My Experiement with the Factory Solar

[GOUSC]

I’ve seen a few posts where people ask how long can you boondock using the factory solar. I realize the answer depends on how much electricity you use. I recently added a 3rd 90W Zamp solar panel to my roof, as a supplement to the original 2 installed with the factory solar, and decided to test some things from July 1 – 6, 2020 with my 2018 Globetrotter, (GT), parked in my driveway. Our factory solar includes the 2 AGM lifeline batteries. I’ve read where people have their batteries drain pretty quickly from the parasitic drawer, much less adding the propane refrigerator into the equation. I thought I’d just try an experiment in trying to recreate our uses on our GT over a 5-6 day period with the

When we first got our GT, we took a 5-week trip out West and about 50% of our time was boondocking. I recall when we were at Horsethieves BLM near Moab, UT we went 5 days boondocking. At that time, I only had 2 solar panels and carried a Honda EU2000 with me. I used the Honda for our microwave and to top off the batteries when needed. I used my generator about 2 hours over the 5-day period.

Since then, we’ve gotten better at our energy usage and I don’t carry the Honda generator anymore. I’ve replaced it with a Yeti Goal Zero 1000 to save space and not have to carry around a gas can. I can recharge it with the cigarette lighter adaptor when driving during the day or from location to location or, with electric when not boondocking.

For Boondocking I would say we are minimalists when it comes to energy usage. We don’t need the television or radio as usually there are no channels to be picked up. We use a Chemex pour over for our coffee so we don’t need electricity for a coffee maker. We use a Yeti Goal zero rechargeable lithium battery light inside and out. We use 2 Opolar USB rechargeable fans for next to our bed or wherever we need to move air. I have a Ryobi portable fan for moving larger amounts of air (it also can be run by electricity when we have that). I use a Bose Bluetooth speaker for music with my Ipod. Our use is generally the refrigerator / water pump / water heater / cook top / oven / limited inside lights as during the day we are usually outside doing something

5 -7 days is usually our boondocking limit as 7 days is about the max we can stretch out our water and holding tanks if there is no other water source. I can’t (didn’t want to take the time) recreate all of our uses. However, here is what I did to try and simulate that.

I started with batteries at 100% and 12.9V 1st thing on the morning of July 1st after unplugging the electric the night before. I had our refrigerator run on propane full time, in addition to whatever parasitic draws normally occur. I never normally use my inverter since I have the Yeti GZ 1000. However, I know it draws a lot of power so I turned it on each day for 1 – 1 ½ hrs. along with the TV and the TV antenna booster around noon. I figured this would put a pretty good draw on the batteries that may simulate our other uses.

My parking spot at home gets shade in the morning and from around 3:30 in the afternoon on. I figure I get around 5 hrs. of direct sunlight each day. Every day was sunny except for July 5th where we had rain for a couple of hours in the afternoon. I did my test from July 1st thru July 6th since that is our normal boondocking period. I monitored the batteries at least 3 times each day to see how they were doing. I kept a log for each time I checked buy I won’t bore you with that.

During this time, I observed;

I had 42.3 of Solar amp hours charging.

The lowest the batteries registered were 55% and 12.5V after the rain and the inverter had been running.

The lowest voltage noted on the batteries was 12.4V.

The most common low readings were 70-75% and 12.5V before the solar kicked in.


Quite a few times the batteries registered 12.5V but the solar was not kicking in to charge (solar is supposed to kick in when they drop below 12.7V. One trick I tried to get more solar to kick in was to turn on the inverter. Once I did that, the solar kicked in to charge. I would then turn off the inverter immediately.

Once I reached July 5th, it seemed to me that solar was doing what I would need for boondocking. However, I still have my Yeti Goal Zero as a backup in case I don’t have enough sun and need to give a boost to my batteries. I switched my refrig from Auto to propane only. I then used my Yeti as an alternative power source to charge my batteries for an hour, from 5:00 – 6:00 pm. Before charging, the solar monitor registered 70% battery state and 12.4V. I used 233 watts of my Yeti’s 1,000 watts for this charge. After this the solar monitor registered 100% and 13V for the batteries.

