Whynter refrigerator just about killing my battery after 12 hours

[67cj5]

No. If the fridge is stabilized (steady state) adding a bottle of water etc will increase the cooling load by the amount I calculated. Obviously you have the existing cooling load + 22 watt-hours. This energy usage (about 8 watt hours of electricity) will be spread out over an hour or two. It is a specific and easily calculated value. I work with this type of stuff for a living, this is an engineers bread and butter really.

The whole purpose of this exercise in physics is to describe/define the size of various factors on a fridges cooling load. As described above air loss is a minor impact on cooling load for fridges that are not opened and closed constantly.

A fridge is system, in physics energy in minus stored energy must equal energy out.

Yeah I agree, Only trouble "most" physics relates to and Ideal world set of figures where as we live/operate in a varying world of physics So although we could both have the same fridge we both could end up with a different set results,

One thing for sure although these fridges use less power than our domestic freezers they appear to have a lot more cooling power IE I put a drinking glass of water in there that measured 5" by 2.5" straight out of the water tap and it froze it in about 1 hour 50 minutes and it will make 2.5"square X 1/2" think Ice blocks in about an hour +/-

 

[OpenTrackRacer]

Fridge ran for 15.5 hours overnight and the Jeep started right up. Battery was at 12v which is a little lower than I'd like but doable. Putting the fridge on a Ah meter now for a 24 draw test with the same contents.

 

[OpenTrackRacer]

Just finished a 24 hour run. The fridge had one gallon of water in it and nothing else and kept a temperature between 33 and 35 degrees. Consumption was 417 watt hours, which is about 28% more than Whynter's spec (325 watt hours). My fridge was set a little colder but I'm not sure that would make a 28% difference. I had the power supply set to 12.5v so it took 33Ah.

I'll probably do another test out of curiosity when I have time with the fridge fully packed.

 

[67cj5]

Just finished a 24 hour run. The fridge had one gallon of water in it and nothing else and kept a temperature between 33 and 35 degrees. Consumption was 417 watt hours, which is about 28% more than Whynter's spec (325 watt hours). My fridge was set a little colder but I'm not sure that would make a 28% difference. I had the power supply set to 12.5v so it took 33Ah.

I'll probably do another test out of curiosity when I have time with the fridge fully packed.

Well done, Not that much of a difference, A 3 or 4*f difference would make about a 3 to 15 variation, 2 days ago I started a 10 day test set at 2*c which is about 33.6*f and it is using on average of 10.14 watts per hour or about 247watts per 24hrs, If I raise it by 2*c to 4*c/ 39*f it uses 225watts per 24hrs.

 

[ducktapeguy]

Anytime your near the freezing point the consumption is going to vary wildly. Set at 29 degrees with a full load of water and mine will run near continuously and use up to 1400wh/day because it’s trying to freeze the water. Set at 35 and it’s anywhere between 200-400 wh. Conversely if the water is frozen and set to 35 degrees and it’ll use almost no power unti ice melted. That’s probably why whynter specs are taken at 10f and 39f, well away from the freezing point.

It seems like other people have taken similar measurements. It would be intereting to do a standard test of different fridges/freezers and compare energy usage numbers.

 

[67cj5]

Anytime your near the freezing point the consumption is going to vary wildly. Set at 29 degrees with a full load of water and mine will run near continuously and use up to 1400wh/day because it’s trying to freeze the water. Set at 35 and it’s anywhere between 200-400 wh. Conversely if the water is frozen and set to 35 degrees and it’ll use almost no power unti ice melted. That’s probably why whynter specs are taken at 10f and 39f, well away from the freezing point.

It seems like other people have taken similar measurements. It would be intereting to do a standard test of different fridges/freezers and compare energy usage numbers.

Set at 29* to 35 * mine is using around 245watts and that will rise to 247watts per day, Even maxed out I have never seen it go above 500w. Around 497 is the most I have recorded.

 

[ducktapeguy]

Set at 29* to 35 * mine is using around 245watts and that will rise to 247watts per day, Even maxed out I have never seen it go above 500w. Around 497 is the most I have recorded.

Im guessing it probably depends on the temperature calibration of each fridge, thermistor location, and the on/off setpoints. 35 degrees on one fridge may be 28 on another. Whynter spec on DC is 65w, mine runs pretty close to that. When set below freezing with a load of unfrozen water it basically runs continuously, so 65wx24hours is 1560 wh. At 29f may cycle on/off at 25/32 but will mostly stay on until the water freezes then cycle normally.

Interestingly, when I tested a full load of water from 60f to 0f, the temp readout will ramp down to 25 and level off there until all the water is frozen, then reach 0. Since freezing point of water is a well known constant, I assume my temp readout has a 7 degrees offset from actual. I think that would be a pretty good standard test to compare fridges. Freeze a couple gallons of water and measure the energy and time required. That would eliminate the temp reading differences between brands and compare efficiency of each.

 

[67cj5]

Probably depends on the temperature calibration of each fridge, thermistor location, and the on/off setpoints. Whynter spec on DC is 65w, mine runs pretty close to that. When set below freezing it basically runs continuously so 65wx24hours is 1560 wh. At 29f may cycle on/off at 25/32 but will mostly stay on until the water freezes then cycle normally.

Interestingly, when I tested a full load of water from 60f to 0f, the temp readout will ramp down to 25 and level off there until all the water is frozen, then reach 0. Since freezing point of water is a well known constant, I assume my temp readout has a 7 degrees offset. I think that would be a pretty good standard test to compare fridges. Freeze a couple gallons of water and measure the energy and time required. That would eliminate the temp reading differences between brands and compare efficiency of each.

