Will This Solar Set Up Work For Extended Boondocking?

Greenhil

My 2022 320 CS S boondock is equipped with a 12 V flooded lead acid battery rated at 81 amp hours. It has the factory equipped 100w solar panel. I’ve discovered that camping off grid, this is just enough to run the Alde for 3 days for 5 or 6 hours at night to keep the battery above 50%. Other than phantom power, nothing else is drawing current. 

I’d like to improve this setup so I could do 5 or 6 days of de-winterised summer boondocking using the pump, fan and 2 way fridge.  I’ve read what I can here and elsewhere and I guesstimate this might use about 40 amps of power daily (which is pretty much the limit of my battery’s capacity, if I understand correctly). 

My questions are:

1. Realizing there are a lot of variables that affect solar performance and power use, can a 200w solar array (plus the T@B’s solar panel) fully charge the battery in a day, with decent sun at my New England latitude?  (On paper the answer seems to be ‘yes’ - Renogy says their  200w array provides 1KWH/83 amp hours per day)
2. Are there any kind of mismatch issues I should know about when connecting a 200w solar suitcase that has a 50 amp controller to my battery/system? 
3. Am I simply fighting a losing battle with the battery I have? I worry it can’t get me through one rainy day even if I cut back my power demands. 

I’m at the point where I’ve gathered just enough info to completely confuse myself, so if I’m speaking ishkabibble or if you have other suggestions, please let me know. Thanks!

MarkAl

It all comes down to how many hours will you get high angle sun on the arrays per day. Remember if you camp in winter the sun in northern states is much lower with less energy. 1 to 200 Amp*Hr Lithium will tide you over multiple days in rainy conditions. The amount of solar panel area will help more in limited Solar conditions to re-charge your batteries quickly during the day. There is no easy answer, it depends on forest cover, and sun availability where you normally camp.  You have a good estimate of your power needs per day (40 Amp*Hrs on the new 320) it either comes from your battery or sun. From my tag line you can see what I have but 6 days in the Pacific Northwest rain shadow cuts the battery very low, no amount of panels help me. Add a Victron Smartshunt to monitor power in and out of the battery. In addition add larger battery capacity. Also at least another 100 watt panel remote to allow positioning for sun.

qhumberd

So as a novice to boondocking with our 400 the "Unofficial Guide" attached has a nice section that might help in your decisions. He has a spreadsheet under boondocking decisions that has the current draw of each appliance (which will be the same or similar with your trailer) and then an estimate of the number of hours used to determine the total draw in amp hours from the battery over a 24 hour period. Then you can estimate (or measure with your controller) how many amp hours your panels will produce under typical conditions in a day, and that will be your recovery each day. If these are not in balance, then your battery will slowly loose capacity, and you only have 40-50 amp hours to work with to keep your battery healthy. My rough calculation of fan and frig and water pump based upon the sheet tells me that you would be hard pressed to make it 5 or 6 days. Would like to hear what others would recommend as well but for me more battery capacity seems the best answer.

WayneW

@Greenhil We went through the same thought process with our 2021 320S last year.  After using it for a season we decided the stock lead acid battery was always just on the fringe of getting us through our boondocking trips with little room for things like consecutive rainy days.  We upgraded to a 100ah lithium.  We already had a 100w Renogy suitcase from our T@G days to supplement the stock rooftop solar.  

I think getting a battery shunt of some kind is important.  The Victron SmartShunt is very nice but spendy.  I went with a hardwired Qwork shunt for $40.  Regardless, a shunt allows you to really see what's going on.  The Victron app for the stock MPPT solar controller also provides a lot of useful information.

Look for and eliminate as much parasitic draw as you can.  I removed the television since we never use it and installed a cutoff switch on the Jensen radio.  Parasitic draw is now in the range of 0.155 amps. 

The Fantastic Fan in stock mode draws quite a bit of power.  I did the $10 PWM mod that results in variable speeds.  Draw now in low speed is around 0.14 amps, 0.34 in medium and 0.9 on high.  I think the clamshell has a propane cutoff switch that draws a bit.  You can modify that to reduce power consumption. 

With our current setup of a 100ah lithium battery, rooftop 105w solar, 100w portable solar, and our frugal electrical lifestyle, I'm pretty confident we can get through long boondock trips even with suboptimal sunshine.  Time will tell.  We're soon heading out for 20 days with only a few stops that have electricity.

To answer your questions, I think a 200w panel would more than suffice.  There shouldn't be any issues with hooking up the panel.  And I think you might be fighting a losing battle with the stock battery and your desire to boondock for 5-6 days (or at best living on the edge).  That being said, there are people who have been happy with the stock battery setup and do just fine. 

CharlieRN

We also went through the same process on our 2021 320S BD.

We did some quasi-boondocking (Harvest Host camping) with the stock battery & solar adn found that it was tough. As you note, you typically use something like 40 amps in the course of the day, which is the limit for the stock battery. The roof-mounted solar can add some capacity back, but it is a challenge and you often are not parked with the panel properly oriented.

