Advanced DC compressor ideas

Shadow44

So I am a technician that replaces compressors almost daily. I am just about to embark on a journey to take a standard refrigerator and replace the compressor with a direct current one. I believe the evaporator fan will be the biggest challenge. Has anyone tried this? The biggest advantage would be bypassing the the loss in the inverter, but my thoughts are eliminating the fail point from the inverter, and running directly from the batteries.

dennis461

In USA, most compressors in refrigerators are a combination unit.
Are you thinking o this type of unit?

BB.

Danfoss makes a number of DC refrigeration compressors:

http://refrigerationandairconditioning.danfoss.us/products/compressors-for-refrigeration/dc-compressors-for-mobile-cooling/

I don't know enough about picking the right one and how it would affect the condenser sizing.

These types of Danfoss compressors (as far as I know of the basics) is a small DC to 3 phase inverter--designed to work with batteries or solar panels.

You could do similar with a standard AC inverter and an energy star refrigerator... Compare the costs and overall system design between the various options.

For a small system--A DC fridge (directly from solar panels or with DC battery bank + solar + charge controller + etc.) can make economic sense.

If your off grid solar system is going to supply other loads (say ~3.3 kWH per day for LED lighting, well pump, washing machine, laptop/LED TV)--Then you might want to get a ~1,500-2,000 Watt AC inverter and a ~650 AH @ 24 volt battery bank with ~2,400 Watt solar array (very rough numbers--Lots of details and questions to address).

-Bill

Estragon

I use a danfoss DC compressor in a heavily insulated box freezer. The evaporator can be either a flat plate or small box (for use as a freezer compartment in a fridge). I guess you could rig up a 12v muffin fan over a plate, but it isn't really needed. These units are very efficient at keeping stuff cold, but are slow to get stuff cold.