Yours can't be using 65w because that is the per hour rating, 65w divide 60 minutes = 1.08333333333 watts per minute, If it runs for 14m 18 seconds, that's a total of 15.491666666watts per hour , Now you have that figure you now need to time it's off cycle then add them together and then work out what it does over a 24 hour period. then you will have your correct wattage.

 

[luthj]

Yours can't be using 65w because that is the per hour rating, 65w divide 60 minutes = 1.08333333333 watts per minute, If it runs for 14m 18 seconds, that's a total of 15.491666666watts per hour , Now you have that figure you now need to time it's off cycle then add them together and then work out what it does over a 24 hour period. then you will have your correct wattage.

You are misunderstanding the difference between power and energy. Power is instantaneous, watts. Energy is power acting over time. watts x hours =watt-hours. Not watts divided by hours (watt/hours).

65 watts is a typical power consumption (rate) for one of these fridges. Over an hour that would be 65 watt hours. Think of your electricity bill, you are always billed for the number of kilowatt hours you consume.

The same goes for amps its not amps/hours its amp-hours per hour.

 

[ducktapeguy]

Yes, 65w/hour. IF it cycles on/off then I’d multiply it by the duty cycle %, but if I have the temp set well below freezing with a load of water, what I was trying to explain was that it won’t cycle, it’ll stay on 100% of the time, until all the water is frozen. The latent heat of water will prevent the fridge from going below that point until all the water is frozen.

 

[67cj5]

Probably depends on the temperature calibration of each fridge, thermistor location, and the on/off setpoints. Whynter spec on DC is 65w, mine runs pretty close to that. When set below freezing it basically runs continuously so 65wx24hours is 1560 wh. At 29f may cycle on/off at 25/32 but will mostly stay on until the water freezes then cycle normally.

Interestingly, when I tested a full load of water from 60f to 0f, the temp readout will ramp down to 25 and level off there until all the water is frozen, then reach 0. Since freezing point of water is a well known constant, I assume my temp readout has a 7 degrees offset. I think that would be a pretty good standard test to compare fridges. Freeze a couple gallons of water and measure the energy and time required. That would eliminate the temp reading differences between brands and compare efficiency of each.

Yours can't be using 65w because that is the per hour rating, 65w divide 60 minutes = 1.08333333333 watts per minute, If it runs for 14m 18 seconds, that's a total of 15.491666666watts per hour , Now you have that figure you now need to time it's off cycle then add them together and then work out what it does over a 24 hour period. then you will have your correct

You are misunderstanding the difference between power and energy. Power is instantaneous, watts. Energy is power acting over time. watts x hours =watt-hours. Not watts divided by hours (watt/hours).

65 watts is a typical power consumption (rate) for one of these fridges. Over an hour that would be 65 watt hours. Think of your electricity bill, you are always billed for the number of kilowatt hours you consume.

The same goes for amps its not amps/hours its amp-hours per hour.

I have worked it out using maths and I also have it plug in to a meter and set to 4*c/39*f it uses 225 watts per 24 hours, divide the 225 by 24hrs = 10.04 watts per hour.

That 65w is an hourly rating and you con only count the minutes it is running for. If it was running for the whole hour then that would be 65 watts but you have to include the off time.

 

[67cj5]

Yes, 65w/hour. IF it cycles on/off then I’d multiply it by the duty cycle %, but if I have the temp set well below freezing with a load of water, what I was trying to explain was that it won’t cycle, it’ll stay on 100% of the time, until all the water is frozen. The latent heat of water will prevent the fridge from going below that point until all the water is frozen.

Well what should happen is that it should run for about 25 to 40 minutes-ish and then it should shut off for about 20 to 25 minutes and then the run time will get about 4 or 5 minutes shorter and the off time should get about 5 to 10 minutes longer and every time it cycles the run time should get shorter and shorter and the Off times should get longer and longer until it reaches it's minimum run time and it's longest Off time.

 

[luthj]

Watts is not a unit of measurement for energy. Your numbers indicate 224 watt-hours per day. That is roughly a duty cycle of about 14% with a 65W consumption when running. If you measure the power when running for most fridges it will likely be around 40-65W, or about 4-5A at 12.5V.

Your meter is obviously counting watt-hours. If you connect a watt meter, or just measure amps, you can see the running power consumption. Ohms law. V=I*R Watts(power)=V*I

 

[67cj5]

Watts is not a unit of measurement for energy. Your numbers indicate 224 watt-hours per day. That is roughly a duty cycle of about 14% with a 65W consumption when running. If you measure the power when running for most fridges it will likely be around 40-65W, or about 4-5A at 12.5V.

Your meter is obviously counting watt-hours. If you connect a watt meter, or just measure amps, you can see the running power consumption. Ohms law. V=I*R Watts(power)=V*I

It runs a lot less than that and when it is on AC it uses about 0.33amps while running and when it shuts off in sleep mode it is using 4 to 5.4w and about 0.08 to 0.09amps.

 

[OpenTrackRacer]

The setpoint on my fridge and the temperature shown usually are far off. The readout usually shows colder than my wireless thermometer too. I think I had the fridge set at 37-38 degrees when I was getting those 33-35 degree readings. Also, Whynter shows their ratings at 77 degrees ambient and it was more like 65 degrees for my testing.