Our next step was to purchase the Renogy 200w solar suitcase to augment the factory system. While we were able to keep the battery topped up with the help of Renogy when it was sunny, a couple of days of overcast conditions led to the inescapable conclusion that the stock 80 amp battery is just too small. We changed to lithium late last year when Battle Born had their "blemished item" battery sale, and found that it was a big improvement. The improvement in nominal capacity is marginal (100Ah vs 80), but with lithium batteries, you can safely use 80 of the 100 Ah's, compared to only 40 Ah for the stock 80 Ah FLA battery. While LiFePO4 batteries have a higher acquisition cost than lead-acid types, they have a much lower lifetime cost, and are much better value for money.

A word about the Renogy solar suitcase. It can be used with the factory solar and 80 Ah FLA battery right out of the box, which is what we did for our first few camping trips There are no compatibility issues and you can connect via the SAE port if you change out the supplied alligator clip connectors. The output of the array should be enough to fully recharge the stock battery, assuming the right conditions, but I do not know this from experience. Unless things have changed however, the suitcase comes with a 20 amp PWM controller, not a 50 amp unit. Also, the stock Renogy cables are only 10' long, something that can prevent you from getting the panels to full sun. We replaced them with 30' cabling (10 AWG) and I also made up set of pigtails that allow connection via the SAE port or the alligator clip.

As others have noted, some folks are able to live just fine with the stock system. It does require that you are vigilant about energy however. My suggestion would be to take your time and see how you do with the stock system augmented with the Renogy solar suitcase. If you find that the 80 Ah FLA battery is not sufficient, you can then go with Li.

Denny16

On the TaB320, upgrading to 100 Amp Lithium battery would be the first step to increase your Boondock camping time.  A sub 90 Amp lead acid battery is good for camping in campgrounds with shore power, or a day or two of off Grid camping, but you need a larger battery with more AmpHrs available.  

Cheers 

Da_Birds

The propane cutoff switch is a very significant draw. You definitely want to either limit how long you keep the clamshell open or make sure you look into options to switch it off when it's open.  You can simply pull the 12V power cord from the TV when boodocking. I bring a small power bank with 12v port that I can run the TV off of for a couple hrs when boodocking. The fridge is by far the biggest drain on the battery so you need to be smart about how you pack it and and keep it adjusted.

We have a 130AH flooded battery and that gets us by for a 2 night boondocking trip. We need to be very frugal if we don't get decent sun but even getting some sun makes a big difference in how much the battery is drained at the end of the trip.

The problem with solar is it's only as good as the sun it is receiving and when your not getting sun it's useless. Then you're stuck with the limitations of your battery. I would personally focus more on how much battery power you have first because you can rely on it.

The analogy I like to use is that the battery is like a gas tank in a car and solar is like a gas station. If you're tank isn't big enough to hold enough gas to get you to the next gas station then you're going to get stranded.

Adding solar is relatively cheap and easy, which is why I think so many people look at doing that first, but throwing more solar at a small battery can be like trying to put 20 gallons of gas in a 10 gallon tank.

Greenhil

CharlieRN said:

We also went through the same process on our 2021 320S BD.

We did some quasi-boondocking (Harvest Host camping) with the stock battery & solar adn found that it was tough. As you note, you typically use something like 40 amps in the course of the day, which is the limit for the stock battery. The roof-mounted solar can add some capacity back, but it is a challenge and you often are not parked with the panel properly oriented.

Our next step was to purchase the Renogy 200w solar suitcase to augment the factory system. While we were able to keep the battery topped up with the help of Renogy when it was sunny, a couple of days of overcast conditions led to the inescapable conclusion that the stock 80 amp battery is just too small. We changed to lithium late last year when Battle Born had their "blemished item" battery sale, and found that it was a big improvement. The improvement in nominal capacity is marginal (100Ah vs 80), but with lithium batteries, you can safely use 80 of the 100 Ah's, compared to only 40 Ah for the stock 80 Ah FLA battery. While LiFePO4 batteries have a higher acquisition cost than lead-acid types, they have a much lower lifetime cost, and are much better value for money.

A word about the Renogy solar suitcase. It can be used with the factory solar and 80 Ah FLA battery right out of the box, which is what we did for our first few camping trips There are no compatibility issues and you can connect via the SAE port if you change out the supplied alligator clip connectors. The output of the array should be enough to fully recharge the stock battery, assuming the right conditions, but I do not know this from experience. Unless things have changed however, the suitcase comes with a 20 amp PWM controller, not a 50 amp unit. Also, the stock Renogy cables are only 10' long, something that can prevent you from getting the panels to full sun. We replaced them with 30' cabling (10 AWG) and I also made up set of pigtails that allow connection via the SAE port or the alligator clip.

As others have noted, some folks are able to live just fine with the stock system. It does require that you are vigilant about energy however. My suggestion would be to take your time and see how you do with the stock system augmented with the Renogy solar suitcase. If you find that the 80 Ah FLA battery is not sufficient, you can then go with Li.

