Another fridge question

[tinstartrvlr]

Evening all,

Does anyone have any concrete information about how many amps a mid size fridge draws while running, and during startup?

About to replace my unfixable Dometic with a residential fridge (tired of fighting with Dometic), but concerned about amperage as I only have 30 amp system. I know the Dometic used about 3 amps when running on electric, so no big deal, but my research about residential fridges have shown amp usage all over the place. I've had to dig deep to find specs on specific fridges; most only offer how well they "save energy" but don't really give specifics.

I've seen from less than 2 amps to over 12 amps running so not sure what is correct.

Talking about 9-11 cubic foot fridge, not a full size.

Any thoughts please?

[crosscheck]

Almot wrote:

crosscheck wrote:
Interesting to note that the 9 cuft NovaKool fridge has the same outside dimensions as the 6 cuft Norcold absorbtion fridge.

We can easily handle the power for the 9 cuft compressor fridge if the Norcold poops out with 490W solar and 4 6V GC-2 batteries.

The OP is on grid power.

9 cu.ft fridge with a big freezer compartment - about 60-70 AH daily draw - is a lot of burden on 490W solar. In December in Mexico my 490W system barely harvests 30 AH on a dark day with some rain, and such days do happen sometimes. Probably would harvest 90 AH on a good day - which would still be marginal with 9 cu.ft. fridge. OTH, with propane fridge 90 AH is more than I need, batteries are full and floating all afternoon.

People "asking" about compressor fridges, especially fridges over 9 cu.ft, don't usually have solar and are don't plan on having one. They simply want a shore home experience - in a small box of trailer, which is hardly possible to achieve anyway, but this is what they and their family want 🙂

It is normal for compressor fridges (both 12V and 120V) to need less cabinet space than same volume propane fridge. The cost of 12V units with variable speed is about 3 times the cost of 120V units with fixed speed.

I was referencing the post from Copperhead which had to do with a mid sized compressor fridge which is what the OP was asking about.

5.2A(9 cuft) x 12 hr.(50% cycling)= 62.4AH. Maximum solar =26A x 4hr(mid day)= 104AH.(490W)
4.4A(7.5 cuft) x 12 = 52.8AH =18A x 4hr = 72AH (330W). I have not accounted for solar gain in the less than optimal hours of daylight.

Looks like, with our camping style, there shouldn't be any problems feeding a compressor fridge with our present set up if we replaced the current 6 cuft RV fridge with a 9 cuft NovaKool9000 unit.

Appologise to the OP if I got off topic.

Dave

[Almot]

crosscheck wrote:
Interesting to note that the 9 cuft NovaKool fridge has the same outside dimensions as the 6 cuft Norcold absorbtion fridge.

We can easily handle the power for the 9 cuft compressor fridge if the Norcold poops out with 490W solar and 4 6V GC-2 batteries.

The OP is on grid power.

9 cu.ft fridge with a big freezer compartment - about 60-70 AH daily draw - is a lot of burden on 490W solar. In December in Mexico my 490W system barely harvests 30 AH on a dark day with some rain, and such days do happen sometimes. Probably would harvest 90 AH on a good day - which would still be marginal with 9 cu.ft. fridge. OTH, with propane fridge 90 AH is more than I need, batteries are full and floating all afternoon.

People "asking" about compressor fridges, especially fridges over 9 cu.ft, don't usually have solar and are don't plan on having one. They simply want a shore home experience - in a small box of trailer, which is hardly possible to achieve anyway, but this is what they and their family want 🙂

It is normal for compressor fridges (both 12V and 120V) to need less cabinet space than same volume propane fridge. The cost of 12V units with variable speed is about 3 times the cost of 120V units with fixed speed.

[crosscheck]

Copperhead wrote:
Dometic makes some really good 12v / 115v compressor style fridges that are far more efficient than residential units. And they are designed as direct fit replacements for typical RV/TT absorption style fridges. On Dometic's site, they say their 8 CF compressor 12v / 115v fridge uses about 9.6ah on DC and about 1ah on AC. Also states about 70w on AC power. They use variable speed compressors for reduced power consumption.

These units are 12v/24v and 114v/240v. They can be switched to what one is using.

The 8 CF compressor fridge actually has more like 10 CF storage capacity since none of the cooling fin stuff and other internal things of an absorption fridge. They just call it a 8 CF fridge to show that it is a direct replacement for a 8 CF absorption model. They also have 6 CF units.

https://www.dometic.com/en-us/us/products/food-and-beverage/refrigeration/refrigerators/dometic-amer...

Our 7.5 cuft NovaKool 12/120V compressor fridge/freezer that we had for almost 6 years drew 4.4A per amp meter when cycling. 4 6V AGM's and 330W solar kept us from using the genny and we dry camped 98% of the time. Great little unit. Sold the TC and now have a TT with a 6 cuft Norcold which is working fine. Interesting to note that the 9 cuft NovaKool fridge has the same outside dimensions as the 6 cuft Norcold absorbtion fridge.

We can easily handle the power for the 9 cuft compressor fridge if the Norcold poops out with 490W solar and 4 6V GC-2 batteries. We have tested this type of fridge in the real world of long term boondock camping and as long as you are set up proprly from the start, it is a great way to go.

