Proper setup for roof & briefcase solar panels on Micro Minnie

[IdahoHunter]

Just returned from a hunting trip in my 2108DS, and unfortunately found quite a few problems that I'll have to address with the dealership. This was the first trip of 10 days in all kinds of weather boon docking, and the solar charging was an area that I think needs improvement.

Purpose of this post is I didn't get the recharging performance out of my dual panel setup. I have a 200W briefcase with its own (admittedly a cheap "PWM Solar Charge Controller ) controller that's plugged into the aux solar port. It seemed like I should have gotten better recharging performance, and one symptom was the voltage readout on the briefcase controller jumped around. I also have to confess I haven't installed a smart shunt monitor yet (will buy Victron as part of this work), which means my "feeling" about battery charge status is based on the trailer panel idiot lights. However, I know from an outing with my wife that a fully charged set of AGM's would only drop to 2/3 charge after we both ran our CPAPs all night. On this trip, I was by myself, and let's just assume my gut feeling is right, and I'd like to know what is the better way to run two sets of panels.

The on board controller seemed to run well and display accurate info. Numbers were steady and seemed reasonable. The challenge is the trailer only got sun to its roof after noon on sunny days, which is why I have a briefcase setup too. I was able to set the briefcase where it got direct sunlight mid-morning through most of the day.

Spit-balling a series of questions I have. Does the output of the two different solar panel systems tend to fake out the other into believing the batteries have a higher voltage than they really do? Do I just need to run a better controller on the briefcase? Is part of the problem that I'm using a 25ft 16awg cable to connect the briefcase? Should I shift to one controller handling both panels?

That should be enough to get some ideas coming. Thanks in advance everyone!

[creativepart]

Here’s a concern. You are plugging the portable panel’s output into the side port on your 2024 Winnebago Micro Minnie 2108DS. But did you investigate how that port is connected to your trailer? Winnebago seems very changeable on this topic.

IF the Aux solar port on your TT is wired directly to the battery then what you are doing would be correct. However, sometimes Winnebago wires that Aux solar port directly to the TT’s existing solar charge controller. And if that’s how your TTis wired then you should not plug the portable solar suitcase into that port… because your solar suitcase already has a solar charge controller. You don’t want to plug one solar charge controller into another solar charge controller.

Perhaps you can share more about you TT’s existing solar setup to help fill us in.

One more thing, it’s a bit unnerving that you are relying on a “Dealer” for this work. Here’s hoping you mean a solar power dealer, not your run of the mill RV dealer.

[IdahoHunter]

I believe the solar port is in fact connected to the batteries. I measured the voltage on that port after I tripped the breaker that connects the battery to the on-board trailer converter. The measured voltage matched the battery voltage.

I'm not relying on the Dealer for my solar panel setup. I was referring to quite a few problems (aside from the solar panel configuration) that they will be getting for warranty work. I've got a technical background, and am soliciting input on this configuration to make the best decisions myself.

Any advice or ideas. Not much more to my setup beyond the 200W briefcase with the already named controller, and I have the on-board GoPower 30amp controller with the roof 200W panels.

[creativepart]

Thanks Mike, that explains a lot.

What kind of battery do you have, and how many amp hours?

A shunt will help you figure out your situation better, that’s for sure.

Best of luck with your dealer and warranty work.

[TravatoJohn]

Mike, I’m having the same issue with my 2017 Travato. My Zamp controller is the “PWM” type which I’m eventually going to change to the MPPT that Zamp offers. Surface mount. Several guys on YouTube show a 30 percent gain on power input. You didn’t mention your type on your rig only the additional solar portable unit. Creative gave you good advice. The portable unit (200watts) I purchased from Reology is without a controller and works great when plugged into the side port as my main controller can handle 500 watts total. I have 190 on the roof. Good luck. Travato John.

[IdahoHunter]

Some more info to help this discussion:

- I have two AGM batteries w/224cca each for a total of 448.

- The portable briefcase is a Serenelife 200W monocrystalline with a 20A PWM controller, which is rated to provide up to 10.8A and is 15A fused. Max output voltage of the panels is 18.6v with open circuit voltage of 22.8v I bought this briefcase after returning a Renogy 200W that was riddled with structural design flaws/failures.

- The onboard system is a GoPower 200W monocrystalline with a 30A PWM controller, which is rated to provide 9.6A with a 20.8v output and open circuit voltage of 24.3v. So, the output spec's on the two systems are a little different.

- I've turned off the onboard controller and have run the briefcase by itself, and it did charge the batteries fairly well by itself on a sunny day. So, the SAE plug on the side of the trailer is connected to the battery and is not a solar panel input to the onboard controller.

Since my first post, I've confirmed I should run a cable extension to the briefcase with a 10awg cable and not 16awg to reduce voltage drop/heating & subsequent restriction on current.

I've read for longer cable runs to portables, the controller (MPPT or PWM) should be located close to the battery. The higher voltage output of the panel would suffer lower voltage drop over the cable.

Since I have 400W of combined solar panel capacity, it's in the realm of when an MPPT controller will help. Plus, I go out outings when temps are at or below freezing, which is also when an MPPT controller is better. However, I am running two completely different makes of panels, which have different output characteristics. Many of the discussions I've read have suggested that would drive having two separate controllers so each controller could fully utilize each panel's capability. I get that, and am wondering if there is any reason I couldn't run an MPPT for the portable in parallel with the onboard PWM for the roof panels? Eventually I might convert the onboard controller over to MPPT also because of the low Fall & Winter temperatures. The output to the batteries would be electrically the same point.

Thoughts? I want to make changes before my next trip in mid-Nov, which will be up into the mountains where I will definitely see freezing temps potentially down to single digits.

