Help needed! DIY solar ventilation.

[stevet47]

I recently got a new-to-me nissan versa which is quite an upgrade from my previous truck as far as MPG goes, but since it is black, it gets ungodly hot inside.

I have a solar panel from a VW, that I would like to use to power the cars blower fan to keep air circulating while it is parked (kind of like the new prius'). I know I wont have enough power to do much, but I think just keeping the air moving would help a measurable about.

My problem is how to tap into the blower fan.
If any electrical guru's could look over the FSM and let me know what they think, the help would be greatly appreciated!

Page 35 talked about the blower fan relay, which I think is my best bet for a place to tap in:
http://www.nicoclub.com/FSM/versa/2008_Versa/mtc.pdf

[Daox]

Yeah, you could tap in at the relay or the fuse box. It would probably be pretty easy if you got some fuse taps.

[stevet47]

I have used add-a-circuits before (similar to fuse taps). I was thinking going that route as well. I will probably experiment tonight.

My only concern with fuse taps/add-a-circuits is that I have only ever used them to take power to power something else. With this I need to put power into the curcuit to power it.

Ideally I would flip a switch, that would put the relay into the 'on' position, and instead of drawing power from the battery, it would draw it from the solar panel.

[Patrick]

How big is your solar panel? If it's not quite large, you may find that it doesn't have enough output to run the stock fan. Some people have used solar panels to power small muffin fans that were placed near the ventilation outlet (in the trunk) to try to move some air through the cabin. They don't move much air, but it's better than nothing.

Here's a link to one guy's adventure: http://www.cleanmpg.com/forums/showt...t=22764&page=4

[stevet47]

Originally Posted by Patrick

How big is your solar panel? If it's not quite large, you may find that it doesn't have enough output to run the stock fan. Some people have used solar panels to power small muffin fans that were placed near the ventilation outlet (in the trunk) to try to move some air through the cabin. They don't move much air, but it's better than nothing.

Here's a link to one guy's adventure: Solar powered cooling fan mod - Page 4 - CleanMPG Forums

That was my first thought, but I figured why go through the hassle of installing another fan when the car already has one.
The solar panel is 18.8V, 3.2W, 170mA. I dont know what the specs on the car's fan are, but I have powered other fans with it.
I can get another panel also, if I need it.

Thanks for the link, that will help me out a lot if I decide to go that route.

[Dr. Jerryrigger]

I would suggest the muffin fan too. But first do some tests.
If you have a good ammeter you can find out the wattage of your blower in different settings, and compare that to the PV cell.
The way I'd go about this is by jamming a loop wire in the fuse slot (if you want to be "safe" solder a fuse into this loop). Turn the ignition to acc or on (what ever is the minimum for turning the fan on). And test the current in the loop, and the voltage of your battery during the test. Test it at all fan speeds, and write down the findings. Then analyze with ohm's law:
I=V/R or R=V/I
P=I*V
I=amps, V= volts, R=resistance in ohms
P=power in watts
Then analyze with the voltage your PV cell puts out. If the wattage at that voltage is far greater than what you PV cell can do, then go with the muffin fan.

[stevet47]

I dont think my dmm has an ammeter, but I will have to check.
Thanks for the advise.

[comptiger5000]

There is no way 3.2 watts would power the car's vent fan enough to move any noticeable amount of air.

[Dr. Jerryrigger]

Originally Posted by comptiger5000

There is no way 3.2 watts would power the car's vent fan enough to move any noticeable amount of air.

Oh, I missed that, yeah, you don't have enough juice at all. If your going to do this you'd best go with another fan, and a very small one.
I'm worried this will not really help your problem though. I see it not changing the temp, and just making your car into a convection oven. If it was blowing in or out some where, like your main blower fan does it would be good.
If you can find blower type fan and hook it up to some old vacuum cleaner hose, you could blow the air out of an accessory hole in your fire wall. The slight vacuum would draw fresh air in threw the vents.
I can't seem to find a blower that small but I found this box fan: AD0612HB-A72GL ADDA Fans & Blowers
A shroud could be fabricated with a coffee can and some JB Weld...

[stevet47]

OK. So I may need to get another solar panel, not a big deal.

I am still going to investigate using the blower motor, but if that is too difficult or draws more power than I have, I will go with the computer fans.

Just like in the link Patrick posted, I would mount the fans to the flapper vents in the cargo area (hatchback) blowing out. The hope would be that it would pull the hot air out of the car, and fresh air would get pulled into the car through the HVAC vents via a draft.

The goal would be to keep the car as close to the ambient air temp as possible. Right now, it heats up like an oven in there.