Another BigFoot Solar Thread

[MyronL]

Yeah, I would definitely always want to boondock.

I recently added a solid framed 190 watt solar panel to my roof. Thought hard about flexible panels, really did not want to drill holes in the roof. In the end I could only find 100 watt flexibles and did not want to add two panels up there. Gave in and drilled holes at the corners for the holddown bolts. No regrets.

[MyronL]

My work here is done. It is looking like I have found an alternative to propane and running the fridge (Dometic RM8551 4.3 cu ft) while towing, or anywhere the sun shines.
Here is what I got:

• One each Lithium Battleborn 100ah
• One 190 watt solar panel permanently attached to trailer roof and connected.
• One Victron 100/30 solar controller.

At 11 am this morning in yard it was 70°F in fridge, 85°F in trailer. Full sun outside. I fired up fridge on battery, 4 dots. Battery was at 13.6 V. Also just for fun, turned on inverter.

At 2 PM sun is on street side and inside the trailer it was 91°F. Fridge showed 54°F. And the Battleborn showed 13.5 volts. That would be 14 degrees cooler in three hours.

Quoting Sparky Anderson, you coulda knocked me over with a feather.

[ThomasC]

I just realized you made these two posts. I am glad that is working for you. Personally I would rather use propane to power the frig, just not while driving. I think the frig works better on propane, at least mine does.

So you last a tenth of a volt while the sun was shining. What happens to your voltage over night?

[BridgetMills]

Hi Tom, I'm curious if you have had enough time on the road to comment on the solar panel install. Is the combination of VHB and Eturnabond tape holding up? Have you ever checked the temperature of the panels under heavy output?

[ThomasC]

Originally Posted by BridgetMills

Hi Tom, I'm curious if you have had enough time on the road to comment on the solar panel install. Is the combination of VHB and Eturnabond tape holding up? Have you ever checked the temperature of the panels under heavy output?

I think I got a bad batch of VHB tape. I used it with eturnabond tape on the first solar panel. The last three were only eturnabond tape. I never checked temperatures.

I learned at that Victron seminar that the colder it is the more power you can get from a solar panel. It makes sense, I just never thought about it. Well it can be a problem up north and they have equipment to turn off over producing panels.

I have been about 4000 miles with the solar panels so I think they are stuck down pretty good.

[ThomasC]

I was up on the roof yesterday to give it a wash in preparation for some kind of wax job. Everything looked good and all of the Eturnabond tape is doing it's job. The only flaw was one panel shifted off of the plastic cardboard spacer that I used under the panels. It only shifted a quarter inch and maybe the spacer shifted and not the panel. I tried sliding them back inline but they are stuck that way now.

If I had to do it over now I would use double sided tape between the panel and the spacer.

I don't know what kind of coating they put on those panels but the water beaded up like they were a freshly waxed surface. The water was just sheeting off of the rest of the roof. I might not have noticed had I not just watched a Project Farm video on different paint protectors.

https://www.youtube.com/watch?v=uYxKQwZah1s

[ThomasC]

One of the reasons for this build was to be able to run the refrigerator on AC while driving. The first time I tried it I thought the batteries would stay at 100%. It didn't keep up so I used propane some of the time. Now that I am used to the system, I started out with a 66% of charge and after about 6 hours of driving I was in the mid 80s'. That is enough for TV and heat for a couple of days.

This morning I started out in the 60s' and after a full day of driving ended in the 90s'. There was very little sun today so it was all on the B-to-B charger. It will never get to 100% without good sun because as the voltage gets up there the charger tapers off the current going to the battery.

Anyway, it does what I want so I am happy. I will see how it goes at Quartzite in February.

Here is a photo of the Anderson connector suppling the B-to-B charger.

[John Razzo]

Thanks for the update. My Bigfoot 25RT has 2 lithium batteries and the solar (330 watts total) doesn't do too well keeping up with the demand when the fridge is on electrical. It requires lots of good sun and careful planning. If I forget to go back to propane in early to mid afternoon it could lead to a low battery that night.

