Reply
 
Thread Tools Display Modes
 
Old 07-30-2019, 02:56 PM   #101
Platinum Member
 
Join Date: Jul 2018
Location: Minnesota
Posts: 512
Default

Quote:
"Sorry to break it to you but that is a pretty basic PWM controller IMO."
Which is probably totally appropriate in a pretty basic PV solar system to handle the pretty basic function of delivering power for lights and a refrigerator. He will likely lose some energy under some conditions but its doubtful it will have any significance.

Quote:
It's similar to the type of controller I'd buy at around $20
Its also similar to $125 controllers which appears to be what this one is priced at. You probably wouldn't buy those either. You would buy an MPPT controller because those are the newest guys on the block. That would be better but in this context is probably overkill.
__________________

RossWilliams is offline   Reply With Quote
Old 07-30-2019, 04:49 PM   #102
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 8,045
Default

Some more thoughts:

RA_RS1 uses the Title line often when posting and I suspect many of us don't notice that line.

One of his Title fields had this:

Quote:
It would just be an overnight situation..
If his goal is only to get through a mild temperature overnight stop and then drive again the next day then his proposed setup should handle that without issue assuming typical use consisting of lights & pump etc.. Winter use could be a problem but I doubt that he camps in very low temperatures. I'm referring to when it is cold enough that the batteries lose significant capacity combined with a near continuous heating requirement.

IMO maybe he's being misled by some reps and suppliers. None seemed to have explained to him that choosing a PWM controller would lower the output of the solar setup. A 170W Zamp panel (9.2A at 18V) will probably end up actually only delivering around 7A to the batteries at peak with the PWM controller. If you think of it as now being or functioning as 130W panel you probably wouldn't be too far off in your calculations.

It would appear that none of the reps or suppliers explained that power usage by the Nova Kool R3800 will vary. Assuming it uses a Danfoss BD35F compressor then the current use can range from 1.5A to 6.5A.

He probably has one of those relatively high current use separators under the hood so it's unlikely, IMO, that the input from the solar setup will cover the power consumption of the fridge. I'd expect a minor net loss there even on the best performing days. That doesn't seem to be a primary concern for RA_RS1 though. It appears that he won't mind cycling the batteries continually and just replacing them when needed. It's not a bad plan - in return he'll get convenience and ease of use with the new fridge.
__________________

__________________
Two bikes on sliding cargo box: https://www.classbforum.com/forums/m...icture206.html & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications: https://www.classbforum.com/forums/f...vana-5864.html
markopolo is offline   Reply With Quote
Old 07-30-2019, 05:19 PM   #103
Platinum Member
 
Join Date: Jul 2018
Location: Minnesota
Posts: 512
Default

Quote:
It would appear that none of the reps or suppliers explained that power usage by the Nova Kool R3800 will vary.
What causes the variation in amps being drawn? I assumed the compressor is an on/off operation, either drawing full current or almost no current. At least, aside from a surge when kicking in.

Update: apparently the variable speed compressors save energy by adjusting to run at lower speeds to maintain temperature. So they run longer, but draw less current which makes them more efficient. If the Nova Kool does that then it will actually use less power than he is projecting. But its specs don't say anything about that.
RossWilliams is offline   Reply With Quote
Old 07-30-2019, 05:35 PM   #104
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 8,104
Default

Quote:
Originally Posted by RossWilliams View Post
What causes the variation in amps being drawn? I assumed the compressor is an on/off operation, either drawing full current or almost no current. At least, aside from a surge when kicking in.

Evaporator and condenser temperatures both can affect the running amps the Danfoss.

I put that information in a thread somewhere with the compressor spec chart just a little while ago. I will try to find it. Efficiency will also change, and it is opposite of lower amps, surprise!

