Mini Refrigerator Inverter Question

[foxontherun]

Good morning all,
I purchased a Magic Chef Mini Fridge this AM and in reading the manual, there are a few statements stating it is not DESIGNED to be used with an inverter or for RV use. My plans were to use it on battery when electricity is not available. I plan to use a dedicated pure sine inverter. Is there any safety reason that I shouldn't use it on inverter? Grant it, I am aware it would probably void the warranty. Any thoughts or considerations would be appreciated.

Thanks,
Harry

https://www.homedepot.com/p/Magic-Chef- ... /305026385

[flboy]

Good morning all,
I purchased a Magic Chef Mini Fridge this AM and in reading the manual, there are a few statements stating it is not DESIGNED to be used with an inverter or for RV use. My plans were to use it on battery when electricity is not available. I plan to use a dedicated pure sine inverter. Is there any safety reason that I shouldn't use it on inverter? Grant it, I am aware it would probably void the warranty. Any thoughts or considerations would be appreciated.

Thanks,
Harry

https://www.homedepot.com/p/Magic-Chef- ... /305026385

It will work just fine on a pure since inverter. I believe they are just covering their bases since most folks don't know the difference and likely would use a cheaper modified sine wave inverter which IS NOT GOOD for the compressor motor. The pure sine wave inverter is as good or better power as in the house and will shutdown if battery gets low without damaging anything.

Use it with a pure sine wave inverter and you are fine. If you have a problem under warranty.... just don't tell them it was used with an inverter then you do not have to explain anything.

I have been using a 4.3 cu. ft. (single door) Magic Chef in my CTC for 3 years now with absolutely no issues. I think I paid ~$129 or so at the time on sale.

[Vspec]

How much of an inverter would be required to run a mini fridge of that size, would a 1000w suffice?

[GuitarPhotog]

Nothing in the specs for that fridge give any idea of electrical power consumption, so it's impossible to tell if a 1000 W inverter will suffice. Inexpensive compressor fridges are notorious for high in-rush startup current requirements. An inverter that "sags" under heavy load may cause the compressor to stall and burn out.

YMMV


<Chas>

[flboy]

Nothing in the specs for that fridge give any idea of electrical power consumption, so it's impossible to tell if a 1000 W inverter will suffice. Inexpensive compressor fridges are notorious for high in-rush startup current requirements. An inverter that "sags" under heavy load may cause the compressor to stall and burn out.

YMMV


<Chas>

That is a good point and good to mention. Rule of thumb for inductive inrush on a compressor motor... 10X the running current just for the fridge startup(some may be slightly higher and "mileage may vary").... then if you have other things you plan to run simultaneously, need to be sure you have it covered.

Having said that, with either appliance (the inverter or fridge), they should have protection built in. In the case of the inverter, if you have other things running and the fridge comes on and exceeds max current due to inrush, the inverter should trip overload and just shut off. Likewise, if the Fridge sees a voltage sag beyond a certain threshold,a relay should drop out to protect the compressor. Most appliances are "smart" in this way due to frequent power sags and etc. on the grid. It is common where I live in heat of summer with the heavy home cooling load across the state.

I'd personally just get a 1500W Pure sine inverter since the standby current will be nearly the same. You will have plenty for the fridge and can then run a few other "heavy" draw devices like a blender, small microwave, or etc. as needs demand without getting into that 80% continuous load keepout area. Just be cognizant of what is on and that the fridge is there and may need to start up.

[foxontherun]

Thanks for all the input and things to consider, I appreciate it. It's great to know that a pure sine will work out. My plan is to have a dedicated pure sine inverted just for the fridge and then a second one to do anything else.

As far as energy consumption is so far (using a P3 P4400 Kill A Watt Electricity Usage Monitor), the past 24 hours stats are .53 KW for 24.23 hours. Refrigerator temp after 3.5 hours was down to 46 degrees, so I adjusted the thermostat from 3.5 to 4 and checked again 5 hours later and fridge temp was 45. At the end of the 24 hour period the freezer temp was 7 degrees. The refrigerator was in a 86 degree garage.

