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