How many watts solar/lithium batteries needed?

[koberudy]

We previously had a truck camper with 320 watts of solar and 2 agm batteries that would pretty much run our small compressor fridge indefinitely off grid (along with what the truck alternator contributed going down the road). Would love to have the same capability with the new Flying Cloud 23FB that we have on order. I think I read that the compressor fridge that will come in it is a Norcold 4500? Surely someone has already figured this out. How many watts of solar and how many lithium batteries should it take to be able to do the same thing with this rig? And I know it depends on how much other stuff we plan on running in addition to the fridge. But just basically what should it take to keep the fridge going, as a point of reference to start with and then go from there?

[field & stream]

There are so many significant variables that no reliable rules of thumb exist. Nevertheless, here is a hip shot guess: 2-300w of solar and and a minimum 200Ah of lithium batteries.

I think you mean the Nova Kool 4500. According to their specs it draws 4.4 amps while running and a reasonable assumption is that it will run 50% of the time (more with hot days and warm nights). So, those assumptions mean the fridge alone will consume over 50Ah per day.

Solar recharging is highly variable and really hard to predict. If you like camping in the woods, off peak solar and travel seasons, and catch a cloudy stretch then 400w of solar may not be enough to keep you going even a week.

[koberudy]

Thanks Field & Stream, this helps a lot. So am I catching you right that there are 300w single panels available, and I should need 2, for a total of 600w on the roof?

[field & stream]

Hi - I was recommending a minimum of 200 to 300 watts of solar panels, and suggesting that even more might be required (batteries too). Of course your budget is a factor, but once you are into the project additional panels don’t add very significant cost.

Solar panels come in many different form factors and you will need to do a specific layout for your rooftop.

[koberudy]

I found where I can buy a high quality brand of 190w panels and had tentatively thought to buy 2, giving me 380w, and 2 of the Battle Born batteries. You're right, budget is an issue. I'm hoping to start with that and we can add on later if necessary. Do you recommend having the 2 batteries stay on the tongue in the place designated or see if my dealer's service department can move them to the inside somewhere?

[koberudy]

Are there any other options to paying $800 each for the 100aH Battle Born batteries?

[field & stream]

There are others on this site who are a lot more knowledgeable than me, and I hope they add their thoughts.

I think your starter plan is good, and may be all you need. Having the batteries inside has a number of advantages (e.g. temperature related, tongue weight reduction, maybe less risk of theft) but will cost more; if you want more than two batteries in the future you will need to bring them in.

[KK4YZ]

Even on cloudy days solar will help somewhat. But If you’re into serious boon docking you should consider a backup generator for when solar isn’t enough. The dual fuel Champion 2500 is light and quiet.

[uncle_bob]

Hi

If you are out in the wide open spaces with no trees or hills in sight *and* it's a bright sunny day *and* the trailer is pointed the right direction .... solar is wonderful in the summer. Fiddle with any of those assumptions and you might be at < 10% of that ideal. This makes solar highly dependent on exactly where you are.

Simple answer with solar is to start tossing 100W panels up there and see how many you can fit. A somewhat cheaper approach is to measure things and figure out what you can fit and then order panels A "roof full" is always going to be best, no matter how big your batteries are.

Charging batteries as you roll along with a typical trailer means pulling power via the 7 pin connector. ( Yes you can do custom wiring ). The 7 pin might only give you 10A, you could get lucky and get 25A. It is very much dependent on your tow vehicle, your trailer, and how you drive. A DC/DC converter likely will be part of the mix for proper charging via the 7 pin.

If you are using up 50AH a day and drive 4 hours, 10A charging will *almost* make up for things. Sit for a week and that "charge while driving" drops out of the equation. How often do you drive? How long do you sit?

800 W of solar panels ( 8 100W panels) will be very difficult to fit on any AS. Indeed, 400W is a challenge on a 23 foot. 300W *might* give you 1.5 KWH in a day. After this and that, it's a pretty good bet you will make up for your 50AH and have a bit left over on a really good day. With our setup and campsites, really good days happen a couple times a month.