Thanks, Charlie. This all makes sense and is the way we’ll go for now. You’re right - I misspoke - it’s a 20 amp controller. 

B11

@WayneW Thanks for your insights. Would you mind explaining the $10 PWM mod and how this change is made briefly?

The Fantastic Fan in stock mode draws quite a bit of power.  I did the $10 PWM mod that results in variable speeds.  Draw now in low speed is around 0.14 amps, 0.34 in medium and 0.9 on high.  I think the clamshell has a propane cutoff switch that draws a bit.  You can modify that to reduce power consumption.

WayneW

Re: the PWM mod:  Briefly (and I'm not an electrician so pardon any mistakes), the 3-speed setup in the stock fan uses a rheostat to change speeds.  This is inherently not energy efficient because it just dumps excess voltage as heat.  Plus I didn't like the stock fan speed options of Fast, Too Fast, and Hurricane.

The PWM (pulse width modulation) does something fancy inside that reduces voltage by varying the width of the on/off time the motor receives power.  For the mod, you bypass the rheostat and wire in the PWM to control fan speed.

The best explanation that I found of the mod is here:

http://ourelkhorn.itgo.com/camperII/fansw.htm

It has schematics and pictures that you can follow.  The mod results in a continuously variable speed fan.  It also retains the ability to reverse the fan.  It is much quieter, you can set it at any speed, and it's energy efficient.  You can do the mod from inside the trailer and there is no need to break any seals or caulking on the outside.  I hope this helps.  Good luck if you pursue this!

RogerC

WayneW said:

With our current setup of a 100ah lithium battery, rooftop 105w solar, 100w portable solar, and our frugal electrical lifestyle, I'm pretty confident we can get through long boondock trips even with suboptimal sunshine.  Time will tell.  We're soon heading out for 20 days with only a few stops that have electricity.

How did the 20 day trip go with regard to your electrical set up?

WayneW

@RogerC  It was quite a learning experience!  Biggest lesson learned - if there’s any sunshine I better grab it. We were moving almost every day and I didn’t always feel like setting up the portable solar panel. We lose about 20% battery capacity overnight. One day it was 70%. “Good enough,” I said. “I’ll make it up tomorrow.”  In the morning it was 50%, then clouds and rain for the next 2 days. We were limping along on life support. We only had 3 stops with electricity. I was counting on the second to finally recover. Then the tornado hit and knocked out power!  Therefore still limping along until we finally got some good sunny days. 

We’ve since been on an 11 day boondocking trip with no problems. Lesson learned - I set up the panel if there’s anything to be gained. All-in-all I’m still happy w our setup. I’m not looking to add any capacity of solar or battery. Our simple setup isn’t for everyone. It forces me to be a bit anal about energy conservation and getting the most out of the solar opportunities but I do like the simplicity. 

MarkAl

I just finished the update to a 30 amp VIctron Orion TR Smart DC-DC/Charger. We tend to stay 2-4 days in one spot then move on. If we have sun available in our site we grab as much as possible but the batteries do drop. We hike a lot during the day so can not fiddle with moving the remote panels. So with the charger and the roof I should get as much charge as the batteries will take as we move between sites. I don't have much practical experience yet on longer trips but this will help reset the batteries on longer travels. I know the TV charge is minimal without the added charger. Note this was not for the faint of heart electrically

AnOldUR

Just thinking. There's probably people out there already doing this. Could we come up with a removable attachment for our solar suitcase (maybe on the tongue box) where the panel could ride while traveling? Some way for it to be easily taken off and repositioned once reaching a destination. Wondering how much the exposure would shorten the life of the panel?

techietab

AnOldUR said:

 Wondering how much the exposure would shorten the life of the panel?

Probably heavily dependent on the panel brand and configuration. For instance, I'd never bother with this for my panels - an ultralight type that have minimal framing and only moderately water-resistant cordura-type fabric exterior trim and backing.

AnOldUR

techietab said:

Probably heavily dependent on the panel brand and configuration...

This was my thought also. Our Renogy suitcase has a fairly beefy frame and we use a Victron controller mounted in the tongue box. Still, the wear and tear from driving down the road may not be worth the extra charging gained?

Sharon_is_SAM

I would worry about road gators and rocks.

Greenhil

Thanks for the helpful responses. Just to bring my original post full-circle: I did purchase a 200w suitcase and have boondocked a number of times for several days running the 2 way fridge (and Alde heater) off my 81 amp hr battery. The suitcase and rooftop solar fully recharge the battery on sunny days. However one rainy day (or too shady campsite) is enough to force me to turn off the fridge to spare the battery. Eventually I’ll invest in a better battery, but I’m happy with the setup for now. I monitor my system using the Victron app, a shunt type battery monitor and multi meter - I’ve also eliminated phantom draws: unplugged TV, installed a power switch on the radio, disconnected the step light and I use a piece of garden hose to defeat the propane shut off switch in the galley kitchen.

Slackers

I like your garden hose hack for the galley propane shut off solenoid. Good job!