[Marine359]

The best performance you can get from roof and portable panels is to NOT put them on the same charge controller. And of course mppt controllers work better than pwm. Victron makes very good controllers. A 100/30 for the roof allows you up to 400w of roof panels. And a 75/15 to service the portable. It’s only fifty bucks. This requires bypassing the portable panel’s built-in controller. Also, by putting in a second controller (near the battery), you can have a very long cable going to your portable without any significant voltage drop,. If you don’t already have a sidewall port, you can buy a SAE port cheap with a 3ft inside lead. That’s long enough to reach the controller if mounted amidships. Of course it’s always a good idea to route controller output to a fuse block. And also a good idea to put a manual reset breaker between roof array and the controller it will be connected to. Photos of the setup in my mods album.

[IdahoHunter]

Thanks Jim. Good succinct input. Your comments on this forum and the RV Life forum about this topic have been helpful. They contributed to my belief that putting an MPPT controller inside the pass-through was the way to go for the portable. Yes, I have a sidewall SAE port already. To route that to an MPPT controller inside, I'll need to find the routing of that port's cable. Shouldn't be a problem.

Did you use a 10awg cable for the portable pigtail? What lengths did you have? A 20ft would likely be enough in most situations, but wonder if extending that with a 2nd 20ft would work well too.

Appreciate your insight very much Jim!

[creativepart]

Originally Posted by IdahoHunter

I have two AGM batteries w/224cca each for a total of 448.-.

Sorry, but you do not have 448 ah of batteries. Cold Cranking Amps only count for starting an engine and do not apply to house batteries.
Depending on the battery group size you may have 120 ah, 160 ah or 200 ah at most. Those numbers are estimated on Group 24, 27 or 31 - the actual amount of amp hours is dependent on the battery you have. But CCA should be ignored when talking house (deep cycle) batteries

[IdahoHunter]

Originally Posted by Marine359

The best performance you can get from roof and portable panels is to NOT put them on the same charge controller. And of course mppt controllers work better than pwm. Victron makes very good controllers. A 100/30 for the roof allows you up to 400w of roof panels. And a 75/15 to service the portable. It’s only fifty bucks. This requires bypassing the portable panel’s built-in controller. Also, by putting in a second controller (near the battery), you can have a very long cable going to your portable without any significant voltage drop,. If you don’t already have a sidewall port, you can buy a SAE port cheap with a 3ft inside lead. That’s long enough to reach the controller if mounted amidships. Of course it’s always a good idea to route controller output to a fuse block. And also a good idea to put a manual reset breaker between roof array and the controller it will be connected to. Photos of the setup in my mods album.

A couple questions Jim. With the Victron Connect app to view the information from each MPPT controller, will I need a smart shunt battery monitor to view my battery status? From what I see about the app, it provides both charging status and battery status.

I'm also looking at a 100/20 for about $35 less because I don't see myself adding more solar panels on the roof. I suppose paying the extra money would at least keep my options open for a future addition if I find 400 watts isn't enough. What drove you to add more roof panels? I'm assuming your portable is a 100W or 200W.

[IdahoHunter]

Originally Posted by creativepart

Sorry, but you do not have 448 ah of batteries. Cold Cranking Amps only count for starting an engine and do not apply to house batteries.
Depending on the battery group size you may have 120 ah, 160 ah or 200 ah at most. Those numbers are estimated on Group 24, 27 or 31 - the actual amount of amp hours is dependent on the battery you have. But CCA should be ignored when talking house (deep cycle) batteries

Ha! Busted. I'm so used to saying CCA while dealing with car and truck batteries, that I wrote that out of habit. They actually are 224AH batteries. See pics below.

[Marine359]

A solar charge controller will only show you what’s going into the battery, and of course, it will only give you valuable information when the panels are producing. You still need a shunt to know everything going into and out of your battery. Regarding solar wire gauge, it’s always best to use 10 gauge wire, which can carry 30 amps, but just as importantly will have a low voltage drop over distance: like the distance you may want to place the portable panels away from the RV. I went with 30ft 10awg. On the inside of the SAE port, it should also be 20awg. The SAE port I bought had 3ft of 10awg on the inside; long enough to reach my 75/15 charge controller.

[creativepart]

Originally Posted by IdahoHunter

Ha! Busted.

“Ha” is right. Those are 6v batteries wired in Series to make 12v. So you have 224 ah of house batteries.

You double the voltage with series wiring not the amp hours.

You could wire them in Parallel and have 448 ah… but then you’d have only 6 volts, not 12v.

Also, 6v batteries have much thicker plates inside so they charge much slower. That very well could be why you are seeing it take so long to recharge via solar.

That’s a true deep cycle battery, but I’d expect to see them in an off grid residential house or “solar shed.”

[IdahoHunter]

Originally Posted by creativepart

“Ha” is right. Those are 6v batteries wired in Series to make 12v. So you have 224 ah of house batteries.

You double the voltage with series wiring not the amp hours.

You could wire them in Parallel and have 448 ah… but then you’d have only 6 volts, not 12v.

Also, 6v batteries have much thicker plates inside so they charge much slower. That very well could be why you are seeing it take so long to recharge via solar.

That’s a true deep cycle battery, but I’d expect to see them in an off grid residential house or “solar shed.”

I hang my head in shame. You are absolutely correct!

[The Raptor]

Hi Guys,

With my Calculations if a 12V Battery is actually 12.8V.
So, a 6V Battery should actually be 6.4V Rating ?!

So, 2x 6.4V 242Ah Batteries in Series should actually Calculate to 12.8V System.
Supplying 1'434Wh = 1'642CCA per Battery.
And provides 2'867Wh (2.87kWh) Stored Energy ....When New !


https://www.micropowergrids.com.au/C...alculator.html