I just put a mini tray of ice, regular tray of ice, and a 40 oz peanut jar filled with water to test ice making ability.

Thanks!
Harry

[featherliteCT1]

foxontherun,

Thanks for posting real data on how your unit is working and power consumption.

[flboy]

Thanks for all the input and things to consider, I appreciate it. It's great to know that a pure sine will work out. My plan is to have a dedicated pure sine inverted just for the fridge and then a second one to do anything else.

As far as energy consumption is so far (using a P3 P4400 Kill A Watt Electricity Usage Monitor), the past 24 hours stats are .53 KW for 24.23 hours. Refrigerator temp after 3.5 hours was down to 46 degrees, so I adjusted the thermostat from 3.5 to 4 and checked again 5 hours later and fridge temp was 45. At the end of the 24 hour period the freezer temp was 7 degrees. The refrigerator was in a 86 degree garage.

I just put a mini tray of ice, regular tray of ice, and a 40 oz peanut jar filled with water to test ice making ability.

Thanks!
Harry

What does it use for power when it is running? Should be <100W I'd think. Probably closer to 60W?

[foxontherun]

Your welcome featherlite. I am also impressed with how quiet it is; wasn't sure it was running but it is, nice and cold.
Harry

[foxontherun]

Don, I am still learning how to use this monitor but I think the answer is 65 - 68. I checked several times and the fridge is finally running again, and the 65-68 was what the monitor showed where before it was zero. I got these numbers from the watts/VA button.
Harry

[flboy]

65 to 68 is about what I'd expect. If you are getting a 1000W pure sine inverter, I'd be suprised if it didn't work. 1000W will have a 2000W surge so you should be able to run the fridge with alot of margin and still run other things .

Sent from my SM-N970U using Tapatalk

[McDave]

You have been given some good info and advice already this morning. I have a small 12vdc/110vac Norcold RV fridge that is really pretty much the same as any other small fridge except the inverter is built in. It draws about 45watts when running. I cant tell you what the start up spike is but a 1000 watt inverter would be plenty to handle the load. I would suspect that Magic Chef would use 50-65 watts max. when running. If that inverter can handle starting a power drill or saw it can handle a fridge.

McDave

[Trebor English]

I have a Haier 1.7 cubic foot and a 400/800 watt Harbor Freight $26 MSW inverter. If I hook it all up and then turn on the inverter the voltage sags and the compressor never starts. At zero RPM and 100 volts that's bad for the fridge. If I turn on the inverter no load then turn on the fridge it starts and runs fine. The model 400/800 inverter doesn't really put out 400 watts. It seems to be ok at 350 watts continuous. The inverter has its own startup surge that must be separated from the fridge surge by a second or two.

It may be that a more expensive 1500 watt pure sine inverter will be better but it wouldn't surprise me if the combined starting of the inverter and fridge was problematic.

[flboy]

A MSW inverter of proper size will run the fridge, but ever notice the different sound it makes? The motor will get the power it needs, but it what it does not get from the RMS voltage, it will get in current which heats windings in motor and reduces lifespan.

Always turn on inverter first and let it settle before applying a load
Why would you do otherwise? Not surprised it doesn't work.

Sent from my SM-N970U using Tapatalk

[featherliteCT1]

flboy,

I bought an Arctic King 1.1 cu ft upright freezer, rather than a refrigerator, because the freezer has more insulation than the refrigerator, but I use the unit as a refrigerator.

I use a digital temperature controller and a relay to cycle a Renogy 700 watt pure sine wave invertor, on and off, in order to regulate the temperature. The controller cycles the invertor on and off to maintain the temperature within the desired set point range.

Based upon preliminary bench testing, after the temperature lowers down to my 39 degree F set point, on average, the freezer uses about .8 amps per hour (at 12v), when ambient temperatures were 70 degrees F. I think that this is significantly less amps compared to a comparably sized Dometic refrigerator.

So far, the setup is working fine, albeit not yet in brutally high ambient temperatures.

Do you think that cycling the invertor on and off will eventually degrade the invertor and/or the refrigerator?

Thanks!