Other thread is here

http://www.classbforum.com/forums/f5...pecs-9459.html


This was also linked early in this thread.
booster is offline   Reply With Quote
Old 07-30-2019, 09:24 PM   #105
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 1,600
Default

My Isotherm 85 with a Danfoss BD35F compressor with an electronic thermostat, the Smart Energy Controller varies compressor speed.
https://www.indelwebastomarine.com/i...nergy-control/
GeorgeRa is offline   Reply With Quote
Old 08-01-2019, 01:36 AM   #106
Silver Member
 
Join Date: Sep 2018
Location: California
Posts: 53
Default

Data: Winnebago Paseo, 100 Watts solar, 2 @ 105 Amp hour AGM batteries. MaxxAir fan on thermostat, 86F turn on. Nova Kool RFU6200 refrigerator/ freezer on warmest setting. All windows covered, full sun, 70F to 90F clear SoCal weather.

Experiment: 12.7 volts at about noon. Four days later at 0600, down to 10.5 volts.

Conclusion: Iíll need more solar, or battery, or run generator if I want to boondock for more than a couple days.

Your Mileage Will Vary.
mikeehlert is offline   Reply With Quote
Old 08-01-2019, 02:13 AM   #107
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 8,104
Default

Quote:
Originally Posted by mikeehlert View Post
Data: Winnebago Paseo, 100 Watts solar, 2 @ 105 Amp hour AGM batteries. MaxxAir fan on thermostat, 86F turn on. Nova Kool RFU6200 refrigerator/ freezer on warmest setting. All windows covered, full sun, 70F to 90F clear SoCal weather.

Experiment: 12.7 volts at about noon. Four days later at 0600, down to 10.5 volts.

Conclusion: Iíll need more solar, or battery, or run generator if I want to boondock for more than a couple days.

Your Mileage Will Vary.

Thanks, all information we see is good for the record. Those numbers do make sense, especially if the batteries are a bit old or weren't at an absolute 100% full. Solar would give maybe 120ah back, fan use maybe 80ah, frig use maybe 240ah. So net at 210 + 120ah available and 80+240ah used so within 10ah of each other.


This is the real world stuff we need in the record for folks to see.
booster is offline   Reply With Quote
Old 08-01-2019, 04:06 AM   #108
Platinum Member
 
BillsPaseo's Avatar
 
Join Date: Mar 2018
Location: WA
Posts: 165
Default

Mike, running your batteries that low will reduce their life expectancy. 12.1V with no load is about as low as you want to take them.
__________________
2017 Winnebago Paseo
BillsPaseo is offline   Reply With Quote
Old 08-01-2019, 05:57 AM   #109
Platinum Member
 
Knit's Avatar
 
Join Date: May 2013
Location: CA
Posts: 172
Default

My understanding is that the original poster has two 6v 224 amp-hour batteries in series. This results in having a battery system that is 224 amp-hours at 12v.

I have a 2013 RS that has similar batteries, 200W solar, and a Norcold model DE0788 AC/DC refrigerator installed as original equipment and find it to be a good combination of battery, solar and refrigeration for our needs. And one less vent to the side of the van.

Our Victron battery monitor rarely shown less than 80% SOC in the mornings when starting with a fully charged battery. This is over 60k miles all over the west. We do avoid super hot places during the summer, though.

Grew up in RVs that had 3 way refrigerators. Always found dealing with the propane refrigerator to be a PITA. Compressor refrigerators rock.
Knit is offline   Reply With Quote
Old 08-01-2019, 01:00 PM   #110
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 8,104
Default

Quote:
Originally Posted by Knit View Post
My understanding is that the original poster has two 6v 224 amp-hour batteries in series. This results in having a battery system that is 224 amp-hours at 12v.

I have a 2013 RS that has similar batteries, 200W solar, and a Norcold model DE0788 AC/DC refrigerator installed as original equipment and find it to be a good combination of battery, solar and refrigeration for our needs. And one less vent to the side of the van.

Our Victron battery monitor rarely shown less than 80% SOC in the mornings when starting with a fully charged battery. This is over 60k miles all over the west. We do avoid super hot places during the summer, though.

