120V AC Fridge Energy Usage

[featherliteCT1]

Last week, my Walmart sourced Arctic King 1.1 cu ft Upright Freezer, 120v, with an add on temperature controller to cycle my 700 watt inverter, to cycle the unit on and off, in order to maintain 39 deg F., in 80 degree ambient temperature, averaged .75 AH, over a 24 hour period. I am very pleased with the energy use and performance.

[bdosborn]

Very interesting, was the meter on the line side (12V) or load side (120V) of your inverter? Either way, that's a value that's right in the expected range for a DC fridge. Thanks a bunch for posting this, I'm defiantly going with a 120V fridge now.
Bruce

[bdosborn]

Have a look at the Norcold Polar line. Their documentation says the 12v 8cu/ft fridge pulls .93A.

That's a 3 way fridge,I'd look at that one if I was going that way. The next fridge goes in a van and I wouldn't be able to force myself to cut the required vents in the side of the van. Also, those fridges have pretty strict leveling requirements that will be tougher to get to in a van.

Bruce

[OP827]

Last week, my Walmart sourced Arctic King 1.1 cu ft Upright Freezer, 120v, with an add on temperature controller to cycle my 700 watt inverter, to cycle the unit on and off, in order to maintain 39 deg F., in 80 degree ambient temperature, averaged .75 AH, over a 24 hour period. I am very pleased with the energy use and performance.

This is great result, thanks for sharing. Is your inverter a pure sine or a modified sine? Can you share links to inverter and fridge (is it this one?) to see full specs?

[featherliteCT1]

Yes, that is the link to the Arctic Freezer I bought from Walmart. Here is the link to the Renogy 700 watt pure sine inverter I bought in April 2020, for $130; now it is only $117.

https://www.walmart.com/ip/Renogy-700W- ... lsrc=aw.ds

[OP827]

Yes, that is the link to the Arctic Freezer I bought from Walmart. Here is the link to the Renogy 700 watt pure sine inverter I bought in April 2020, for $130; now it is only $117.

https://www.walmart.com/ip/Renogy-700W- ... lsrc=aw.ds

Thanks!

[bdosborn]

Interesting video on AC fridge energy usage...



Bruce

[featherliteCT1]

Thanks for posting the informative video.

In his setup, he is feeding power to the Inkbird temperature controller directly from the battery, which means that the voltage feeding into the Inkbird will be fluctuating up and down as the battery voltage fluctuates, say from 14.2 volts during charging down to say 12.2 volts when the battery is 50% discharged. I have no idea if that will adversely affect the Inkbird over time.

To eliminate fluctuating voltage, I installed a cheap adjustable buck converter between the battery and the Inkbird set to feed a constant 12.7 volts into the Inkbird. Now I am wondering if the buck converter was necessary.

On the diy solar forum, some of the posters commented that it is hard on the inverter to turn the inverter on and off while the inverter is under load. I do know that the instructions for both my Honda 2200i inverter generator and my Renogy inverter say not to turn the unit on or off under load. I guess time will tell if my Renogy invertor holds up over time.

[bdosborn]

I'm planning on using a Victron multiplus 2000 inverter that has a search mode to conserve power. It reduces the no-load power usage to 3W.

If search mode is ‘on’, the power consumption in no-load operation is decreased by approx. 70%. In this mode the Compact, when operating in inverter mode, is switched off in case of no load or very low load, and switches on every two seconds for a short period. If the output current exceeds a set level, the inverter will continue to operate. If not, the inverter will shut down again.

That way I don't have to mess with turning the inverter on and off, I just have to throw a bucket of money at the problem.
Bruce

[featherliteCT1]

yes, that Victron unit is a bit salty!

Rather than turning the inverter on and off, an alternative is to plug one of these $35 Inkbird units into the inverter AC outlet plug and then plug the fridge or freezer into the Inkbird unit, which then cycles the fridge or freezer on and off.

Inkbird ITC-308 Temperature Controller
https://www.amazon.com/Inkbird-Max-1200 ... 4620&psc=1

I think I will order one now.

[bdosborn]

I just bought one of the Inkbird thermostats to play with and it's only rated for DC loads. The whole idea of turning the inverter on and off is to cut down on the inverter no-load losses when the fridge isn't running. I don't think turning the fridge off with an external thermostat will save you anything. I would look at adding a relay to the onboard fridge thermostat to turn the inverter off. That way you wouldn't be cycling the inverter while it's under load. You'd need some sort of circuit for compressor delay so the relay didn't open immediately when the fridge thermostat opened.

12v relay.

You'd need to know more about what voltage the fridge thermostat is, if it's 120V you'd need another relay to trigger the the time delay relay.

Bruce

[featherliteCT1]

Thanks Bruce,

I am basically a hack when it comes to electronics but I learn from others like you as I go.

To clarify, I currently have a 120v freezer, a small 1.1 cu ft unit, because the insulation is much thicker than that of a refrigerator. So I use the DC Inkbird first linked below, with a relay, to turn the inverter on and off to control the temperature. In 80 degree temperatures, I use about .7 amps per hour.

https://www.amazon.com/Inkbird-All-Purp ... 8428&psc=1

I just ordered the AC Inkbird next linked below to replace my current DC Inkbird, although with this new Inkbird the inverter will never shut off. I want to compare its current draw compared to my current set up. I suspect that I will use an additional .5 amps with this set up because my inverter on no load standby uses about .5 amps. My thought is that this set up will not damage my inverter by cycling under load.

https://www.amazon.com/Inkbird-Itc-308- ... B01MDSWXY4

Both of these Inkbirds have the ability to program compressor delay. Right now I am using 3 minutes of delay.

Do you think I should use a longer delay?

Thanks for posting the link to that relay. I need to think about how to add that relay to the onboard freezer thermostat to turn the inverter off when the freezer is not under load.

I may need to pick your brain some more as I try to figure things out.

Again, thank you!

[bdosborn]

No problem, let me know how I can help.
Bruce