Whynter refrigerator just about killing my battery after 12 hours

[ducktapeguy]

I have a whynter 45 and it usually has no problem running a day or two on a group 35 battery in Normal conditions. I have a separate battery pack powering the fridge with watt meters measuring the input and output power draws so I’ve taken measurements on exactly how much energy the fridge uses. The whynter energy usage chart is pretty accurate in my experience. In typical use the fridge will cycle between 20-70%, but there are a lot of different factors that affect it.

During the cool down period, it’s running at 100% duty cycle, so you can see energy use as much as 1400 wh/day. With pre chilled contents in cool weather it can be as little as 100wh/day. The biggest variable is whether your using it as a fridge or freezer. Trying to freeze items takes a LOT of energy. If you set your fridge at 32 degrees, it’s actually cycling between abut 29-36 s you may be seeing some high energy usage because it’s trying to partially freeze some of the contents. Try setting at 34 degrees and the power draw may drop quite a bit.

 

[67cj5]

I have a whynter 45 and it usually has no problem running a day or two on a group 35 battery in Normal conditions. I have a separate battery pack powering the fridge with watt meters measuring the input and output power draws so I’ve taken measurements on exactly how much energy the fridge uses. The whynter energy usage chart is pretty accurate in my experience. In typical use the fridge will cycle between 20-70%, but there are a lot of different factors that affect it.

During the cool down period, it’s running at 100% duty cycle, so you can see energy use as much as 1400 wh/day. With pre chilled contents in cool weather it can be as little as 100wh/day. The biggest variable is whether your using it as a fridge or freezer. Trying to freeze items takes a LOT of energy. If you set your fridge at 32 degrees, it’s actually cycling between abut 29-36 s you may be seeing some high energy usage because it’s trying to partially freeze some of the contents. Try setting at 34 degrees and the power draw may drop quite a bit.

You say that chart is pretty accurate, but they quote 12.5 hours pull down time that seems excessively high from 77*f down to 39.2*f, and at 1.2 or 1.4kw that is an awful lot of power, even my domestic fridge freezer only use's 987 to 1068watts per 24 hours on it's worst setting, surely those chart figures have to be wrong,

The Idea of a 4x4 fridge is to be portable and run on very little power but according to your post it is using 40% more power per 24 hours than a domestic fridge ?. and that is almost double what my 47L uses in 3 days 6 hours or 78 hours.

 

[DaveInDenver]

The Idea of a 4x4 fridge is to be portable and run on very little power but according to your post it is using 40% more power than a domestic fridge ?.

I can only offer a comparative opinion but I am not surprised to hear a portable fridge is significant less efficient than a domestic fridge. Particularly on AC, where I suspect they would be even worse if for no other reason than I assume the manufacturer is going to use a power supply that is only just efficient and expensive enough to run the compressor without damaging it.

My Engel MT45 draws right at about 2 amps running on DC (measured at 13.8 V). I've not measured to verify but Engel specify it draws 0.7 A on 120 V power, which would mean it consumes 84 watts on AC compared to 28 watts on DC.

 

[67cj5]

I can only offer a comparative opinion but I am not surprised to hear a portable fridge is significant less efficient than a domestic fridge. Particularly on AC, where I suspect they would be even worse if for no other reason than I assume the manufacturer is going to use a power supply that is only just efficient and expensive enough to run the compressor without damaging it.

My Engel MT45 draws right at about 2 amps running on DC (measured at 13.8 V). I've not measured to verify but Engel specify it draws 0.7 A on 120 V power, which would mean it consumes 84 watts on AC compared to 28 watts on DC.

Yeah Dave, I'm with you on this, I have measured mine at 1*c steps from 4*c/39.2*f and lower right down to -18*c/-0.4*f on the dial, so this is a Head Scratcher for sure.

My ARB is using 9.375watts per hour. when set to 4*c/39.2*f as per Whynter's Chart.

 

[ducktapeguy]

I don’t know how they calculate pull down time, but with a fridge semi full of water that’s probably about right. I know before a trip I usually pre load my contents a few days ahead of time and pre freeze things, it takes at least a day or so before things get to temp. With an empty fridge it goes down fairly quickly, I measured it one time but I think it can go from 80f to 30 f less than an hour.

Bringing things down to temperature and maintaining temperature are two different things. Water has a lot of heat capacity, so it takes a lot of energy to cool it. Once it’s cool, the amount of energy to maintain that temp is just a matter of how good the insulation of the fridge is. If you look at the whynter chart, to maintain 0.4f temp in 109f ambient is about 1.3kwh, so less efficient than some others but not that horrible.

 

[67cj5]

I don’t know how they calculate pull down time, but with a fridge semi full of water that’s probably about right. I know before a trip I usually pre load my contents a few days ahead of time and pre freeze things, it takes at least a day or so before things get to temp. With an empty fridge it goes down fairly quickly, I measured it one time but I think it can go from 80f to 30 f less than an hour.

