JC refrigeration AC or DC upgrade?

[woodtrucker]

Just wondering if any of you could tell me whether I should buy the AC or DC conversion for my dometic rm2652.

We are on shore power almost always except for traveling. Would the truck charge battery enough to keep the 12VDC unit cooling while on the road?
If so, I'll go the 12V route.
Thanks,
Scott

[scottykrug]

We installed the dc version and love it. Ironically we also had to install a small inverter during the process. The newer Dometic fridge we replaced required a small input of AC voltage to trick it into running.

[n0arp]

billyboy wrote:
Why I asked about a modified inverter is that I already have one. I want to know if it will run ok on it.

Directly from the product page:

Converts your existing fridge to a residential fridge (which eliminates your LP gas). This cooling unit is built with a compressor system and not only do you get to keep your same fridge and controls you are used to, but there is no need to remove the windshield or window to get the old fridge out and the new in – nor the hassle of cutting or redoing the cabinets to make a new fridge fit. Also there is no need to have the coach perfectly level for the fridge. It pulls less than 1 Amp and will run off a 600W inverter (does not require pure sine wave). This unit is coated with a corrosion/rust preventive paint, and is very user-friendly to work on in the field should it ever need repair in the future. It is designed to withstand hot/humid temps and will keep your ice-cream hard. Comes with a 3-year warranty. See our easy DIY install video or have it factory installed.

For questions like this, why not just reach out to them (or look at their site)?

[pianotuna]

billyboy,

It might. Replacing a compressor fridge would be expensive.

If it is an absorption fridge, then msw is fine.

[billyboy]

Why I asked about a modified inverter is that I already have one. I want to know if it will run ok on it.

[rdhetrick]

jshupe wrote:

rdhetrick wrote:
I think that's true if the inverter only has the losses when the compressor is running, but there is a dead load to the inverter even when it's doing nothing. I admit I haven't ran the numbers, but I've got to believe that unless you're turning the inverter off when the refer doesn't need it and on when it does, it's got to use more power over the course of a day.

Of course, but we haven't turned off our inverters except for firmware updates. Our systems (and I guess I should be abundantly clear that this is in no way unique to us) are designed around 24/7 operation in both rigs. If you don't have such a system, then DC makes more sense.

Gotcha. I don't have solar on my coach so when I'm boondocking, I turn the inverter off unless I need it.

[n0arp]

rdhetrick wrote:
I think that's true if the inverter only has the losses when the compressor is running, but there is a dead load to the inverter even when it's doing nothing. I admit I haven't ran the numbers, but I've got to believe that unless you're turning the inverter off when the refer doesn't need it and on when it does, it's got to use more power over the course of a day.

Of course, but we haven't turned off our inverters except for firmware updates. Our systems (and I guess I should be abundantly clear that this is in no way unique to us) are designed around 24/7 operation in both rigs. If you don't have such a system, then DC makes more sense.

Most of the full-timers we know with moderate to large investments in solar have their inverters on 24/7 and never turn them off except to perform maintenance.

[rdhetrick]

jshupe wrote:
I'm late to the thread, as it looks like you've already made your purchase.

I have the 120V version in my truck camper, which uses 1.0-1.3kWh per day. I chose it because I have a native 48V bank, so it's being converted one way or the other, and I wanted the slightly extra cooling capacity.

The following is directly from their FAQ:

Q. what is the duty cycle (run time) A in our testing @ 80F the AC compressor will run approx. 56% and the DC approx. 64%, that is not opening and closing the doors. So, this will vary some according to your usage
Q. which is most the power efficient 120V or 12V A. on paper the 12V is the most efficient @ 7.5A 90W, but it runs some slower than the 120V, so in the end they are practically the same. But if no inverter is on board then the 12V is still much faster than your gas/elect.

Our compressor pulls 90W on the AC side (not 96W). At the 56% duty cycle mentioned above, that works out to 1.209kWh/day, which is in line with what we've observed.

