High altitude problem???

[booster]

Originally Posted by Bud

Keep in mind:

'THE or the ONLY reason an absorption refer exists is that there is not enough reliable electrical power.' Want to use batteries, a compressor refer. How much battery power is required varies by application.

Bud

Yep, adding more battery power so you can run an absorption frig would be pretty silly, IMO. A compressor frig would use maybe 1/4 of the power of the absorption on batteries and it would actually stay cold all the time.

[GallenH]

That's something that's unclear to me. My situation: I have one house battery that gives me 100AH. What would I need to be able to comfortably run a compressor fridge that's say 3-4cf (the size of my small Dometic)? What would that system look like?

1. Would a need a higher output alternator?
2. An inverter?
3. Solar (I have 100W Renogy suitcase)?
4. What size (AH) battery storage? Lithium necessary? Preferred?

Assumption: I'm never in one place longer than 3 days w/o hookup without driving.

I'm guessing that some of you have gone through this process and asked the same questions or figured this out on your own. Any comments would be GREATLY appreciated.........

[booster]

Originally Posted by GallenH

That's something that's unclear to me. My situation: I have one house battery that gives me 100AH. What would I need to be able to comfortably run a compressor fridge that's say 3-4cf (the size of my small Dometic)? What would that system look like?

1. Would a need a higher output alternator?
2. An inverter?
3. Solar (I have 100W Renogy suitcase)?
4. What size (AH) battery storage? Lithium necessary? Preferred?

Assumption: I'm never in one place longer than 3 days w/o hookup without driving.

I'm guessing that some of you have gone through this process and asked the same questions or figured this out on your own. Any comments would be GREATLY appreciated.........

It does vary a lot with conditions, but in general this is what we have seen.


Our 3.1CF frig uses between 17 and 40 amp hours per day, so if you needed 3 days you would use 120ah above what you do now in the worst cases.


100 watts of solar will give you about 30ah maximum under very good sun conditions, so it would nearly keep up in many conditions. But you might also only get 5ah a day if it is rainy or very shady, so tough.


Driving in most class b setups will charge the batteries at somewhere between 50-80 amps, although some older ones may be less. That high rate would only apply until the batteries get to about 70% and then they start to taper how much they will take and it will take a long time to finish charge to full.


If there is not much other battery use, having the semi-norm of 220ah of batteries and 100-200 watts of solar would likely cover almost all of the conditions as you describe them, although multiple bad weather days, batteries that don't get fully charged before starting a no electricity stay, etc could put you outside the range. The fallback position would be if you get really bad conditions and wind up low on power, an hour drive would get you a days worth of charge back.


You would certainly need a battery monitor to keep track of where you are on battery charge, but that is a good idea anyway.

[GallenH]

Thanks for the extremely helpful answer, booster. So does your system not make use of an inverter? Where my fridge currently sits it has 12v leads necessary to run the 12v heating element (mine is so old it doesn't have a board running an auto light, etc.). Unfortunately, PleasureWay insists there's no build manual available for consumer consumption (hard to believe on a RV like mine that's 20yrs old). Also are you running AGMs or Lithium? I assume the former since I've read that one of the advantages to Lithium was it's ability to charge faster. And, last, did you upgrade your alternator?

Again, thanks for the very helpful info. It IS much appreciated.

Glenn

[Roadtrek Adventuous RS1]

Originally Posted by booster

It does vary a lot with conditions, but in general this is what we have seen.


Our 3.1CF frig uses between 17 and 40 amp hours per day, so if you needed 3 days you would use 120ah above what you do now in the worst cases.


100 watts of solar will give you about 30ah maximum under very good sun conditions, so it would nearly keep up in many conditions. But you might also only get 5ah a day if it is rainy or very shady, so tough.


Driving in most class b setups will charge the batteries at somewhere between 50-80 amps, although some older ones may be less. That high rate would only apply until the batteries get to about 70% and then they start to taper how much they will take and it will take a long time to finish charge to full.


If there is not much other battery use, having the semi-norm of 220ah of batteries and 100-200 watts of solar would likely cover almost all of the conditions as you describe them, although multiple bad weather days, batteries that don't get fully charged before starting a no electricity stay, etc could put you outside the range. The fallback position would be if you get really bad conditions and wind up low on power, an hour drive would get you a days worth of charge back.


You would certainly need a battery monitor to keep track of where you are on battery charge, but that is a good idea anyway.

My setup is the 160 watt panel and two AGM 6 volt batteries...in series..

I'm also running a 3.1 Dometic propane refrigerator...

Can any of you tell me if you think I have enough power to run the fridge and for how long?
Seems to be a lot of different answers here.. maybe I didn't provide you with enough details earlier on what size refrigerator I had.. sorry.