The morning of July 6, the solar was not charging. The batteries registered 12.4V on the battery terminal. Later that morning, 8:40 the solar was charging and batteries were 100% and 13.1V. At 10:35 a.m. after the solar charging the batteries were 12.7 at the terminals and on the solar monitor. This indicated to me that my 1 hour of the Yeti charging the day before gave the batteries enough of a boost to get to their 12.7V and 100% state of charge.

This seemed to indicate to me that this setup seems to work for our boondocking purposes. If we have a lot of rain, things may change. However, if I’m boondocking and I have rain for 4 days I’m probably gonna hitch up and move.

I shut down everything around 2:00 on July 6th and hooked back up to electricity. My Boondocker converter showed 14.6V in the initial hookup. This is it’s normal initial rate. It eventually settles on 13.2V when it is in float mode. At 6:15 pm is was at 13.6V. The following morning it was at 13.2V.

The only other items to note with the Yeti. We use it to microwave our oatmeal or oat bran for breakfast and to grind our coffee beans at breakfast. For this, I turn my breaker off for the converter. This prevents the Yeti from using power to the converter. It then allows me to use the Yeti for these 110V purposes. We only use the microwave for 3-4 minutes and the grinder for 1 so it does not use much power from the Yeti but allows us to spoil ourselves a little while boondocking. My wife can also use her hair dryer is necessary at evening.

The only thing I would like to upgrade at this point would be to the Victron Mppt 100/300 solar controller to get better charge rates in all types of weather. I will say that I would probably agree with others that with a new trailer, it would be a better move to have a 3rd party do the solar if you find a reliable person in your area to do the work, after you decide what your needs are. Since technology changes so fast, its hard to know what to build in to plan for the future. Lithium is all the rage now but what will it be in 2 years?

If you are a high tech / high energy usage camper this will not work for you. However, if you like to keep things simpler it might be an alternative. The Yeti Goal Zero 1000 was $950 (they go on sale randomly for $750 if you can wait). The additional solar panel was $360. The install was pretty straight forward. Attach with 3M VHB ¾” tape for each of the 4 mounting bracket. Cover those brackets with Sikaflex 221 white adhesive / sealant to keep moisture out. Clean the spots on the roof with a non-alcohol based cleaner.

[JonDNC]

Thanks, I too have factory solar and added 2 additional panels but never tested the, the way you did. I now have more confidence it will do the trick when we are off grid.

[Hans627]

Jim,

A very interesting study and report. Thanks for taking the time to do the research and explain the what and how!

[lsbrodsky]

Very thorough, nice. I did a much smaller scale, similar test after I installed Lithium, inverter charger, additional solar, Victron controllers, etc. I did my test at Shenandoah National Park. What I learned was obvious to a casual observer. There is too much cloudy weather and trees in the Eastern mountains to give you enough solar. I even have a large portable that I moved around trying to catch some sun. Still, I made it four days before I had to run the generator. We needed the furnace every morning to warm things up. I don't do that often enough to merit more Lithium batteries so I feel I have the right mix.
In the end, my grey tank was the limiting factor and you do not dump it on the ground at a National Park!
Larry

[ghaynes755]

Nice review. Not sure where your Victron is located in relation to your batteries. On my Classic it was at the opposite end of the trailer. Victron documentation and most installers will locate the charger as close as possible to the batteries to reduce current loss.



Lithium solutions in RV's have been out for over 9 years at this point. (see the articles and videos from the folks at Technomadia). The biggest change, not really a change in technology, has been new players like BattleBorn entering the arena. Doesn't seem to be anything new on the near horizon and the prices have not changed very much as demand has grown. Those that say prices will be dropping have been saying that for 9 years .


I am on my 4th solar setup. (3 Airstreams and a motorhome) 3 of those systems were Lithiums. All systems done by Marvin Braun from www.precisionrv.com. Current setup is 1000w on the roof of my Classic 33, 600ah of Elite Power Solutions batteries, Victron charge controller and Magnum 3000w Hybrid inverter/charger.

