Car Fridges

Submitted: Monday, Sep 16, 2002 at 00:00
ThreadID: 1989 Views:1566 Replies:7 FollowUps:2
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What is meant by "minimum voltage protection" in regards to fridges?
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Reply By: Member - Mal - Monday, Sep 16, 2002 at 00:00

Monday, Sep 16, 2002 at 00:00
Ron, My understanding is that there is a cut out device when the battery voltage drops to the lowest level that the fridge motor will run at without being damaged. It is usually about 10.5 volts. Mal Try.
AnswerID: 6658

Reply By: Member - Nigel - Monday, Sep 16, 2002 at 00:00

Monday, Sep 16, 2002 at 00:00
Yep Mal's right. The cutout is to protect the compressor, not the battery.

It's best to avoid getting a battery that low, as it will reduce the life of any battery, severely in the case of a starter battery.
AnswerID: 6662

Reply By: nickycohen - Wednesday, Sep 25, 2002 at 00:00

Wednesday, Sep 25, 2002 at 00:00
If the battery voltage falls below a certain level, the fridge will switch off. It protects the battery.
AnswerID: 6904

Follow Up By: Ron - Wednesday, Sep 25, 2002 at 00:00

Wednesday, Sep 25, 2002 at 00:00
It's starting to get confusing. If it's to protect the compressor, what's the use ? as it's not a lot of demand to ask for, down to 10.5 volts from 14 volts at most. If it's to protect the battery, then again, it's not a lot of ask before shutting down. Am I correct in thinking that it would not take a lot of demand in time, for a fridge to reduce battery voltage to approx. 10.5 volts ?
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FollowupID: 3124

Follow Up By: Coops - Sunday, Sep 29, 2002 at 00:00

Sunday, Sep 29, 2002 at 00:00
Engel's cut out switch comes in to effect way too late to help your battery and you need to look at an alternate device for battery preservation.
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FollowupID: 3180

Reply By: Member - Nigel - Thursday, Sep 26, 2002 at 00:00

Thursday, Sep 26, 2002 at 00:00
The time taken to reduce a battery from full charge to flat is entirely dependent on the average amp draw of the fridge and the Amphour (Ah)capacity of the battery.

The average 4WD starter battery has an Ah rating between 40 and 60 Amphours, but the very design of starter batteries means that every time you flatten them you severely reduce there life.

The solution: never go below 12 volts or get a deep cycle battery. My 95 Ah deep cycle can run my 68 litre EvaKool fridge for 3 days and two nights (in FNQ) and still have 11.5 volts (measured with the fridge off). I always try and avoid discharging below 11.5 volts for two reasons: 1. So I can assist my starter battery if something unexpected happens, and 2. the shallower the discharge the longer the battery life (even with deep cycles).
AnswerID: 6969

Reply By: Mark - Friday, Sep 27, 2002 at 00:00

Friday, Sep 27, 2002 at 00:00
Ron, Nigel is right, it depends on the size of the battery. Look at the amount of current a fridge uses in a 24hr period rather than amps per hour. The 10.5vlts is to save the compressor and electronic unit associated with it as even with the the compressor running with a low voltage battery it will not be running properly. 10.5vlts will start the car (perhapes).
AnswerID: 6986

Reply By: Member - Nigel - Saturday, Sep 28, 2002 at 00:00

Saturday, Sep 28, 2002 at 00:00
I certainly wouldn't like to have to rely on a battery at 10.5 volts to start my 4WD. BTW it's interesting that most battery manufacturers state that a battery is fully discharged at 11.89 volts (measured with no load applied).

Load affects the voltage reading, so it's best to wait at least half an hour after a load is removed to test what state of charge your battery is in. The voltage should also continue to rise (slightly) over a 24 hour period as the acid solution stabilises.
AnswerID: 7013

Reply By: colin - Monday, Sep 30, 2002 at 00:00

Monday, Sep 30, 2002 at 00:00
cheaper and easier to replace a batterie than to try and repair a fridge in the outback. Col
AnswerID: 7058

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