Grew up in RVs that had 3 way refrigerators. Always found dealing with the propane refrigerator to be a PITA. Compressor refrigerators rock.

More good information, and monitor confirmed . You must not use a lot of power beyond the frig and get pretty regular sun so matches your solar and battery bank well.



How much driving and/or shore power do you do? Stay in one place long?
booster is offline   Reply With Quote
Old 08-01-2019, 05:02 PM   #111
New Member
 
Join Date: Jul 2015
Location: Texas
Posts: 17
Default

I switched out to a NovaCool 18 months ago and never looked back. I have a 2012 RoadTrek Popular and the OEM expansion fridge just didn't cool more than 40 degrees under ambient with DC power, either with the engine running or off the coach batteries. That meant if it was 104 degrees in Lubbock, TX, the fridge couldn't cool below 64. Shore power was marginal, but OK.

Now, I can maintain 36 degrees in any climate. The unit has internal inverter, so it will run off DC, either coach or engine power. Without shore power, no generator, I can get three full days with the fridge on coach batteries. I think the days of expansion refrigerators are limited. Dave W
DWorrell3 is offline   Reply With Quote
Old 08-01-2019, 08:01 PM   #112
New Member
 
Join Date: Mar 2018
Location: Mass
Posts: 10
Default Nova kool 5810

Have nova kool 5810
90 degree heat works great
Freezer 4 degree fridge 38 not cheap but fantastic
Tonycamco is offline   Reply With Quote
Old 08-09-2019, 02:08 AM   #113
Silver Member
 
Join Date: Sep 2018
Location: California
Posts: 53
Default

Quote:
Originally Posted by BillsPaseo View Post
Mike, running your batteries that low will reduce their life expectancy. 12.1V with no load is about as low as you want to take them.


Yes I know. My return was delayed a day.
mikeehlert is offline   Reply With Quote
Old 08-09-2019, 04:25 AM   #114
New Member
 
Join Date: Apr 2019
Location: CO
Posts: 1
Default

I have a NovaKool 4500 in my 2004 Leisure Travel. Two lifeline 6V 220AH in series for a total of 220AH at 12V. 200 watts of Renogy solar panels on the roof with Bogart Engineering SC2030 solar controller and BE TM2030 Trimetric monitor so I can view exact amperage going in or out of the battery. It also uses a very accurate algorithm to show the exact percentage of charge in the battery (look it up on the Bogart engineering website if you are curious). NovaKool states that the running amps are 4.4 but I see around 3.4. The compressor refrigerator is not designed to use outside air to reject the heat from the condenser coil. It should have inside air with adequate ventilation as stated in the installation instructions. When I replaced the gas absorption refrigerator, I sealed up and insulated the outside vents but left them removable for access to the compressor and controls. I also insulated the van interior outside wall where the refrigerator is installed. two weeks ago I was dry camping 4 nights at 9100 feet elevation. It was overcast over half of the day every day. Ambient temperature was mid 50s by morning and low 80s in the afternoon. During the whole trip, I ran the generator around 20 minutes total. The battery never got below 87%.
ripaco is offline   Reply With Quote
Old 08-09-2019, 02:15 PM   #115
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 3,481
Default

Quote:
Originally Posted by ripaco View Post
The compressor refrigerator is not designed to use outside air to reject the heat from the condenser coil. It should have inside air with adequate ventilation as stated in the installation instructions. When I replaced the gas absorption refrigerator, I sealed up and insulated the outside vents but left them removable for access to the compressor and controls.
This does not sound optimal to me. I agree that these units don't require outside venting (because there is no combustion). But that doesn't mean that they wouldn't benefit from it. The heat has to get out of the van somehow. Better to use the existing vents if you have them (although I certainly wouldn't install them if you don't). Otherwise, you are just heating up the van interior needlessly. I guess that could be an advantage in the winter, but when the A/C is running, you are just pumping the "same" heat twice.
__________________
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now!: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline   Reply With Quote
Old 08-09-2019, 03:10 PM   #116
Silver Member
 
