Norcold 12 v fridge

[Starwatcher]

Hello all.
I have a used Norcold dc-440 12 volts fridge who draws 3.5 amps.
How long it will run with a deep cycle battery of 103 ah, and with 2 battery of 103 ah.

I want to figure if a 3 way cooler (gas and electric) will be more practical
in a 4 X 8 teardrop. (cooler need 1lb of gas per 24 hours and is silent)

I used the formula back to the technical college but now i can't find it anywhere.

Best regards.

[eamarquardt]

A general rule of thumb is that you can get half of the amp hour capacity out of your battery before it's time to recharge. So if you have a 100 amp hour battery you can get 50 amp hours out of it. If you draw 3.5 amps you'll be able to get 50/3.5=14 hours out of it. Not too good. Then you have to put the energy back (charge the battery) and I think the general rule of thumb is the charge current should be no more than 10% of the battery capacity (I may be mistaken) so it will take 5 hours at 10 amps to properly recharge the battery. Where are you planning on getting it?

A gas powered reefer makes a lot more sense as it will run for much longer on a "charge" of propane. I bought one (also a Norcold) just for that reason. Also the literature that mine came with states that the DC mode is just for maintaining the "status quo" and only the A/C and Gas modes have the power to "pull the temp down".

So, running a reefer on DC off of batteries is really not the most pratical way to go. But, you can do anything if you set your mind to it.

Cheers,

Gus

[mikeschn]

Got a link to your gas powered reefer?

Mike...

[AZSpyder]

I have recently looking at that myself. I just picked up a DC-451 on Ebay, due to deliver tomorrow.

The best I have been able to tell is your results will vary. The total consumption will depend on ambient temperature and how often you open the door trying to figure out it the light really turns off.

The 3.5 amps is when the compressor is running. I don't have any personal experience yet but I have seen talk that refrigerators average running 15 to 20 minutes in an hours time if they aren't opened. Assuming to 15 to 20 is close to correct that would put the consumption at 0.875 to 1.65 amps per hour.

Also not being a battery expert I understand they shouldn't be run down more the 1/2 way before recharging. So I figure you should be able to pull 52.5 amps out of a new full capacity 105 amp hour battery. So with the 15 to 20 minute running time an hour it should be able to run about 32 to 46 hours. Twice that with two batteries. This is all assuming the info on running time I found on the net is correct, the battery is at 100% capable and nothing like lights are adding to the battery discharge.

I already have figured out that I am going to need a 60 watt solar panel if I go more then two nights at a camp site without hookups.

I hope this helps, or is even close to correct. I'm interested if someone with experience running the compressor refrigerators can fault my numbers.

As far as gas or DC, if you have the propane that way will last much longer. The gas ones don't use a compressor. When on AC or DC it is done with a heat element. The average DC draw is much higher then a compressor type but that is normally only used during towing so it would pull from the tow vehicle and not an on board battery. At my wife's request I removed the gas from my rig during the rebuild so a DC compressor refrigerator is my only choice.

Jerry

[eamarquardt]

Here is a link to the company that makes Norcold Reefers:

http://www.thetford.com/

Dometic is also a big name in the field:

http://www.dometic.com/enie/


The three way refeers use the absorption process to make cold not the typical compressor, condenser, and evaporator process. Absorption uses heat to make cold not mechanical energy. I'm not sure but I don't think you can get a compressor to run on just 3.5 amps 12 VDC so it's probably an absorption unit and not very "powerful" at that. They do need good ventilation to work effectively.

Hope this helps.

Cheers,

Gus

[AZSpyder]

The DC-440 asked about is definitely a motor/compressor refrigerator and Norcold advertises a 3.5 amp draw on 12 volt. My DE-451 is also compressor and Norcold says it is 3.1 amps. I'v seen the small units advertised as low as 2.7 amps.

A small absorption cooling Norcold, the 323T calls for 11.7 amps on DC. The absorption type are a big difference over the compressor but their main intent is gas powered. Some people I work with say they get up to two weeks on a common size bottle but require outside venting and for some reason they are not supposed to be used on gas while towing (flame blowing out?). 11.7 not not too bad to pull from a tow vehicle then switch to gas at the camp site.

Jerry

[Starwatcher]

Got a link to your gas powered reefer?

Mike...

http://www.mobicool.com/pages/products/ ... s_full.htm

But not shure about the performance of this thing.
Available at my local Canadian tire for 300$.

I found a interesting discussion on that thread.
http://www.expeditionportal.com/forum/s ... hp?t=27799

Chescold and Waeco seems very interesting products but expensive and not available in North America.

Regards.

