your travels
AnswerID: 535941

Reply By: Member - liftnlock lux - Saturday, Jul 12, 2014 at 17:50

Saturday, Jul 12, 2014 at 17:50
Hook up a pure sine wave inverter and run a 240v leed. The inverter and 240v extension would probably cheaper than the 12v leed on it's own..Good luck
AnswerID: 535968

Follow Up By: oldtrack123 - Thursday, Jul 24, 2014 at 22:38

Thursday, Jul 24, 2014 at 22:38
Yes, by all means get an inverter & take the risk of possible electrocution!!
Why this craze for inverters to overcome a simple problem like voltage drop??


FollowupID: 820683

Reply By: caseh - Thursday, Jul 24, 2014 at 21:19

Thursday, Jul 24, 2014 at 21:19
Thanks all for taking the time to reply and for your valuable input.

I have not replied earlier as we have only just come off the red dirt and are back having coverage.
The ciggy plugs will be changed to Anderson plugs and I will check for voltage drop in the first instance.
Great forum and I do appreciate the replies.

AnswerID: 536533

Follow Up By: oldtrack123 - Thursday, Jul 24, 2014 at 22:42

Thursday, Jul 24, 2014 at 22:42
JUst rememberwhen doing that voltage drop test the CIRCUIT must have the load on it switched on & RUNNING
If the load [fridge] is not switched on a & running a voltage tests means absolultly nothing!!!

FollowupID: 820684

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