Silly Solar Panel Question 🌞😎

[eric1514]

Better (more expensive) roof vent fans have a thermostat along with a rain sensor installed. I just set mine for some temp and it comes on during the day and goes off at night. If in the off chance it rains, it closes. Upgrading your vent fan might be the easiest solution.

[avanti]

Originally Posted by Urlauber

I generally leave the lid open. It has a cover with a screen, so nothing bad should get in there. Doesn't rain much here and when it does, it's strictly vertical, so no issues with water intrusion really.

I was thinking of something cheap and simple like this. Any thoughts on why that would not work? Looks good to me so I should be receiving it tomorrow. Cheap enough to play around with!

Looks ok to me.

Not sure what you mean by worry about battery management. The idea is to use the excess solar electricity to power the fan which keeps the interior cool. On a cloudy day the fan should not run, on sunny days the solar PV will produce enough energy to keep the batteries topped off plus the fan running for part of the day. The thermostat could be adjusted accordingly to not empty the batteries.

If you are confident that you could arrange never to cause your battery to discharge fully, that's fine. I personally would not want to trust the "dead reckoning" approach that you describe. I would want some kind of shutoff sensitive to SOC.

[Urlauber]

Originally Posted by avanti

Looks ok to me.

If you are confident that you could arrange never to cause your battery to discharge fully, that's fine. I personally would not want to trust the "dead reckoning" approach that you describe. I would want some kind of shutoff sensitive to SOC.

Gotcha, thank you. Yeah I would not want to "store" it that way, but parked in the driveway it is fairly easy to monitor which way SOC is heading. I think the solar panel provides for enough energy to run the fan for say 6-10 hours a day on low (~1A, maybe), with lots of buffer for cloudy days and dust and bird crap on the panel.
Should get the thermostat tomorrow (incredible) so I will report back on how this turns out.

Apart from some vampire drain, which should be offset by the solar panel, is there an other reason to NOT have the main cabin switch on all the time?

[avanti]

Originally Posted by Urlauber

Apart from some vampire drain, which should be offset by the solar panel, is there an other reason to NOT have the main cabin switch on all the time?

Well, my preference is to have the main switch turn off everything EXCEPT the few things that I want connected to the battery all the time (In my case: solar, Trik-L-Start and SOC meter). That way, I can just flip the switch to "off" when not in use without having to think. The exceptions have their own breakers.

[Urlauber]

Originally Posted by eric1514

Better (more expensive) roof vent fans have a thermostat along with a rain sensor installed. I just set mine for some temp and it comes on during the day and goes off at night. If in the off chance it rains, it closes. Upgrading your vent fan might be the easiest solution.

True, but I am a penny-pincher, so $10 to add a thermostat sounds just so much better than $400 for an upgraded fan. Maybe when/if the existing fan breaks.

[Boxster1971]

Originally Posted by eric1514

Since the van is parked outside in the sun, could you use the electricity to run some fans to help keep it cooler inside?

That is what I do in the heat of summer. My MAXXAIR Deluxe fan has a thermostatically controlled variable speed option. I open one of the awning windows to let air in. I usually set it to stop fan when van interior gets to 80 degrees after sunset. My 400 watts of solar handle this plus keep all batteries fully charged for week or more when parked in my driveway. Only down side is it can draw in some extra dust since the incoming air is not filtered.

[Urlauber]

Originally Posted by avanti

Looks ok to me.

Would someone please check my wiring ideas?

Planning to use a DPDT switch to 0=turn it all off 1=use the fan as it is now and 2=use the Thermo Controller (purple) to automatically run the fan.

The green thing is the existing 0-1-2-3 switch.

My concern is: when switching to the current way, there will be some voltage going to the output side of the Temp controller. Not sure how that thing looks inside and if that may confuse it or blow it up, or if there is an internal relay so it won't care about what's going on outside.

[avanti]

Originally Posted by Urlauber

Would someone please check my wiring ideas?

Planning to use a DPDT switch to 0=turn it all off 1=use the fan as it is now and 2=use the Thermo Controller (purple) to automatically run the fan.

The green thing is the existing 0-1-2-3 switch.

My concern is: when switching to the current way, there will be some voltage going to the output side of the Temp controller. Not sure how that thing looks inside and if that may confuse it or blow it up, or if there is an internal relay so it won't care about what's going on outside.

The Amazon page has pictures of the inside. Looks like there is a relay.
Also, the two black wires are internally interconnected, so there is no point in switching them.

I would just wire it all with a common ground and use a SPDT switch to either provide power directly to the fan circuit or through the stat. If it is indeed a relay, you can just "wire or" the line from the switch and the one from the relay in parallel. Even if it were electronic, it would very likely be a high- impedance output and would work anyway.

[Urlauber]

Originally Posted by avanti

The Amazon page has pictures of the inside. Looks like there is a relay.
Also, the two black wires are internally interconnected, so there is no point in switching them.

I would just wire it all with a common ground and use a SPDT switch to either provide power directly to the fan circuit or through the stat. If it is indeed a relay, you can just "wire or" the line from the switch and the one from the relay in parallel. Even if it were electronic, it would very likely be a high- impedance output and would work anyway.

Thank you! Yep now looking at the images I see the relay as well.
I just happen to have a couple of DPDT switches sitting around, but yeah, SPDT would save some wires. I guess I could just bridge the two "black" connections on the switch to turn it into a SPDT version.

[Urlauber]

Alright! It's done!



I decided to chicken out and keep it super simple - skipped the switch altogether. The only situation when it would be needed is when I want to run the fan with temperature below the trigger point. Like when sbd is cooking and smoke density reaches -cough- certain levels. Note the little thermistor sticking out cheekily.



In that case I can just lower the starting point which takes just a couple of seconds. Long push -- push push push push (it increments in 1/10 degrees) push push push push and there.
I used the existing screw hole to attach the temp controller to the fan casing. No obvious modifications in case I regret stuff and want to do something else.



Right now I have it set to turn on at 28C (actually it turns on at 28.1) and off at 26.5C. Works really well so far!
As I had mentioned somewhere else, I can spot the road when opening a drawer.



I figured, when you've got lemons... so I covered it with chicken wire and some coarse cloth.



So now the critters have some resistance to entering the cave, and I only need to open the drawer a bit to get some cool air to flow in.
We'll see how it works out, but should be a good way to keep the temps a bit lower than what they would be without it.

Thank you!