Solar Truck Vent

[tperk]

I am a newbie to solar.

I am planning to install two computer case type fans just barely inside (so that I can still open and close window) of the rear sliding window of my truck. The purpose is to keep inside temp down so that my dash cam stops failing and to simply have a lower and more tolerable cab temp after parking in the sun. I am trying to determine:

- how to set up and run fans off of thermostat set to about 85 degrees.
- how to power the fans. My truck is diesel and has two in parallel batteries. I wonder if I can get by without a solar panel. The truck typically sits in the sun without being started up for a week at a time.
- OR I could power fans from truck and use a solar charger to keep the truck batteries charged.....if needed.
- OR I could use a separate smaller battery with a solar charger.
- I imagine the 12v fans would draw less than 1 amp each, probably a max of about 2 amp combined.

Before I go about this in my typical "try things until they work" modus operandi, I would appreciate some suggestions on how to do this correctly.

Thanks much

[soleram]

I am not sure what you mean by "computer case type fans", if these are 12v. fan for a desktop or computer tower, that may be too small.
For my truck, I have a 12v fan https://goo.gl/Prn7BZ small and powerful enough , and just plugged-in the 12v. socket.
Works well.

[J.P.M.]

I'd start by getting the camera off the dash and out of direct sunlight.

[tperk]

What's the point in having a dash cam if it needs to be removed every time I park in the heat?

I am open to using any fan or combo that will work for me. Soleram, Manufacturer says that your fan draws max of 3 amps. As I stated above, I need to let it run sometimes a week at a time. What do you think that will do to my batteries? I believe a need a renewable power source which is why I came to this forum. Also I need to thermostatically control the on /off so that current draw is minimized.

[SunEagle]

What's the point in having a dash cam if it needs to be removed every time I park in the heat?

I am open to using any fan or combo that will work for me. Soleram, Manufacturer says that your fan draws max of 3 amps. As I stated above, I need to let it run sometimes a week at a time. What do you think that will do to my batteries? I believe a need a renewable power source which is why I came to this forum. Also I need to thermostatically control the on /off so that current draw is minimized.

First determine the voltage and wattage requirements of those fans. 3 amps is pretty high but at what voltage? Some computer fans use 5v others use higher voltages.

Then look for some type in line thermostat that can handle the starting of the fans.

Once you have that information you can size a small AGM type battery to run the fans and the solar panel wattage & charge controller needed to keep that battery charged.

[bcroe]

You need to see what energy would be required. 3A half days for a week comes to 3A X 12 hour X 7 = 252 amp hours, which
I am quite sure is enough to flatten your battery. RVs use a separate battery charged through an isolator by your alternator,
then you don't have to worry about the start battery. A solar system capable of supplying this energy will probably be
substantial enough to make you reconsider moving the camera. good luck, Bruce Roe

[tperk]

Let's assume 3 amp @ 12v or 36 Watts as the maximum I will use. Let's assume the fan runs a maximum of 12 hours per day. Can you tell me what size battery, and what solar system I would need?

Thanks much.

[Mike90250]

I'd look at using a dashboard 10W PV panel and run a fan directly off it. No sun = no fan

[tperk]

Mike.......Nah..I don't want to do that. I intend to mount the panel on the roof of my truck. No sun = no fan is probably OK with me since it seems a lot simpler. You suggested a 10 Watt panel. I know NOTHING about this stuff. How would a 10 Watt panel run a 2 amp 12v fan?

Generally, what happens if a panel is not producing enough electricity for the load?

[Mike90250]

i'm thinking low power, a couple 12V DC brushless computer fans Different models have auto restart feature, and will try to restart when solar power is too low. Nowhere near 2A draw for 2 of them

[SunEagle]

Let's assume 3 amp @ 12v or 36 Watts as the maximum I will use. Let's assume the fan runs a maximum of 12 hours per day. Can you tell me what size battery, and what solar system I would need?

Thanks much.

If each fan draws 36watts and you plan on using them for 12hours that calculates to 432wh x 2 = 864wh.

If you use that much power a day you will need a battery that is approximately (864wh / 12v x 4 = 288Ah). That will require solar panel wattage with charging amps around 29 amps with an MPPT type charge controller (29a x 12v = 348watts).

You can probably get away with a 12v 232Ah system (2 x 6v 232Ah) batteries and say 300 watts of panels along with a 30Am MPPT charge controller. That system is going to run you at least $1000.

Or you can use a smaller panel (10w to 15w) as Mike suggested and hook it directly up to the fans and let them run when the sun is out. You don't need a lot of air movement so you need just enough panel wattage to spin the fans at some middle speed when you need it.

Although I am not sure if a couple of computer fans will help do the trick but I guess they will keep your dash camera cooler.

[Mike90250]

in the 90's I had a "Window Vent Fan" that attached to a roll up window, and had a 3x3 solar panel and it sucked air from the headliner area, and vented it outside. Not a lot of air, and it had a rain shroud to keep the car dry.
A search at Amazon for "solar powered car window fan" brings up a couple hits. one on driver & pass doors should help

[Logan5]

What's the point in having a dash cam if it needs to be removed every time I park in the heat?

I am open to using any fan or combo that will work for me. Soleram, Manufacturer says that your fan draws max of 3 amps. As I stated above, I need to let it run sometimes a week at a time. What do you think that will do to my batteries? I believe a need a renewable power source which is why I came to this forum. Also I need to thermostatically control the on /off so that current draw is minimized.

get a better dash cam. not sure why a quality dash cam would fail under normal dash operating temperatures. I have had good luck with DC motor fan's connected directly to a 17v solar panel. the more sun, the faster it blows, However if it gets stuck, it could burn out the motor, so selecting the correct fan motor is key. you could also consider using a sacrificial SLA battery as a buffer and set a high LVD to buffer the panel to motor connection. probably better to get a better dash cam. do not connect this fan to your CCA battery.

[J.P.M.]

What's the point in having a dash cam if it needs to be removed every time I park in the heat?

I am open to using any fan or combo that will work for me. Soleram, Manufacturer says that your fan draws max of 3 amps. As I stated above, I need to let it run sometimes a week at a time. What do you think that will do to my batteries? I believe a need a renewable power source which is why I came to this forum. Also I need to thermostatically control the on /off so that current draw is minimized.

You don't need to remove it. Simply mount it out of the sun (shade it a bit) and away from the dash. It'll stay cooler. You may still need some vent cooling but the camera will stay cooler, the heat load will be less and keeping the camera cool will be easier to manage.

[tperk]

Guys,

Thanks for all your help. Dash cam heat tolerance is another subject, and very lengthy. Am going to buy panel and fan/s....PERIOD. Heading out now for 10 day vacation.

Thanks again!
Tom