Dave

[Bill_Satellite]

I still prefer my 20CF HH fridge over anything designed for an RV. Side by side with filtered ice/water through the door. Very nice!

[Copperhead]

Dometic makes some really good 12v / 115v compressor style fridges that are far more efficient than residential units. And they are designed as direct fit replacements for typical RV/TT absorption style fridges. On Dometic's site, they say their 8 CF compressor 12v / 115v fridge uses about 9.6ah on DC and about 1ah on AC. Also states about 70w on AC power. They use variable speed compressors for reduced power consumption.

These units are 12v/24v and 114v/240v. They can be switched to what one is using.

The 8 CF compressor fridge actually has more like 10 CF storage capacity since none of the cooling fin stuff and other internal things of an absorption fridge. They just call it a 8 CF fridge to show that it is a direct replacement for a 8 CF absorption model. They also have 6 CF units.

https://www.dometic.com/en-us/us/products/food-and-beverage/refrigeration/refrigerators/dometic-amer...

[Slownsy]

We have installed a Mitsubishi 340L inverter fridge freezer in our Titanium, it is a 240V it runs via a 375w inverter of our 4/6V batteries 520A. We have 600W solar. Ouer consumption over night is for total fridge, television,lights, water pump everything 14-16% = 83A. FW sitting in partial shade for several hours a day full sun 5-6hours solar recharge batteries and run fridge etc during day.
Be aware we are in Australia with 240V.
Frank.

[theoldwizard1]

tinstartrvlr wrote:
... but my research about residential fridges have shown amp usage all over the place. I've had to dig deep to find specs on specific fridges; ...

Exactly what I would suspect !

If your shore power connection is 30A I can not imagine you having any problems with the exception of the refrigerator and the air conditioing STARTING at exactly the same time. If one is running and the other one starts I am sure you will be fine.

If you do plan to ocassionally boondock, at a minimum I would have two 6V golf cart batteries and at least a 2000 watt pure sine wave inverter. Remember a residential refrigerator is a pretty good "ice chest" so if you charge the batteries with a generator up to near 100% before "quiet time" at night and keep the doors shut, even if the inverter shuts down from low voltage over night, everything will be fine until the next morning.

[Almot]

I think the OP was worried more about start surge, rather than running current.

Modern efficient fridges can still jump high on start-up, except for inverter fridges that have variable speed compressors. I was unable to find any numbers for those, other than general statements that they either don't surge or surge very little.

[Dutch_12078]

CA Traveler wrote:

Dutch’s Haier HA10TG31SB refer above is rated at 330kWh and the 2A and 6A label may suggest a worst case scenario.

Basically with a A/C, TV, lights and refer you should be OK on 30A as a typical 10 cu ft refer AC draw is 1-2A possibly with a higher startup surge.

Exactly... According to my amp meter, my fridge typically runs close to 1.2 amps, and 1.5 when the defrost fan kicks on for a few minutes. The peak LRA (startup) current only hit a 5.1 amp peak over several tests. Another factor with a residential fridge versus an RV absorption fridge running on electric is that the residential fridge will typically have much shorter cycle on times, with longer cycle off times than the RV fridge, making overall power consumption less. We've never been concerned when we're on a 30 amp only site. We just remember to only run one A/C at a time, no hair dryer and microwave at the same, and that sort of common sense notions like that. The fridge takes care of itself and has not been a concern. It also works nicely on a dedicated 600 watt/1200 watt surge PSW inverter when we're underway without the generator running.

[time2roll]

tinstartrvlr wrote:
concerned about amperage as I only have 30 amp system.

Doubt this will be an issue vs the 3 amps an absorption fridge draws when running on electric. If it gets to be an issue for the start surge you could always run it full time off the inverter and let the battery absorb the start surge.

[CA_Traveler]

Modern refers are very efficient and often give a yearly power usage. As an example use 364kWh. For 1 day 364kWh/364 = 1000Wh for 1 day.

Per hour it's 1000Wh/24h = 42W. Assuming it cycles on 50% of the time it then draws 42/.50 = 84W while running.

For 120V AC operation that's 84/120 = 0.7A when running.

Using a multiplier of 11 for battery/inverter usage that's 0.7A*11 = 7.7A DC when running.

Also for battery/inverter usage it would use (for 1 day) 1000W/12.0V = 83AH from the batteries. For 2x GC2 batteries at 230AH that’s 83/230 = 36% discharge for just the batteries.

Actual power usage will vary depending upon usage and ambient temperatures

Also some modern refers use variable speed motors and have very little additional start up amp surge.

Dutch’s Haier HA10TG31SB refer above is rated at 330kWh and the 2A and 6A label may suggest a worst case scenario.

Basically with a A/C, TV, lights and refer you should be OK on 30A as a typical 10 cu ft refer AC draw is 1-2A possibly with a higher startup surge.

[dmck413]

Mine runs on a 1000 watt PSW with no problems

[Almot]

Btw, there is a new breed: inverter refrigerators 11 cu.ft LG. It adjusts the compressor speed instead of cycling more (or less).

I think their start-up current should not be THAT high. Does anybody have any measurements?

[tinstartrvlr]

Thanks all,

Dutch, thanks, that is the label I will look for on whatever fridge I buy. Just couldn't find that on any website specs.

I only plan to run the fridge on shore power. For boondocking, a really good cooler will work fine since I don't have solar or a generator.