There are a lot of outfits that will sell you bits and pieces to do this. To a great degree it's a "you get what you pay for" sort of thing. A used solar panel will be cheap, it also may have some issues. A battery from "Uncle Bob's Finest Batteries" probably will save you some money. If you have a problem, finding Uncle Bob to get that warranty honored .... good luck .

If you are in the shade, 200 AH of lithium will run your 50AH a day fridge (and nothing else) for 4 days. Fire up the furnace and you can forget about 4 days. Turn on the inverter to run this or that for a while each day ... 4 days is history.

As you drive down the road, you may well get power both from the TV and from your solar. That could mean that a day's drive gets you well ahead. Spend that day in slow moving traffic mostly in the shade from that truck next to you and not so much.

If your converter charger is big enough, you can do pretty well plugged in for a bit. 200AH with a "30A" charger that only puts out 20A will get you charged in a bit over 10 hours. Go to something that puts out a legit 80A and you are done in < 3 hours. If "plugged in" means a generator, run time matters. Go to a 400AH bank and you double all those numbers.

So lots of variables and lots of rabbit holes to wander down.

Bob

[drbrick]

I'm no expert - however, we have 2x100amp SOK lithium batteries and 200w solar on the roof + we run 180w suitcase simply because we're on Vancouver Island BC (Canada) we boondock in areas that have tress :-) and follow the sun with the suitcase :-) This has worked well to maintain our charge level at 13.8 volts average 95% amps. We run everything (not AC) including 300w inverter for 110 appliances. We carry a 3500w Champion geny (run on LP) as backup (which now usually collects dust since we converted to lithium)

[gdavis57]

I have the same trailer, except 2021.
You can put 6 panels on the roof, no more. We also have 6 100ah Battleborn batteries and the bank is under the bed on the passenger side, near the front. When rolling, the system does do some charging through the plug to the TV.
My opinion is that you can count on 50% of the advertised capacity on a daily basis, and you can get some power generation even on cloudy days. However, I'm also taking a propane modified Honda 2200 generator as a backup. You'll see you can do more on this power budget than just run a fridge; you may need heating/cooling, and that's a big power budget item that can be handled with 6 panels.
Take a look at the LOLOHO videos on YouTube. Shameless plug--they used Ronnie Dennis of Airstreamnutsandbolts.com, and that motivated us to do the same thing after we did a lot of research anyway.
Search

[Escape21]

We also have a 23fbt on order for November delivery. Ordered the 90 watt solar and an additional 90watts on the roof. Discussion with the factory there are four (4) zamp ports up top and an additional zamp outside for suitcase type panels. The Zamp brand panel, I think labeled Obsidian is made for a curved roof and can add an additional 180 watts to the 23. Max total 360 but close to $4000.00 for the complete set up. As someone said, the roof is limited for number of panels. We currently have 190 watts solar and two 100 watt BB lithiums, rarely use electricity since our current refrigerator is gas/electric. We plan on using suitcase panels which can be more ideally faced toward the best direct sun if available. Our Honda gen will be our backup or a 2000 watt portable power supply such as EcoFlow Delta. We look excitedly to arrival of our 23 fbt and know you are also.

[Wazbro]

Yes there are many options for lithium batteries you could get a single 280ah battery. Costco has had lithium batteries $500-600 for 100ah.

[Taco Joe]

I managed to fit 560 Watts of solar on my 2012 23 FB and 400 Ah lithium for around $4500. I also have a 75 watt portable panel that I can set on the ground, but only bring it in the winter. I am somewhat solar advantaged doing most of my boondocking in So Cal near my home in San Diego. I had to swap the 120 to 12 converter to lithium capable.(https://www.bestconverter.com/) I am using a 40 amp MPPT solar charge controller. I did all of the work myself. Batteries are Renogy 2 x 100 and 1 x 200Ah. I may add 200 more in the future. The 1 x 200 is under the bed and the 2 x 100s are in the battery box, which I had to cut and rebuild to fit these batteries.

