[NoD~]

I have recently build a solar panel setup that will replace my sunroof. It should put out around 60w of power (18v+ from the panel, 13v+ from the charge controller). I will have this thing charging my car for all the right reasons, but one thing I REALLY would like to have is the feature that runs the car's squirl cage air circulation fan w/o having the key on, or the control switch clicked over.

Anybody have a good idea to help me wire that up? I've been clicking back and forth on different ideas on how best to set it up, but figured I'd ask you guys to see if you had any thoughts on the matter.

One of the best ways I could think of was this: Tap into the 12v output (to battery) directly to the fans + lead and have a large diode between the charge controller and the battery, so when the fan kicks on, it doesn't pull from the battery at all.

I realize this won't cause it to spin at warp speed as it will only be ~5amps of power, but if it's turning even on low speed, it's going to cool my car quite a bit.

To control the on/off of the fan, I have a few ways to do it. I do have an Arduino unit I could use to program and have the fan kick on only when the car hits X degrees. An easy way, perhaps temporary, is to have a relay activate when the key is off to enable the fan off the solar. The Charge Controller, unless mistaken, only puts out the 12v battery charge if it detects voltage on that end for a battery to be charged.

Anywho, throw me whatever ideas you might have to make this work. I'm still working on an acrylic sunroof and mounting everything up, so I'm not quite there yet... but I like to try and plan ahead.