Help with installing a DC fridge

Still trying to figure a few things on this…. I have a 24v sys. Magnum 2024 inverter! Midnight MPPT. Several small cabins run off this (mostly just lights with one small freezer and fridge). all running on110 volt.
I want to install (add) a new unique 24V dc fridge.
Trying to figure out what gauge of wire to use. Need 45feet of run. (Thinking 10 gauge)?
Where do I connect this wire to the system? Thinking to a 15hp breaker in the the inverter junction box (somewhere in there)!
At the fridge…just use marets to connect fridge wiring to the 10g wire (in a box) or?
I know, simple questions but, in the middle of nowhere, limited electrical skills on dc.
Any comment would be appreciated. Thanks.

45 feet of dc is a lot of voltage drop.
Average 300W fridge drain is around 12A so, #10 will work, but the fridge is only going to see about 22V due to voltage drop from such a long circuit.
Make sure you have clean tight connections, and a good breaker or fuse as close to the attery as possible for this.
Odds are high the starting amps on the compressor will hit 50 or so too.

Supervstech said:

45 feet of dc is a lot of voltage drop.
Average 300W fridge drain is around 12A so, #10 will work, but the fridge is only going to see about 22V due to voltage drop from such a long circuit.
Make sure you have clean tight connections, and a good breaker or fuse as close to the attery as possible for this.
Odds are high the starting amps on the compressor will hit 50 or so too.

Click to expand...

Thanks for your feed back. I was wondering about the long run of cable. Here is the spec sheet of this fridge. What do you think?

Average run current amps 2.62 @24 volts
That is probably a Danfoss 50 compressor, those are the state of the art in DC fridges. figure 4x that for start current. They soft start, really a great product.
Your running voltage drop will be minimal with 10GA wire.
Edit: yes it's a Danfoss.

10 is plenty
12 might even be ok.
Your goal is to keep the voltage drop under 3%.

Assuming the compressor runs at a 4 amps or so

Options could be to use a normal AC fridge and an inverter with a stand by mode.
The costs of DC vs conventional fridge with inverter is worth running the numbers on

It's not even close. those Danfoss are really great. they put them in all sorts of DC fridges for boats and RV's.
When they say the average run amps is 2.62@24v, they are not BSing. Nor are they with the 584WH for 24 hours.
Running an AC unit through an inverter will not be close at all to those numbers. They are the bomb for direct off grid usage.

Curious:
Plugged in 14 meters one-way, 3A 26.2vDC into an online DC cable calculator got 12 ga.
Re-ran with likely start up amperage of 12A and got 8 ga.

If It were me, I would use 10ga for the installation.

Yeah, 63W isnt going to stress 10ga.
No issues at all, even the startup amps will be minimal voltage drop.
Should be fine.

OffGridForGood said:

Curious:
Plugged in 14 meters one-way, 3A 26.2vDC into an online DC cable calculator got 12 ga.
Re-ran with likely start up amperage of 12A and got 8 ga.

If It were me, I would use 10ga for the installation.

Click to expand...

When you size you do it for the running amps not the starting.
These are inverter compressors so they don't have a high inrush

Even with 12 at 45 feet and a draw of 12 amps your looking at a momentary drop of around 7% or 8%.
That's really nothing.
In some cases thats to your advantage, it gives you a momentary reduction in starting amps and softens the torque shock to equipment.

Section 28 of the Ontario code has specific rules for hermetically sealed compressor motors, and motors in general.

If you have 10 and its not an additional costs run 10...
But it is not going to make any difference.

Here pretty good calculator I just used.
Also notice it takes into account DC ( lower series inductance of wire )

Back of the Ontario code has tables that let you do a long hand wire calculation but it does not take into account DC

Moosefinder said:

Thanks for your feed back. I was wondering about the long run of cable. Here is the spec sheet of this fridge. What do you think?

Click to expand...

Rona has a similar size AC fridge thats direct cool for as cheapo as 299 I have seen.
A Sepco ( Danfoss made in China )compressor can be had pretty cheap on Ebay....

R600a is not regulated like CFCs and HFCs and can be bought pretty easy..
If you find a fridge guy or you want to tinker thats is something to think about.
You can build a similar solar fridge for about 2/3 the cost even if if you need to pay an HVAC guy to charge it.

Can you find a guy to charge it ask first R600 is pretty new and most guys don't actually fix fridges anymore.
A new fridge is so cheap they are not cost effective to repair.
Explaining you want a compressor and why might motivate an appliance guy ( get the right guy ).

If you find a free fridge that is direct cool, functional and uses R134 the AC guy might be more inclined to use as an older refrigerant that he has more experience with.
This is a comfort thing with these guys....

The HVAC guys are already using the R600.