[Bud]

Originally Posted by Roadtrek Adventuous RS1

My setup is the 160 watt panel and two AGM 6 volt batteries...in series..

I'm also running a 3.1 Dometic propane refrigerator...

Can any of you tell me if you think I have enough power to run the fridge and for how long?
Seems to be a lot of different answers here.. maybe I didn't provide you with enough details earlier on what size refrigerator I had.. sorry.

Did you miss booster's post? Your answers are there.

Bud

[booster]

Originally Posted by Roadtrek Adventuous RS1

My setup is the 160 watt panel and two AGM 6 volt batteries...in series..

I'm also running a 3.1 Dometic propane refrigerator...

Can any of you tell me if you think I have enough power to run the fridge and for how long?
Seems to be a lot of different answers here.. maybe I didn't provide you with enough details earlier on what size refrigerator I had.. sorry.

15 amps is what I have heard in the past for the absorption frigs on DC, so 15ah per hour of use. Two 6v batteries are usually in the 200ah range of capacity, or 160an usable. 10 hours of use would kill them totally dead assuming they were 100% full to start, which is very iffy with Roadtrek charging systems.


The solar would give a maximum, under good conditions of about 45ah per day, and only during the day would be putting out something like 8 amps during peak hours with great sun.


Realistically, you would be likely limited to 3-5 hours per day and then only for a day or two unless you ran the van engine a lot.



Also remember that absorption frigs don't cool well on DC, so it might not be any better than the propane at altitude.

[booster]

Originally Posted by GallenH

Thanks for the extremely helpful answer, booster. So does your system not make use of an inverter? Where my fridge currently sits it has 12v leads necessary to run the 12v heating element (mine is so old it doesn't have a board running an auto light, etc.). Unfortunately, PleasureWay insists there's no build manual available for consumer consumption (hard to believe on a RV like mine that's 20yrs old). Also are you running AGMs or Lithium? I assume the former since I've read that one of the advantages to Lithium was it's ability to charge faster. And, last, did you upgrade your alternator?

Again, thanks for the very helpful info. It IS much appreciated.

Glenn

We do have a big inverter, big alternator(s), 300 watts of solar, and a 440ah AGM battery bank, but for other reasons than just running the frig. We want longer off grid/no sun capability and with microwave and some other higher draw things being used.


For the frig you just need batteries and charging sources. In testing before we built the big system, we used 260ah of wet cells with 200 watts of solar, standard Chevy alternator with 80 amps to the coach, and a 40 amp shore charger. For 1-3 day stays, we were almost always just fine as long as we didn't run high load things like the surround sound system on the TV, that used 10+ amps. If we would have gotten low, an hour drive would give back a days use. We did get 3 days of rain and heavy shade once, and at 3 days were in need of a charge, but still a ways from dead.

[GallenH]

Booster: Perfect. Thanks for all of your information. It dawned on me that I read a thread on electrical where you and a few others were designing some type of split system where low AH lithium was used to top up AGM. How did that turn out? I got to the end of the first thread where you were going off to test it. Did a new thread start up after that?

thanks again.glenn

[booster]

Originally Posted by GallenH

Booster: Perfect. Thanks for all of your information. It dawned on me that I read a thread on electrical where you and a few others were designing some type of split system where low AH lithium was used to top up AGM. How did that turn out? I got to the end of the first thread where you were going off to test it. Did a new thread start up after that?

thanks again.glenn

Harry has a thread going on the hybrid system he put together, and by all accounts is working well. A couple of others are considering trying to do similar. He does have a thread going on his system.

[booster]

Links to the hybrid AGM/lithium discussions


http://www.classbforum.com/forums/f2...stem-7451.html


http://www.classbforum.com/forums/f2...read-7658.html

[GallenH]

Thanks booster. Got it.

[DWorrell3]

I have a 2012 RoadTrek 190 and one of the first things I did was replace the Dometic with a NovaKool compressor refrigerator. Fact is, the expansion frigs will only cool about 40 degrees below ambient. So, if it is 100 degrees out, expect your Dometic to read around 60 degrees. My NovaKool will hold 35 degrees, no matter what. It runs on a/c and has an internal inverter that allow it to run on dc. When boondocking, I can get at least three days on the refrig through the coach batteries, and much more than that if I hook up my solar suitcase unit. I have heard, indirectly, that most of the RV mfrs are actively considering using only compressor units in their future vehicles. Hope this helps. Dave W

[Roadtrek Adventuous RS1]

Originally Posted by DWorrell3

I have a 2012 RoadTrek 190 and one of the first things I did was replace the Dometic with a NovaKool compressor refrigerator. Fact is, the expansion frigs will only cool about 40 degrees below ambient. So, if it is 100 degrees out, expect your Dometic to read around 60 degrees. My NovaKool will hold 35 degrees, no matter what. It runs on a/c and has an internal inverter that allow it to run on dc. When boondocking, I can get at least three days on the refrig through the coach batteries, and much more than that if I hook up my solar suitcase unit. I have heard, indirectly, that most of the RV mfrs are actively considering using only compressor units in their future vehicles. Hope this helps. Dave W

Dave,

This is our batteries bank...we have two of these in series...

https://www.battsys.com/centennial-b...id-agm-battery

We also have a 160 watt ZAMP solar panel ....specs below....

