Power for fridge

Submitted: Monday, Sep 10, 2012 at 13:23

Glenn M4

Hi All

I am going away and will have the fridge in the back of the car. Can i connect this to the 12v cigarette lighter to run whilst driving and not affect the car battery. Am i correct in saying that by using the cigarette lighter, the alternator will be recharging the car battery whilst driving. Once i stop i will then use a deep cycle battery to power the fridge. Are there other methods worth exploring.

Thanks

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AnswerID: 494637 Submitted: Monday, Sep 10, 2012 at 14:10

Ross M replied:

G'day Glenn MMMM
I hope we are talking about a compressor fridge with around 2 to 3 amp draw and not a 3Way fridge. If it is 3 way then this comment below isn't applicable because the draw will be 10 to 14 amps and requires more serious wiring setup.

Yes, you can use the compressor fridge that way and the car alt will keep it all charged and run the fridge too.
Be aware, because the cig plug is liable to shake with vehicle motion and become loose, it may disconnect the fridge without you knowing or just touch enough to cause a partial contact. If this happens then the contacting bits will become hot and melt the surrounding plastic of the plug.
Best to have something which positively l=keeps the plug in the socket to avoid this,eg Tape, Rubber band.
It is really best if the fridge has a plug which can take continual contact like a Merit plug or a small Anderson plug and these would be best run from the battery but that won't stop it flattening the battery if you leave it a while without charge.

PS a fully charged 100AH battery will run a compressor fridge in average conditions for about 1 1/2 to 2 days. Hotter the weather the shorter the charge life will be.

A 3way fridge on the same battery will last for about 6hrs if that.

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AnswerID: 494643 Submitted: Monday, Sep 10, 2012 at 16:37

Sea-Dog replied:

You are correct in saying that the alternator will recharge the battery as you are driving thus to me the drive time is counted as free fridge cooling time.. when you stop it sounds like you want to take a fully charged deep cycle with you to connect the fridge to for the duration of your camping trip.. and again there is nothing wrong with doing this if the deep cycle has enough amp hours to run the fridge for the duration.

The obvious fix for most people is to have a dual battery set up with power from the second battery to the fridge in the back and/or to run some solar cells to keep the deep cycle charged.

Each situation can be dealt with differently so maybe elaborate on whether you are looking to save money by simply bringing along a deep cycle that you have or whether you have x amount and want to commit to the best solution for your future needs ie, camping for 2 weeks at a time etc.

Also as said it is a compressor fridge isn't it? Those little cooler fridges aren't worth anything as they use heaps of power for very little cooling.

also when you set up your fridge on the deep cycle try to stay away from running the battery to an invertor to run on 240v if the fridge will work on 12v.. the invertor itself will also draw power so you get less run time from the battery. The best way is to run the 12v power direct to the fridge using the shortest run possible with lets say 6mm twin power lead to reduce power loss through the lead itself..

I am sure there is plenty of others with good knowledge that can help you out but most people would want more info on what you intend to achieve and your budget.

Cheers

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FollowupID: 770290 Submitted: Monday, Sep 10, 2012 at 19:01

Glenn M4 posted:

Thanks Seadog,

Yes the fridge is a 40l Engel. I do not have a deep cycle battery yet but was thiking of maybe getting one and then placing it in a Sidewinder Flyer so there are ready made connection points for the fridge and some lighting. I intend to also buy some solar panels to keep the Flyer charged. Does this sound OK or are there cheaper ways to go about it.

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FollowupID: 770299 Submitted: Monday, Sep 10, 2012 at 20:31

Holden4th posted:

Hello Glen

I recently did a trip to Perth and back from the Gold Coast using an Engel 40L fridge/freezer and also had two deep cycle batteries with me but I believe that one could do the trick quite easily. Those batteries were Waeco RAPS 36 a/h. I alternated them and recharged one each night from mains power via a 7 stage Projecta while the other ran the fridge i my car. This was probably overkill.

I am sure that you can run your fridge from your battery while driving and also recharge your deep cycle battery through cig lighter sockets without putting any undue strain on your car's electrical system. I've done this in the past and had no hassles. You won't quite get the depth of charge from your alternator that you would from a proper battery charger on 240 volts but you will certainly get enough.

What you put in your fridge also helps. The Engel 40L is a legend! I ran it on -1 degrees (about 2.3 on the dial). I put frozen cryovaced food on the bottom and built up from there. The frozen was still frozen 7 days later and my veggies at the top were nice and cold but still good and so was my beer. The most important thing is that my fridge was always full!

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FollowupID: 770322 Submitted: Tuesday, Sep 11, 2012 at 09:34

Sea-Dog posted:

G'Day again Glen

Yeah you can go a cheaper setup than that if you like but again it is a bit of a personal choice.

Myself I have a dual battery set up in the landcruiser. I have two Supercharge allrounder batteries which from memory are 105a/h each and are a bit of a hybrid starter battery which will stand a fair drain on the battery without killing it.
I have a Waeco 80 fridge in the back of the car and have had that there since 2005. I have had the batteries in the car for years now and have used the aux battery until flat many many times and it seems to still hold a pretty good charge (no doubt no where near as good as when new though)

So for me it was the dual battery set up with a couple of good batteries and then running some nice thick twin cable to the back where the fridge is and to a power socket at the back to plug into. My car is old school and so is the battery set up but to be honest it has never let me down over heaps of camping trips and four wheeling.

If you are likely to park the car for days on end then the battery will drain and the solar would be great but most trips the car is used daily which puts the charge back into the battery.. if I think that there is not enough driving I might let the car idle for a while just to give the battery a quick hit too.

This is probably the cheapest in the way of no fuss set ups but of course you can have a seperate battery with solar recharge unit or portable charging generator etc. all horses for courses.

The benefit of having the in-car set up is that the car will charge a battery a lot faster than solar etc... but this will bring you back to deep cycle battery or AGM battery etc as the deep cycle will generally not like to be hard charged.

There is HEAPS of info on the web about which batteries people prefer but for mine I have the 105a/h and it has done the job pretty nicely for my needs.

Cheers

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AnswerID: 494673 Submitted: Tuesday, Sep 11, 2012 at 07:20

KevinE replied:

Hi Glenn,

We ran a 3 way fridge off the 12v cigarette lighter socket on an 11,000 KM trip & never had any problems. We just unplugged it when we stopped & ran it on gas at night, whereas you'd be switching to the deep cycle battery at night. We keep our cool drinks in an esky, to avoid continually opening the fridge. We now have a 12v socket wired to the ignition, so we don't have to unplug it when we stop. We never had any issues with it not staying cool, even in the tropics. As has been said, keeping the fridge full helps to keep it cool.

Cheers,

Kevin.

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FollowupID: 770460 Submitted: Thursday, Sep 13, 2012 at 11:40

The Greta Bunyip posted:

I agree with Kevin. You don't need to go to extremes (& costs) to run a fridge while on the move. Our fridge runs off 12V, 240V or gas. My wife & I travelled around Australia (over 20,000kms) in 1998 & all we did was had a 12V cigarette lighter socket installed in the rear of our car. The fridge was the last thing we packed into the car when leaving a camp spot & the first thing we unpacked upon arrival, ensuring access without fuss. So even the fact the fridge was near the back window (& in direct sunlight) wasn't an issue in keeping things cold. We never had any trouble with plugs falling out either.