The DC compressor is advertised to pull 90W. At the mentioned 64% duty cycle, that's 1.382kWh/day.

By those numbers, the AC version is 13% more efficient. Inverter losses are usually a little under 10%. That indicates the AC version may actually be more efficient overall, even accounting for the inverter, but just like their FAQ says, it's more or less a wash.

I think that's true if the inverter only has the losses when the compressor is running, but there is a dead load to the inverter even when it's doing nothing. I admit I haven't ran the numbers, but I've got to believe that unless you're turning the inverter off when the refer doesn't need it and on when it does, it's got to use more power over the course of a day.

[n0arp]

I'm late to the thread, as it looks like you've already made your purchase.

I have the 120V version in my truck camper, which uses 1.0-1.3kWh per day. I chose it because I have a native 48V bank, so it's being converted one way or the other, and I wanted the slightly extra cooling capacity.

The following is directly from their FAQ:

Q. what is the duty cycle (run time) A in our testing @ 80F the AC compressor will run approx. 56% and the DC approx. 64%, that is not opening and closing the doors. So, this will vary some according to your usage
Q. which is most the power efficient 120V or 12V A. on paper the 12V is the most efficient @ 7.5A 90W, but it runs some slower than the 120V, so in the end they are practically the same. But if no inverter is on board then the 12V is still much faster than your gas/elect.

Our compressor pulls 90W on the AC side (not 96W). At the 56% duty cycle mentioned above, that works out to 1.209kWh/day, which is in line with what we've observed.

The DC compressor is advertised to pull 90W. At the mentioned 64% duty cycle, that's 1.382kWh/day.

By those numbers, the AC version is 13% more efficient. Inverter losses are usually a little under 10%. That indicates the AC version may actually be more efficient overall, even accounting for the inverter, but just like their FAQ says, it's more or less a wash.

[wborst]

theoldwizard1 wrote:

billyboy wrote:
Will a cheap harber freight modified sine wave 1700 watt inverter run the fridge

$35 difference between the HF Jupiter 1500 watt modified sine wave inverter and the HF Jupiter 2000 watt pure sine wave inverter.

A residential refrigerator runs better on pure sine wave.

The Jupiter 2000 watt inverter from HF is a modified sine wave inverter. Just checked their web site.

[pianotuna]

Billyboy how long do you want the fridge to last? PSW is better.

[theoldwizard1]

billyboy wrote:
Will a cheap harber freight modified sine wave 1700 watt inverter run the fridge

$35 difference between the HF Jupiter 1500 watt modified sine wave inverter and the HF Jupiter 2000 watt pure sine wave inverter.

A residential refrigerator runs better on pure sine wave.

[goducks10]

When I was looking to replace my POS Norcold I checked out JC fridges. It was $695 and $280 for shipping to the west coast. $975 total.
I then looked at 12V specific RV fridges. I found a 12V RV/Off grid GE 9.8 cu.ft that was a direct replacement for my Norcold N8X. (Reall 7.5 cu.ft)
IIRC $899 at the local appliance store. Added a 3 yr warranty for $50. Total $949.

Even though I already have a 2000W inverter I didn't want to have to run the inverter 24/7 when dry camping. Having a 12V only allows me to run directly off my four 6V GC batteries. When on shore power the batteries are getting charged.
I also have 400W of solar. I also gained 2.3 cu.ft.

Only got to use it at the end of last season. So far we love it. Way more room inside. It cools down super quick. Freezer gets almost too cold but the temps stay more constant than with the Norcold. It's also quiet. We can hear the compressor run when we're laying in bed but nowhere else. I thinks it's more of a vibration as I pushed on a wood panel in the bedroom closet and the noise quit. Other than that we never hear it during the day.

[woodtrucker]

Just ordered 12v cooling unit from jc refrigeration! Thanks for the great info all!

[billyboy]

Will a cheap harber freight modified sine wave 1700 watt inverter run the fridge