As for driving with the fridge on AC I believe the battery/electrical system might hold it's own but have yet to fully test it. I do not have the DC to DC charge set up and at this point I do not want to go to the expense and time of installation. I also get the sense that the fridge might do better on propane. The temperature can be inconsistent in either mode and from what I can determine there is no way to adjust it. If it gets turned on in hot weather it can take a few days to get down to a desired temp.

[Perryb67]

Originally Posted by John Razzo

Thanks for the update. My Bigfoot 25RT has 2 lithium batteries and the solar (330 watts total) doesn't do too well keeping up with the demand when the fridge is on electrical. It requires lots of good sun and careful planning. If I forget to go back to propane in early to mid afternoon it could lead to a low battery that night.

As for driving with the fridge on AC I believe the battery/electrical system might hold it's own but have yet to fully test it. I do not have the DC to DC charge set up and at this point I do not want to go to the expense and time of installation. I also get the sense that the fridge might do better on propane. The temperature can be inconsistent in either mode and from what I can determine there is no way to adjust it. If it gets turned on in hot weather it can take a few days to get down to a desired temp.

The fridge is meant to be on AC only when you're at a site with power and DC is basically for when your propane is not working. To run on AC driving down the road or in a camping site without services you're using your inverter and that's even more inefficient. When driving down the road or not hooked up you should be using propane. With only 330 watts you'll probably never keep up. We have 465 watts on our roof and don't ever run DC and certainly not AC using our inverter. Perhaps if you had in excess of 1,000 watts on the roof it could keep up with your standard RV fridge.

You need a fridge with a Danfoss compressor to successfully keep up, but that involves removing your current fridge and buying a new Danfoss.

Enjoy,

Perry

[John Razzo]

Originally Posted by Perryb67

The fridge is meant to be on AC only when you're at a site with power and DC is basically for when your propane is not working. To run on AC driving down the road or in a camping site without services you're using your inverter and that's even more inefficient. When driving down the road or not hooked up you should be using propane. With only 330 watts you'll probably never keep up. We have 465 watts on our roof and don't ever run DC and certainly not AC using our inverter. Perhaps if you had in excess of 1,000 watts on the roof it could keep up with your standard RV fridge.

You need a fridge with a Danfoss compressor to successfully keep up, but that involves removing your current fridge and buying a new Danfoss.

Appreciate the feedback. I'm am a bit surprised that a decent solar system (ex: 400 watts) can't keep up with the Fridge during prime sunlight hours via the inverter. Also that the charging system from the tow vehicle is insufficient as well. I guess the AC demand for a little fridge is fairly significant. On the other hand, when on propane, the actual amount of propane used (and DC power consumed) is relatively small. Good info.

Thanks Again.

[ThomasC]

I am a little surprised at how my recent update was interpreted. My goals have been met. I am able to roll down the road with my propane off because of the B-to-B charger with a little help from my solar. My battery bank is more charged at the end of the day than at the beginning. A couple of the days have been really cloudy so, there was no help from solar.

I have been monitoring while driving with the Victron phone app. I get 25 amps from the truck all the time. If it is cloudy I will be running negative 3 or 4 amps when the frig is running. When it cycles off because it is cold enough I will be positive 25+ amps and charging the battery bank. My battery bank always builds up while I am driving. I have stopped for the night and it is at 92%. The fridge is working on propane now and since I made it into Georgia I might not need heat tonight. Heat is the biggest consumer when I am parked.

As far as when a fridge should be run on AC "I as in me myself and I" will decide when it runs on AC and when it runs on propane. There is hardly an inverter out there that can't handle 400 or 500 watts. When I am parked at Quartzite the fridge will be on propane and all of the solar will go to heat and TV. If I run low I have my generator just in case.

[oldwave]

Originally Posted by ThomasC

I am a little surprised at how my recent update was interpreted. My goals have been met. I am able to roll down the road with my propane off because of the B-to-B charger with a little help from my solar. My battery bank is more charged at the end of the day than at the beginning. A couple of the days have been really cloudy so, there was no help from solar.