Join Date: Sep 2018
Location: California
Posts: 53
Default

Quote:
Originally Posted by avanti View Post
This does not sound optimal to me. I agree that these units don't require outside venting (because there is no combustion). But that doesn't mean that they wouldn't benefit from it. The heat has to get out of the van somehow. Better to use the existing vents if you have them (although I certainly wouldn't install them if you don't). Otherwise, you are just heating up the van interior needlessly. I guess that could be an advantage in the winter, but when the A/C is running, you are just pumping the "same" heat twice.


Good observation. I would preserve the air intake and exhaust using outside air in summer and inside in winter.
mikeehlert is offline   Reply With Quote
Old 08-09-2019, 03:24 PM   #117
Platinum Member
 
Davydd's Avatar
 
Join Date: Aug 2007
Location: Minnesota
Posts: 4,695
Default

Compressor refrigerators are designed for a controlled environment which outside air is not. If you winter camp you may have a difficult time keeping contents from freezing drawing in outside air. On the flip side, if you leave your air conditioner off as we many times do and endure close to 90 deg. weather, you stand a chance of not keeping your refrigerator under 41 degrees.

You still have to have a controlled environment in back of the refrigerator so adequate air movement and insulation from radiant heat build up in the outer van wall is still critical. In fall, winter, and spring if heat is on the inside recirculation of venting is a bonus and you don't have a cold leak to heat. In the summer, or air conditioning need, I don't think it makes much of a difference in pumping the heat twice. It is still better than leaving vents to the outside in an uncontrolled environment where your refrigerator has to work harder in hot weather. So, you pay for it with air conditioning or refrigerator running more. I will leave that for some other person to work out.

Another advantage to compressor refrigerators when designed originally, is you don't have to deal with the two vents on the outside in regard to maintenance and appearance.
__________________
Davydd
2015 Advanced RV Ocean One Mercedes Benz Sprinter
Previous Class Bs:
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter
Davydd is offline   Reply With Quote
Old 08-09-2019, 04:40 PM   #118
Platinum Member
 
Join Date: Jul 2018
Location: Minnesota
Posts: 512
Default

David - I think you are spot on. The heat taken out of the refrigerator is coming from somewhere in the coach. So trying to vent it to the outside is essentially trying to use your refrigerator to remove heat from the coach aka air conditioning. You are better off letting your air conditioner do the job it is optimized for. As soon as the compressor shuts off, the "vent" is going to leak your air conditioned air out and let heat back in.
RossWilliams is offline   Reply With Quote
Old 08-09-2019, 06:57 PM   #119
Platinum Member
 
Join Date: Dec 2017
Location: Arizona
Posts: 452
Default

So from this discussion about venting: What do the current mfgs of RVs that have compressor fridges as stock do with regard to venting? Are there no exterior vents to the fridge compartment? I believe I read somewhere on this forum that space on the inside beneath the fridge is vented on some but honestly can't remember.
GallenH is offline   Reply With Quote
Old 08-09-2019, 07:10 PM   #120
Platinum Member
 
Davydd's Avatar
 
Join Date: Aug 2007
Location: Minnesota
Posts: 4,695
Default

Quote:
Originally Posted by GallenH View Post
So from this discussion about venting: What do the current mfgs of RVs that have compressor fridges as stock do with regard to venting? Are there no exterior vents to the fridge compartment? I believe I read somewhere on this forum that space on the inside beneath the fridge is vented on some but honestly can't remember.
Advanced RV has always installed compressor refrigerators. Air intake is at the base and exhausted at venting at the top. ARV installed two small computer fans to boost air out which also cooled the microwave sitting above the refrigerator. It did not have vent openings to the exterior.
__________________

__________________
Davydd
2015 Advanced RV Ocean One Mercedes Benz Sprinter
Previous Class Bs:
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter
Davydd is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 03:54 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×