[eamarquardt]

I hope this helps, or is even close to correct. I'm interested if someone with experience running the compressor refrigerators can fault my numbers.
Jerry

I think you're in the ballpark. 24 hours X 1.65 amps (I’m pessimist) = 39.6 amp hours a day. Close enough to say it requires pretty much a 100 amp hour battery of its own and the battery will be used to nearly its capacity each day (up and down). This is a strain on a battery and will reduce its life.

You could argue that solar panels with enough capacity to charge the batteries and cover the 1.65 amp draw might reduce the cycle load on the battery and extend its life.

So, I think you’re gonna need more battery capacity (weight) and a substantial charging set up to make it work but I could be wrong.

Guess someone will have to try and see what really works. Sounds as though a couple of you have these units on hand so maybe you could do some testing as see what happens.

No fair testing when there is snow on the ground!

You never know till you ask or try!

Cheers,

Gus

[Starwatcher]

One of my co-worker just put a similar Norcold fridge in his GMC safari condo and he didn't had the chance to try it in normal condition.
It had factory installed Thermo-electric unit previously and 2 deep cycle battery and they last 2 days. Everything is better than thermo-electric.

[GregB]

I have an ARB fridge/freezer which is based off of the Engel design. Over 66 hours, with an internal temp of 36 degrees and external temps of 78-87 degrees, it averages .87 amps/hour. Other than eutectic type freezers, this is about as efficient as a 12V gets.

Greg

[Rock]

I believe the fridge the original poster asked about is actually a 45 quart Engel, which is what I have. Here's a link that can be helpful when trying to estimate electrical usage versus inside versus outside temps:

http://www.bigfrogmountain.com/images/MT45F%20curve.jpg

Based on experience it seems to me that the #s people posted above are pretty much right on. Using the fridge in "normal" camping conditions for me (assume an average of 70F ambient over a 24 hour period) and a "refrigerator" temperature inside (say 35F) a good size battery will last about 2 days with normal use. Higher ambient temps, freezer inside temps and opening more often will greatly reduce this.

They are as efficient as electric fridges get, but still power hogs. I figure I'll need a combination of solar and windmill to boondock with it for more than 2 days - which I rarely do. Especially if I feed warm beer into is as cold beer is consumed.

Eric

[Cliffmeister2000]

Got a link to your gas powered reefer?

Mike...

Mike, here's a new 4.5 CF Norcold AC/Gas one on eBay for $500

http://tinyurl.com/yc7kkc9

[Starwatcher]

If i have one 100ah battery and recharge it while driving and use a charger during the night maybe i will be ok.

If i don't have access to 110v, i will simply turn off the fridge and put ice pack instead of the ice cream.

Anyway my teardrop project is still at the frame stage and things can change.

Regards.

[AZSpyder]

I just got a chance to try out my Ebay special Norcold DE-451 and got a bit of a surprise.

This one is a 1.9 cubic foot AC/DC advertised as 3.1 amps on DC. I didn't have a big enough power supply so I hooked it up to my truck battery without the truck running. The refrigerator hadn't been run so it had to run about 6 minutes before cycling off.

I didn't detect a startup surge current but that can be had to see on a digital meter. I did see it pulling 3.9 amps and over the next minute working its way down to 3.7 amps. It spent about a minute at 3.7 before working its way up to 4.5 amps over the next four minuets.

The other night I ran it for a couple of hours on AC at a 70 degree room temperature. After it cooled of it averaged running 21 minuets in a hours time. The run time was in 2 to 2 1/4 minutes time periods. Considering a 2 minute run and the current reading I was getting I think for load calculations my refrigerator will be 4 amps when running. I also found it pulling 72ma when not running so that also needs to be added in. I does pull zero off the battery when 115 VAC is available, running or not. So for this one it looks like 1.5 amps an hour depending on the ambient temperature variable.

Jerry

[eamarquardt]

I just got a chance to try out my Ebay special Norcold DE-451 and got a bit of a surprise.

So for this one it looks like 1.5 amps an hour depending on the ambient temperature variable.

Jerry

Good work. A couple of thoughts:

I don't think the average temp during the summer in many places is 70F. Even here in So. Cal. near the coast the lows are only 65F and the days go from 80F to over 100F. I don't think other places (unless you're up in the mountains) cool off so much as here at night and the daytime temps are similar. I think your estimate is probably low but is nearly identical to my calculations earlier in the string. Somewhere around 40-50 amp/hours/day.

This type of consumption will require a 100 amp/hour battery and means to charge it with 50 amp/hours a day (max maybe 10 amps for 5 hours minimum).

So an important factor in the equation should be how you gonna charge it each and every day keeping in mind the factors that affect the life of the battery (how often is is discharged, how deep the discharge, and how fast it is recharged).

Cheers,

Gus