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portable fridge

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Thunderchild

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I've just bought one of those small camping/"lazy fat footballer fan can't be bothered to go to the fridge" mini fridges, it will run on 12 volts or off the mains with a built in SMPS (yes had the back off it already)

now on 12 volts it uses 45 W but running on the mains it uses 64 W !!! over 30% more, surely this cannot account for loses in the SMPS ? or maybe it can ? the SMPS outputs 12 volts so its not running the peltier cell at a higher voltage from the mains...

at present I have plans to change the noisy little fan (8 cm) for a nice 12 cm fan keep it cooler and QUIETER
 
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Yes, it probably uses a cheap Chinese SMPS which is only 70% efficient.

A full sized fridge uses less power than your little fridge, it's not very efficient.
 
well its a camping job so i'll have to make do, as is i'm going to dump the old and knackered 8 cm fan and replace it for a 12 cm fan striaght onto the heatsink, having thermostatic control would be nice as that way it could save power when it is not as hot
 
Are you basing this on watts or VA?

Sound like VA. The power supply probably has a power factor of about 0.6 so watts will be 0.6 VA with a some addition regulator loss in the power supply.
 
well it just says watts and if you think of it as a 65-70 % efficient SMPS then that adds up, anyhow i will run it on a 12 V leasure battery
 
I have a cooler box, it's rated at 65W 230VAC and 48W 12VDC, a whopping 73.8% efficient, like I said the SMPs is cheap Chinese crap.
 
Are these your measurements, or are they values taken from the name plate? There could be a de-rating factor regarding what can be written on the name plate.

The 12V input might not be bound by the same consumer protection rules?
 
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