[jeffmc306]

GOUSC, thanks for sharing your experiment results!

I doubt we’ll ever get too far off the grid so your approach with the 3rd panel and the Goal Zero 1000 is a great alternative to going “all in” on Battle Born and full Victron. I’m waiting to see the updated versions of the larger GZ units; they’re supposed to have larger inverters. Fingers crossed...

Thanks again!
Jeff

[uncle_bob]

Hi

Be very careful of battery capacity derived from voltage readings. There are a *lot* of things that can mess you up doing that. Battery voltage is temperature dependent and you have voltage offsets due to current flowing in wires. Depending on the current and the temperature, you can be off either in the high or low direction ....

Bob

[GOUSC]

One other item I just purchased is a Blaux portable A/C, 89.99 + $8.95 shipping. Got good reviews. It looks to be around 5-6” square and operates cordless with a lithium rechargeable battery. Just pour in a little water and you get 8 hrs of run time. I think it will be perfect to put on the nightstand between to 2 twin beds at night for the few times it is too warm and you need AC in a boondocking situation. Since it is portable the possibilities are endless.

Can’t wait for it to come in and try it.

[GOUSC]

Originally Posted by Hans627

Jim,

A very interesting study and report. Thanks for taking the time to do the research and explain the what and how!

Thanks Hanno - you be able to do better with single Battleborn and even better if you can get them to work out the 2 smaller versions to fit in the battery box. Keep me posted!

Jim

[GOUSC]

(Quote Nice review. Not sure where your Victron is located in relation to your batteries. On my Classic it was at the opposite end of the trailer. Victron documentation and most installers will locate the charger as close as possible to the batteries to reduce current loss.

Thanks - I don't have the Victron yet but would like to upgrade if I can figure it out. I have a FB twin model and the current solar controller in under the right front side bed in the DC distribution box so it is close to the batteries. The problem with the 2018 GT is there is an access panel but all you can do is look at the DC distribution box and inverter but there is no way to move / pull out or otherwise get acess to anything in there. They changed this is 2019 to allow a removable panel to fully access everything there.

To change that, it looks to me I have to remove the center nightstand / the full panel that extends across the front and then cut the off the part to allow access and support with cleats underneath. It just appears to be a really bad design. I have some warranty work at JC later this month. I understand JC is not having an option for the Victron 100/300 mppt controllers as a option. I'm debating on whether to get them to install this at that time or do it myself at a later date.

[Sport 16 STL]

GOUSC,
Nice write up and thanks for sharing. We have the same 2-90 Watt Zamp panels. We replaced our solar controller with a MPPT Renogy and built a 200W portable suitcase. Batteries are two 3 year old stock Interstate 12v. We have no TV and have done well boondocking for 4-5 days without using the suitcase. With any sun at all our grey/black tank is our main limiting factor. Only once we camped in heavy shade, ran the furnace a bit at night did we "run out of Battery" at 12.2V. I wish the interstates would die but the solar controller does a great job in maintaining them. Will replace with one lithium.
Question- do you have the goal zero connected to the 12 or 120V circuits on your trailer or do you use it as a freestanding unit? Thanks again for the information.

[Tomfeury]

very interesting.
I was totally unaware of the YETI solution and I will look into it.
Right now, I use the 160w factory solar augmented with the zamp 230W portable suitcase.
We mad it through 5 sunny days at Asseteague by taking showers and washing dishes at the camp bathroom. Othrwise the tanks would have held us back also.

Thanks for sharing!

[GOUSC]

(Quote) Question- do you have the goal zero connected to the 12 or 120V circuits on your trailer or do you use it as a freestanding unit? Thanks again for the information.