I have been monitoring while driving with the Victron phone app. I get 25 amps from the truck all the time. If it is cloudy I will be running negative 3 or 4 amps when the frig is running. When it cycles off because it is cold enough I will be positive 25+ amps and charging the battery bank. My battery bank always builds up while I am driving. I have stopped for the night and it is at 92%. The fridge is working on propane now and since I made it into Georgia I might not need heat tonight. Heat is the biggest consumer when I am parked.

As far as when a fridge should be run on AC "I as in me myself and I" will decide when it runs on AC and when it runs on propane. There is hardly an inverter out there that can't handle 400 or 500 watts. When I am parked at Quartzite the fridge will be on propane and all of the solar will go to heat and TV. If I run low I have my generator just in case.

One of the things I did like on my old Escape was the Fridge was a three way: dc propane and ac

While I didn’t have that much Solar. One panel, and I had just stock lead acids, I could get 4 or 5 hours of driving with the fridge on dc and I lost some battery charge. I would expect with 400 amp hours of lithium and a high quality dc to dc charger, the fridge would run on dc quite awhile. I wonder if the 8 cubic foot fridge is available in a three way ?

[ThomasC]

Originally Posted by oldwave

One of the things I did like on my old Escape was the Fridge was a three way: dc propane and ac

While I didn’t have that much Solar. One panel, and I had just stock lead acids, I could get 4 or 5 hours of driving with the fridge on dc and I lost some battery charge. I would expect with 400 amp hours of lithium and a high quality dc to dc charger, the fridge would run on dc quite awhile. I wonder if the 8 cubic foot fridge is available in a three way ?

When I ordered the BF I asked for a three way and got no for an answer. It is just as well because the AC heater is around 400 watts. So, if you had a dc heater that was 360 watts you would need more than 30 amp fuse .

My inverter is supposed to be very efficient at lower levels so I am not losing that much.

[ThomasC]

First of all in my defense, I drive around with my headlights switched to automatic. I just get in and out of my truck and they turn on and off as needed. However, if it is bright out, they will turn off the parking "running" lights. So, I was driving with my parking lights on and when I stopped for the night they stayed on.

I got up with a dead battery in the truck and no jumpers. I am not the type of person to ask for help so walking around asking for a jump was out of the question. I also didn't want to wait for AAA.

I have batteries under the dinette seat but they are too hard to get out. OH wait a minute I have a 4 ga cable going from under the hood of my truck to the B to B charger on my solar installation. So I unbolted the cable from B to B charger and screwed it to a positive buss bar and started the truck.

The whole thing took less than 15 minutes. Cool!!

[Raspy]

Originally Posted by Perryb67

The fridge is meant to be on AC only when you're at a site with power and DC is basically for when your propane is not working. To run on AC driving down the road or in a camping site without services you're using your inverter and that's even more inefficient. When driving down the road or not hooked up you should be using propane. With only 330 watts you'll probably never keep up. We have 465 watts on our roof and don't ever run DC and certainly not AC using our inverter. Perhaps if you had in excess of 1,000 watts on the roof it could keep up with your standard RV fridge.

You need a fridge with a Danfoss compressor to successfully keep up, but that involves removing your current fridge and buying a new Danfoss.

Enjoy,

Perry

Perry stated this very well. Propane for normal use, 120 volts when you have hookups, 12 volts for emergencies only.

The Absorption fridges run on heat. One way or another you have to make heat for them to work. Making enough heat with a 12 volt electric heater is a poor choice, running a 120 volt electric heater, by connecting it to an inverter is ridiculous and will waste at least another 10% of the energy. Making heat by burning propane is the best way to do it.

With an absorption fridge, I would turn it on the night before we left and turn it off when we got home. The entire trip, every time, on propane. While at home, if I wanted to run it, i ran it on house current rom the shore tie. But never on 12 volts.

Now, with a compressor fridge, the system runs on 12 volts that operates a compressor, not a heater. Much less power draw. Be sure you understand the difference between a compressor fridge, like a household fridge, and an absorption fridge, that runs on heat.