[Dennis C]

Originally Posted by Escape21

We also have a 23fbt on order for November delivery. Ordered the 90 watt solar and an additional 90watts on the roof. Discussion with the factory there are four (4) zamp ports up top and an additional zamp outside for suitcase type panels. The Zamp brand panel, I think labeled Obsidian is made for a curved roof and can add an additional 180 watts to the 23. Max total 360 but close to $4000.00 for the complete set up. As someone said, the roof is limited for number of panels. We currently have 190 watts solar and two 100 watt BB lithiums, rarely use electricity since our current refrigerator is gas/electric. We plan on using suitcase panels which can be more ideally faced toward the best direct sun if available. Our Honda gen will be our backup or a 2000 watt portable power supply such as EcoFlow Delta. We look excitedly to arrival of our 23 fbt and know you are also.

Good to hear that they added a fourth Zamp port to the roof. They’ve only had three ports in the past. I bought a Y connector from Zamp to allow me to plug two panels into the third port, so I’ve got 4 90W panels on my roof for a total of 360W in ideal conditions. I’ve got the older style Zamp panels, and they work well.

[switz]

Our 2015 23D has five 100 watt AmSolar panels on the roof and a 315 AHr lithium battery just forward of the street side wheel well. The entire system is under the side sofa platform with no loss of the OEM storage space or slide out mattress board. The information is displayed on a custom information panel above the sofa cushions but below the television on the refrigerator wall.

Our 2014 31’ Classic has ten of those 100 watt panels and a 600 AHr lithium battery under the front sofa. Due to the this being the third generation of equipment, the solar charger is inside the triangular cabinet on the sofa wall. The Information is displayed above the dinette seat and television on the refrigerator wall (see avatar). All of the other equipment is under the sofa with no loss of the original storage.

Both trailers have a propane only Truma instant on water heater, a Vitrfrigo 12Vdc Freon based compressor refrigerator/freezer and upgraded Dometic CU-434 oven/cooktops.

These are a more expensive system in each coach than some might want.

Both installations removed the OEM television antenna and replaced it with a round one that was useless so both are now gone. We stream TV is we really need a video fix. The 10th panel is where the round television was on the Classic. If roof access was not an issue, we could get one more panel on the roof of the Classic.

[koberudy]

This is the OP. Thanks for all of the good advice and insight. When boondocking we usually don't sit in one place for very long. We're moving more than sitting, so the TV charging aspect will probably help somewhat. Also I figure if traveling cross country we will get into a campground, or plugged up at someone's house, at least once every third night. And yes, a Champion dual fuel genny is definitely on my want to get list, eventually. We have a 2000w gas inverter/generator now, just don't like to haul gasoline.

[Wazbro]

Originally Posted by koberudy

This is the OP. Thanks for all of the good advice and insight. When boondocking we usually don't sit in one place for very long. We're moving more than sitting, so the TV charging aspect will probably help somewhat. Also I figure if traveling cross country we will get into a campground, or plugged up at someone's house, at least once every third night. And yes, a Champion dual fuel genny is definitely on my want to get list, eventually. We have a 2000w gas inverter/generator now, just don't like to haul gasoline.

You might be able to get a conversion kit for the generator you have.

[uncle_bob]

Hi

If battery charging is the only goal, then the generator really does not need to be very big. If your converter / charger puts out 50A at 12V, that's 600W. Even with this and that going on, an 800W generator likely would do just fine for that converter. In terms of fuel efficiency, generators "like" to run between half load and full load.

Sub 1KW is going to be a smaller and lighter generator. It can be a very quiet generator if you get the right model. Finding anything in the low power end of the market that runs on propane is a challenge.

Bob

[jftompkins]

We have a 2017 FC23FB with 2x6V AGM that gives us 110Ah useable battery charge and have had the same thoughts on dealing with the new compressor refrig - someday?. We use about 25-30Ah/day with just basics (no furnace fan). On a good sol day we make up about 40Ah with a Zamp 120W portable. Most of our dry camping is in dryer climates - more solar radiation. So IF/When we go with the compressor refrigerator would consider: a. Lithium upgrade to 200Ah+ in battery compartment only - for us we need inside storage maintained b. Max panel capacity on roof with MPPT controller for efficiency c. Pack portable panel(s) to plug in if necessary (Zamp port at trailer tongue rated at 20A) d. Hot days - keep refrigerator door closed. Attached are my estimated numbers….