 | Home > In Car Electronics > ARB 47l fridge fuse |
 
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| zone30 Member Since: 07 Sep 2012 Location: Gent Posts: 669   
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5.1 seems a lot! Drains a 90Ah battery in Less then a day while I expect it should be able to run at least 3 days.
Shure it 5.1A? |
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23rd Jul 2014 7:56pm |
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| Riyo Member Since: 26 Jun 2014 Location: Aberdeen Posts: 89  
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its on the rating plate at the back of the fridge and doesnt sound much at 12v to me. The compressor only has to run when it needs to cool down the fridge approx 10%ish of the time so average current draw is in the region of 1A,
5.1A@12v = 60W On a odyssey 1500 68ah not drawing down the battery down by more than around 40-50% that gives around 30hrs before the battery is down to around 50-60% and needs topping which is fine. What i dont get is if its a 4A fuse why doesnt it blow when the compressor turns on and draws 5.1A... i must be missing something here |
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23rd Jul 2014 8:02pm |
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| Paddie42 Member Since: 24 Apr 2014 Location: Hamphire Posts: 230  
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Is it normal running current or starting current? A DC motor draws (from memory) about 4 or 5 x normal running current when starting for a very small amount of time. The time at this higher current isn't long enough to heat the fuse to blow.
Just a thought.... |
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23rd Jul 2014 8:50pm |
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888 
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Most fuses will not blow immediately at their rated value, it takes a sustained over current (or a very much bigger one) to blow them. A 4A fuse will normally take at least 8A to blow it immediately and the likelihood is that with a 5A startup draw the current won't last long enough to actually blow the fuse. Once it's got started the current drops quickly so the sustained current draw will be lower than 4A. I measured the normal draw on our fridge a year or so ago and seem to remember it being in the region of 1.8A when it was running.
We have one of those fridges in the back of the 90, a single Odyssey 1500 will run it for at least 48 hours, even when it's over 30 degrees outside. http://www.yorkshireoffroadclub.net/ |
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23rd Jul 2014 8:52pm |
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| Riyo Member Since: 26 Jun 2014 Location: Aberdeen Posts: 89
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ok thanks, good to know.
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23rd Jul 2014 8:58pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578 
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The fuse inside the fridge is a 4 amp fridge.
The average current consumption of the ARB 47 is 0.87 amps/hr. I do not know the start up current of the fridge. A lot of figures refer to 12 volts whereas the nominal voltage of a car battery fully charged is 12.6 volts so current figures will change. Have used one for years, both on 12 volt and 240 volt and never managed to blow the fuse yet! Brendan |
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23rd Jul 2014 9:06pm |
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| zone30 Member Since: 07 Sep 2012 Location: Gent Posts: 669
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0.87A sounds a lot better then 5.1A. That's approx 4 days on a 90Ah battery.
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25th Jul 2014 1:45pm |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610 
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Start up current is normally factored at 6 x for large motors that is why you have B, C and D type circuit breakers. D being the one with the highest starting current curve for heavier applications. Domestic in most cases they will all be B.
'Diversity' is the key here. For example if you have an electric cooker and individually add up all the individual heater elements the total current draw will be far in excess of the 40 amp rating of your breaker or fuse. Why protect it with only a 40 then? Simply because with the thermostats switching in and out it will never draw the maximum amount. Same as a fridge, freezer or air conditioning unit, it has the maximum capacity if conditions are severe to draw in excess of the fuse that is protecting it. However in normal operating conditions it will not! If you have a failing unit by protecting it with the maximum fuse possible you will have no advance notice either before possible catastrophic failure. This is 'Diversity' in simple electrical terms. You can also get slow blow, anti surge and quick rupture fuses the slow blow or anti surge are normally discernable by having a coiled element or an element suspended in a medium such as sand or porcelain powder. They also can be labelled with a '(T)' on the fuse. If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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25th Jul 2014 2:23pm |
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