Bringing things down to temperature and maintaining temperature are two different things. Water has a lot of heat capacity, so it takes a lot of energy to cool it. Once it’s cool, the amount of energy to maintain that temp is just a matter of how good the insulation of the fridge is. If you look at the whynter chart, to maintain 0.4f temp in 109f ambient is about 1.3kwh, so less efficient than some others but not that horrible.

Yeah their figures do seem a little crazy, It's a quality fridge so it has to be better than that, I think they lost it somewhere in translation is all.

 

[ducktapeguy]

Yeah Dave, I'm with you on this, I have measured mine at 1*c steps from 4*c/39.2*f and lower right down to -18*c/-0.4*f on the dial, so this is a Head Scratcher for sure.

My ARB is using 9.375watts per hour. when set to 4*c/39.2*f as per Whynter's Chart.

I’m curious to know, what is the ambient temperature when you have it set to 39f? I’ll have to see if I recorded my temperature and power draws, but I think the whynter averages about 320wh/day in 80f ambient when set to 37f, or roughly a little over 1.1 amp/hour average

 

[luthj]

These units have efficient compressors, but due to space constraints they have fairly poor insulation compared to high efficiency home units (measured by watts/hr/cubic foot). Only a handful (like engle platinum) have really thick insulation. Some of the really efficient euro-grade mini fridges are efficient enough to justify installing a small inverter to power them. (inverter switched with thermostat).

 

[67cj5]

I’m curious to know, what is the ambient temperature when you have it set to 39f? I’ll have to see if I recorded my temperature and power draws, but I think the whynter averages about 320wh/day in 80f ambient when set to 37f, or roughly a little over 1.1 amp/hour average

At 72 to 80*f it is drawing about 0.53 to 0.599 amps, in cooler temps of 65*f it will use as little as 0.43 amps, and it only does 8.7 on/off cycles per 24 hours when loaded a 1/3rd full.

hope that helps.

 

[ducktapeguy]

At 72 to 80*f it is drawing about 0.53 to 0.599 amps, in cooler temps of 65*f it will use as little as 0.43 amps, and it only does 8.7 on/off cycles per 24 hours when loaded a 1/3rd full.

hope that helps.

Thanks. It's no surprise the ARB is more efficient, but it's nice to have some numbers to compare.

 

[67cj5]

Thanks. It's no surprise the ARB is more efficient, but it's nice to have some numbers to compare.

Where this all gets confusing is we all know that 99% of these fridges use the exact same compressor and they all have similar wall thickness yet some perform better than others, I for one have always thought that "Oh it has a Danfos Compressor" so it's going to be as good as it gets but clearly that is not the case because the 47L/50QT ARB uses about 0.56 to 0.58+/- amps at 80*f and the 63L/65QT ARB all weather uses 0.638 Amps at 80*f and the CFX50 uses 0.92 amps And the Engle Legacy MT40 uses 0.937 amps etc etc, So buying the right fridge is a minefield,

 

[DaveInDenver]

Engel fridges don't use Danfoss compressors, they have Sawafuji compressors. The motor/compressor is supposed to be robust and easy starting since it is a simpler design. It's more like a linear shaker than a rotating compressor, the piston is driven back and forth using a bunch of springs.

I can't say it's really better or not in longevity or performance since I have nothing to compare against, but that's the theory anyway. I can say it does start up without much in rush.

 

[DaveInDenver]

 

[67cj5]

Engel fridges don't use Danfoss compressors, they have Sawafuji compressors. The motor/compressor is supposed to be robust and easy starting since it is a simpler design. It's more like a linear shaker than a rotating compressor.

I can't say it's really better or not in longevity or performance since I have nothing to compare against, but that's the theory anyway. I can say it does start up without much in rush.

Yeah Dave I grew up with Engel, and I was going to buy the Engel MT45 but the dealer did not return my calls so I went with ARB, Both being Aussie products they are as good as it gets,, I also looked at NL but they are power hogs even though they have nigh on 3" of insulation,

I have been doing more tests on my fridge and at 08:35 this morning it had just finished it's "ON" cycle when set @0*c/32*f so then I up the Temp to 2*c/35.6*f in an Ambient temp of 17.3*c/63.14*f, By raising it by 2*c it took 8 hours 2 minutes to turn it's self back on So it only lost/warmed up by 2*c or 3.6*f in 8 hours so I would say that it is very thermally efficient, judging by those figures.

 

[DaveInDenver]

@67cj5, I have noticed that portable fridges benefit from tailoring your use. Being careful to open slowly to not disturb the air, for example. There's nowhere for the air to go once it settles, no seal to leak like a domestic fridge door. I have a transit bag on mine, with the reflective liner, and that seems to also make a significant improvement.