Mine is a freestanding unit. I got all my information for this from Pteck and his "affordable approachable lithium" post.

https://www.airforums.com/forums/f37...-196422-8.html

He uses a 30-amp transfer switch connected the 120V circuits in his Airstream. In his situation, it looks like he as space under his refrigerator to house the transfer switch and his Yeti 1000. There is no such space under the GT refrigerator. I believe the reason is there is a storage cabinet above the refrigerator. If that cabinet was not there and the refrig was raised higher I believe it would be possible.

The 50-amp transfer switch appears to me to be much larger. I believe I may be able to use the storage under my couch, (which is next to the 12V / 120V panel to store everything there but I'm not willing to give up that storage space.

I have been keeping my Yeti in the back of my pickup bed that has a tonneau cover on it. When boodocking I obviously don’t have 50-amp service. When I want to use my yeti inside the airstream I flip the breaker to my converter and connect a regular extension cord to this 50 amp to 20 amp connector. The Yeti then powers all my 120V appliances (except for air conditioner) inside my airstream. When it is raining you need to make sure the Yeti stays dry. I can close my tonneau cover and just run the extension cord over the tailgate and under the cover.

My next step is to store my Yeti at the foot of my twin bed on the curb side. There is room on the floor. I have fished wire from my circuit panel under the refrig / under the shower to the access panel on the back of the shower near the floor. I will connect the 14 guage wire to a vacant 12V circuit and run power to a Cigarette lighter socket that I will attach to the plywood panel wall beneath the shower (there is vacant space below the shower I can access thur the removable access plate. This will allow me to travel with the Yeti in my airstream and charge it in route thru the tow vehicle umbilical cord and with any solar with the Yeti cigarette lighter input while we are in route. Should be no shade on the interstate.

[GOUSC]

Originally Posted by uncle_bob

Hi

Be very careful of battery capacity derived from voltage readings. There are a *lot* of things that can mess you up doing that. Battery voltage is temperature dependent and you have voltage offsets due to current flowing in wires. Depending on the current and the temperature, you can be off either in the high or low direction ....

Bob

If I understand you correctly, I think you are saying that the battery % on the factory guage may not properly reflect the true battery %. I that is the case, I wish I would have remembered to check the voltage at the battery terminals and compared it to the voltage inside each time, but I did not. However, I did do so at the beginning and end.

It bothered me at the end that the inside battery voltage was 13.1V and the battery % was 100% but the battery voltage at the terminal was 12.5V because I know that 12.5V is not 100%. The 13.1V battery and solar voltage on the monitor had to be due to the current solar voltage why the solar was charging. This was at 8:40 a.m.

However, by 10:35 a.m. the batteries were at 12.7V at the terminals and the monitor after 3.8 amp hours of solar charging. this seemed to indicate the controller knew the batteries were under 12.7V and it charged them enough to get them raised from 12.5V to 12.7V. I believe 12.7V is considered 100%.

Now, I don't believe this 12.7V really equated to a 100% battery that would be charged by my 60 Amp boondocker converter. However, during this entire time everything worked and got me thru my 6 day boondocking experience until I go to dump my holding tanks / refill my water / recharge my Yeti and go to my next boondocking spot.

Does this sound correct or, in the ballpark?

[Sport 16 STL]

GOUSC,
I already added a 12volt plug. Mostly for better cord arrangement while charging but will try charging items. It will probably be a slow charge, maybe faster inside the tow vehicle.
When using the yeti, you trip the converter to avoid using the power to charge the trailer batteries?
About the only time battery voltage is accurate is in the middle of the night. No solar and minimal power draw, batteries tested.
Thanks for the information.

[GOUSC]

Originally Posted by Sport 16 STL

GOUSC,
I already added a 12volt plug. Mostly for better cord arrangement while charging but will try charging items. It will probably be a slow charge, maybe faster inside the tow vehicle.
When using the yeti, you trip the converter to avoid using the power to charge the trailer batteries?
About the only time battery voltage is accurate is in the middle of the night. No solar and minimal power draw, batteries tested.
Thanks for the information.

When using the yeti, you trip the converter to avoid using the power to charge the trailer batteries? Yes. All your 12V stuff still works off the house batteries, including solar charging of them. The Yeti then powers all 120V except for HVAC. If you are boondocking you should be OK to leave it that way. However, when you get full hookups your batteries will not charge until you turn your converter back on at the panel.