ZS-US-160-30A-DX KIT SPECS:

24.85 lbs
58.3” x 26.4“ x 1.5”
160-Watt Power Output
Generates 8.7 amps
25-Year output warranty
30 Amp Solar Controller

If I were to run a refrigerator like yours....how long would I be able to do that??

I could also run the engine to augment the power... but, this would be a pain when I'm away from the unit...,

I like the idea of having cooling ...35 to 38 degrees constantly sounds very nice.

Suggestions or ideas????

[booster]

The Novakool will likely use between 25 and 60 AH per day, depending on the weather and the quality of the installation, particularly venting. How much you open it will also have some effect.


Just work that much power use into whatever you use now, and you will be able to know how long you can run without charging.


On a very good solar day, you will get maybe 45 AH of harvest, which would cover the frig, but take that power away from what you use for other stuff.


You have 224ah of battery so at 80% drawdown you would have 180ah usable IF the batteries were totally full (per a good, well setup battery monitor) when you started. You will more likely have about 150ah available because you won't be full when starting drawdown.


We go over this all the time with many different folks on here, and the results are always the same. If someone believes the folks that have compressor frigs when then say how good they are, and get one, they are essentially never disappointed or want to go back to an absorption frig.

[markf57]

Originally Posted by DWorrell3

I have a 2012 RoadTrek 190 and one of the first things I did was replace the Dometic with a NovaKool compressor refrigerator. Dave W

Which model did you get to fit the Roadtrek?

[Roadtrek Adventuous RS1]

Originally Posted by markf57

Which model did you get to fit the Roadtrek?

I have the original Domestic 8501 , 3 way refrigerator...came with my rig from the factory...

Working fine normally at lower elevations and on electric...

Problem is extremely high temperatures.....

Found out today that I have no cooling fans in the cabinet...

Domestic said that would be helpful.... Roadtrek doesn't install cooling fans with their installation.

[BBQ]

Originally Posted by Roadtrek Adventuous RS1

I have the original Domestic 8501 , 3 way refrigerator...came with my rig from the factory...

Working fine normally at lower elevations and on electric...

Problem is extremely high temperatures.....

Found out today that I have no cooling fans in the cabinet...

Domestic said that would be helpful.... Roadtrek doesn't install cooling fans with their installation.

Lots of instructional video on youtube; it is an easy install.

[Knit]

My 2103 Roadtrek RS has a Norcold DE0788 refrigerator that runs off 12v DC or 120v AC when available. No propane. It has 220 Ah of AGM batteries and 200 W of solar. It all works pretty well together and it has never had a problem lasting overnight. We rarely stay in the same place more than one night so battery gets some charge when driving and some from solar. We don’t see the need for more battery storage the way we use it.

When I was a kid, my parents RV had a propane/120v refrigerator and I remember it being a real PITA. It’s really nice being all electric for refrigeration.

We have had problems at ~10,000 ft at near freezing temps on both the propane space and water heating. Thank goodness the propane cooktop has always worked for that morning coffee.

[davdent]

We have a 59g Travato with the larger 3 way absorption fridge. We have travelled extensively at high altitude both in way below freezing and most recently in the current heatwave conditions. The fridge has been faultless. I do suspect it is harder to start on gas in hot weather though.

We only use battery when driving or stopped for short periods. Never 110. We tend to stay in what we would call the scrub so use gas most of the time. We get 4 weeks out of a tank. We are very careful to level the van and use an iPhone app to make sure we are under 3 degrees. Preferably 2 degrees. The fridge is very cold and the freezer frozen solid.

I have read on this forum over many months opinions that would differ from this and I have to disagree absolutely. I would choose this type of fridge again for the ability to get it away from it all for an extended period. We have used an absorption fridge in a Jayco previously and again it worked perfectly.

We had a chat to a couple with a 59k in Yellowstone 3 days ago and they lamented on their 12/110 fridge that wasn’t keeping things cold and they had to use an ice container to keep things cold.

It would be accurate to say that my experience differs from what I have read on this site on this topic.