I would be tempted to play with this.
Its got a very small sweep volume but can be spun up to 6000 rpm.
As an experiment with an old bar fridge I might try it.

ZH2024A 24V Car Refrigeration Air Compressor Fridge Freezer For Micro Compressor on ebay.​

or

12V 24V DC Car Refrigeration Air Compressor Fridge Freezer Marine Solar QDZH35G​

Is larger but still only around 3.5cc and might be small for the 10 CF fridge you want.
The Rona one I think Is 7 Cf and I would think this is close..
Match like for like in compressor sweep...

But they are not appliance guys and most are not open to a compressor swap on a fridge.
In that case explain to them these are simply the same things as an inverter AC unit.
Same rules same methods..

I'm an electrician and even I can do it, but I don't have gauges.
You can eyeball a lot of these if you understand, watch for frost line on the Evaporator line for example tell you you have an over charge/
watch the running current...
Also a Sepco DC compressor has an inverter with adjustable speed so you can tune the system based not only on charge and pressure but speed.

skyking1 said:

Average run current amps 2.62 @24 volts
That is probably a Danfoss 50 compressor, those are the state of the art in DC fridges. figure 4x that for start current. They soft start, really a great product.
Your running voltage drop will be minimal with 10GA wire.
Edit: yes it's a Danfoss.

Click to expand...

Great! Thanks for your help!

Some great info and help guys, thanks!!! Think I will go with the 10G cable (I have it it on hand) feel safe with that now. The unique fridge sounds like a good choice and we are getting a super deal it this from them. Excited to try it.
One last question still outstanding for me….the fridge comes with a short feed cable from the until. I need to connect to my 10g cable. Was going to run both into a box and just market wires together? Acceptable?

Perfectly exceptable to use that wire.
Just be sure to make the connection in a box and use the correct type of starin relief so you do not squash or crush the insulation.

The wire from the appliance probably has cab tyre or some other extension cord like wire from it.
Use a connector that looks like this...



I would also suggest you lable the box as 24 volt DC and its source so no one makes the mistake of connecting something else too it that requires Ac power from your inverter.

Not recommended but there are some peculiar plug ends you can buy for uncommon voltages.
This sad sleeping looking fellow is a 240 volt 15 amp plug.

I've never seen it in a home and it has very limited use for anything else.
You could use this on the fridge and in your connection box to make it easier to move the fridge from time to time or run other 24 volt DC loads.
Clearly make on all receptacles 24VDC...

This would not be a code Compliant thing to do!
But if your off grid it does not matter...

The other option is to use Anderson connectors - as these are more common for DC anyway, and no chance someone plugs in an AC device to one. I have found Anderson connector 'bases online, so they can be mounted into a junction box with a bit of cut and fit.

skyking1 said:

It's not even close. those Danfoss are really great. they put them in all sorts of DC fridges for boats and RV's.
When they say the average run amps is 2.62@24v, they are not BSing. Nor are they with the 584WH for 24 hours.
Running an AC unit through an inverter will not be close at all to those numbers. They are the bomb for direct off grid usage.

Click to expand...

I have a Danfoss in my Dometic CFX95, draw is about 36W on 12V.

The 6-15 was the standard until quality DC connectors became common.
Now, Anderson Power Poles are my go to choice.

DPC said:

Perfectly exceptable to use that wire.
Just be sure to make the connection in a box and use the correct type of starin relief so you do not squash or crush the insulation.

The wire from the appliance probably has cab tyre or some other extension cord like wire from it.
Use a connector that looks like this...

View attachment 215977

I would also suggest you lable the box as 24 volt DC and its source so no one makes the mistake of connecting something else too it that requires Ac power from your inverter.

Not recommended but there are some peculiar plug ends you can buy for uncommon voltages.
This sad sleeping looking fellow is a 240 volt 15 amp plug.
View attachment 215978
I've never seen it in a home and it has very limited use for anything else.
You could use this on the fridge and in your connection box to make it easier to move the fridge from time to time or run other 24 volt DC loads.
Clearly make on all receptacles 24VDC...

This would not be a code Compliant thing to do!
But if your off grid it does not matter...

Click to expand...

Good info DCP. Thanks. I will definately connect in a box with good cable protection/relief as they enter. I was wondering if they is such as thing as a 24 volt receptacle…but think I will just maret the wires.

Moosefinder said:

Good info DCP. Thanks. I will definately connect in a box with good cable protection/relief as they enter. I was wondering if they is such as thing as a 24 volt receptacle…but think I will just maret the wires.

Click to expand...

Probably....
A cigarette lighter socket lol

Are you completely off grid and in a unorganized area?
If so do what ever you like but do it in the spirit of the CEC and try and follow rules that apply to you.
That 240 volt 15 amp plug is perfectly reasonable to use.