As I noted in my experiment - you can use your Yeti to charge your batteries with the converter if the fuse to the converter is on. Not the most efficient way to charge them but when you need the batteries charged it is the same as using your generator to top them off.

I'm also sending you a PM with a question for you.

[cicho69]

I have the factory solar on a 2020 w/Lifeline batteries. My charge comes on @ 12.4v. I reach 13.1v /100% and the system shuts off. After a bit the voltage is at 12.8v both at the batteries and the wall mount and it reads 100%. About 1-2 hours later I'm at 90% and I then seem to settle at 85% for most of the sunny day. The use /store switch is off and the propane detector is also off (as when it's on a led indicator light comes on). My question is: What else could be drawing these batteries down?

[GOUSC]

Originally Posted by cicho69

I have the factory solar on a 2020 w/Lifeline batteries. My charge comes on @ 12.4v. I reach 13.1v /100% and the system shuts off. After a bit the voltage is at 12.8v both at the batteries and the wall mount and it reads 100%. About 1-2 hours later I'm at 90% and I then seem to settle at 85% for most of the sunny day. The use /store switch is off and the propane detector is also off (as when it's on a led indicator light comes on). My question is: What else could be drawing these batteries down?

There are many more people on this forum more knowledgeable than I on this subject and hopefully they will chime in. I will offer one suggestion that may affect this. It may not be what is drawing on your batteries but whether your batteries are charged to their fullest to start with. I upgraded the factory stock converter to a Boondocker 60 Amp converter and have noticed a big difference in the charging of my batteries since then. I think others have upgraded to a Progressive Dynamics converter with similar results. I just don't think the stock converter gets the job done like these others do.

Maybe try searching on this topic and see if this answers your question.

[uncle_bob]

Originally Posted by cicho69

I have the factory solar on a 2020 w/Lifeline batteries. My charge comes on @ 12.4v. I reach 13.1v /100% and the system shuts off. After a bit the voltage is at 12.8v both at the batteries and the wall mount and it reads 100%. About 1-2 hours later I'm at 90% and I then seem to settle at 85% for most of the sunny day. The use /store switch is off and the propane detector is also off (as when it's on a led indicator light comes on). My question is: What else could be drawing these batteries down?

Hi

All the voltages that you read on a battery are temperature dependent. They charge by 1/4 to 1/2 a volt up or down as you go from cold out ( high voltages ) to hot out ( low voltages ). Right at 70F on the battery, the numbers on a chart are correct.

Your magic "capacity readout" gizmo would need to be temperature compensated to correct for this. That involves a temperature probe *on* the battery. It also means that the compensation needs to match the specific chemistry of *your* battery.

Since most people do not go to the trouble of installing a probe and even fewer have setups that can be adjusted for chemistry, voltage monitors are simply a guess (even under perfect conditions).

What are perfect conditions? Well, the battery needs to be at rest. Not charging, not discharging, not changing temperature rapidly. It needs to be in that state for at least a half hour and better yet an hour or two. You need to have it read at the battery terminals with no voltage drop on the leads. You also need a properly calibrated monitor. In real life, your monitor never operates under perfect conditions.

The answer is to get a shunt based battery monitor. They look at current in and current out of the battery. That's the only way to really know what's going on.

=====

Things that drain your battery: The inverter may pull as much as 1/4 amp when off ( 0.1A is more typical). Your sub-woofer may pull some current. The propane detector pulls very little compared to these two.

Bob

[Imustwander]

This is a factory solar question. I apologize if this has been covered in another thread. I've searched and can't seem to find an answer.

I have factory 90W solar on my 2020 23' GTFBT. I also have a 140W Zamp solar suitcase. If I plug the suitcase into the Zamp solar sidewall port, would the batteries be able to receive charge from both panels? Would I effectively have 230W of solar in a sunny location?

Thanks!

Thanks!