28 replies to this topic

[Andy Douglass]

Nice write up and conversation in this thread.  And those weld mount studs and cable managers are a good find.

 

Did you bond the panels to the polycarbonate sheets at all?

 

Also, with your air springs/compressor setup....what monitors the pressure in the air springs?  Is it done by the compressor?

Edited by Andy Douglass, 17 July 2017 - 02:58 AM.

[Esus]

Did you bond the panels to the polycarbonate sheets at all?

 

Also, with your air springs/compressor setup....what monitors the pressure in the air springs?  Is it done by the compressor?

 

I did bond the panels to the polycarb sheets. I used a JB Weld product that had a really high temp rating. In hindsight, I don't know that it was necessary though. Bolting them down to the weld mount studs would prob have been sufficient. 

 

The compressor/wireless controller constantly monitor and adjust the bags. I thought I was being clever initially by wiring it so that I could use it without the vehicle turned on. Rewiring it is on my todo list now. It's so sensitive that when I jump out of the camper in the middle of the night to pee for example, just that small weight difference will activate the compressor briefly. It disrupts the peace and quite of camp and must be mildly annoying to neighbors. Not to mention that if I ever got a hole in one of the bags the compressor would probably kill my battery if it wasn't caught fairly quickly. 

[Andy Douglass]

I did bond the panels to the polycarb sheets. I used a JB Weld product that had a really high temp rating. In hindsight, I don't know that it was necessary though. Bolting them down to the weld mount studs would prob have been sufficient. 

 

The compressor/wireless controller constantly monitor and adjust the bags. I thought I was being clever initially by wiring it so that I could use it without the vehicle turned on. Rewiring it is on my todo list now. It's so sensitive that when I jump out of the camper in the middle of the night to pee for example, just that small weight difference will activate the compressor briefly. It disrupts the peace and quite of camp and must be mildly annoying to neighbors. Not to mention that if I ever got a hole in one of the bags the compressor would probably kill my battery if it wasn't caught fairly quickly. 

One thing I thought of when you wrote that was the possibility of springing a leak when you are away from the truck and draining the battery/burning out the compressor.

[Will.I.Am]

Esus...since your panels are in series, wondering if that 50W panel you have is limiting the amps those 120W panels produce, since you're in series?  Or do the additional volts cancel that loss out?

[Esus]

Interesting. I did this so long ago I had to do a little research. I think you're correct. In series with different panels, the one with the lowest current will limit the others. That means my 50 watt panel is dragging the entire array down to 4.17a. Multiply that by 36v (12v*3 panels), and I'm limiting my 290 watts worth of solar to 150 watts! Oops. If I were to rewire it in parallel I'd end up with my full 290. How embarrassing. Rather than rewire in parallel which would be a real pain, I think I might just exclude the 50 watt panel from the circuit. That way I end up 240 watts without doing much work. Thanks for pointing that out!

[Will.I.Am]

Well, I did the exact same thing... I have two 120 panels and a 50, which were wired in parallel with a Trimetric charge controller, then bought a Victron MPPT for various reasons and serial wired the panels, but realized the 50 was holding the total wattage back.

[Esus]

The most interesting take away from the error is that I definitely over sized my system. Apparently ~150 watts is adequate for my needs since I haven't had a single power issue, summer or winter, for several years worth of camping. I don't even bother connecting it to the truck for charging since the solar has worked so well. 

[Will.I.Am]

That is interesting.  Not sure which Dometic fridge you have, but we find that our CR1110 is running quite a bit in warm weather, and has a really hard time getting back up to temp if I pull a few beers out (or put like 2 warm ones in).  Sometimes, it can't catch up till the middle of the night and runs most of the day in the 50F's.  The 240W of panels keeps pace during the day, but because the fridge can't catch up till night, our 125AH Lifeline AGM gets drawn down to around 70% or less sometimes.  Even in full sun, our 240W of panels take a long time to get the system back to full.  We're starting to think about replacing our front opening fridge with a Dometic CFX 74 or other top loader, and turning the fridge space in the camper into storage (drawers probably).  Anyone have any experience with the CFX line?

[Esus]

I don't know the model off hand, but it's a compressor style running exclusively off 12v. I like my beer when I'm camping and am constantly swapping warm cans in without any issues.