This is a post I created on another forum to discuss effective ways of keeping your vehicle's interior cool while having to leave it parked in the direct sunlight for long hours.

My question to you guys is concerning the ventilation system in the 1999 - 2005 model Grand Vitara's. If I were to install a small solar powered 12V 'expel air' type fan in the vehicle, are there any factory vents that would allow fresh air back into the vehicle? If so, where are the located?

Thanks

This was the original thread btw..

Anyone ever come across any decent products you can use to keep the interior of your vehicle cool, when you are forced to leave it parked outside in the sun for a long time?

Our car park at work has no shaded areas and I really hate leaving it out to bake for such long hours in the direct sunlight. In the long run, that will take its toll on the interior..

I am looking for something preferable solar powered and properly designed to ventilate the interior. It should also be designed in such a way that no (rain) water or dust can easily get in.

If you are aware of any products that can do this, or if you come across any while browsing, please post them here..

The GV has vents around the rear quarter windows and also under the rear bumpers (most cars have them here), you can also set the a/c system to vent which will open a flap to the air intake at the base of the windscreen.

I put window visors on mine so I can leave the windows down an inch or so without the possibility of water getting in if it rains - and this reduces the heat build up quite noticeably.

You might want to do a google search on those solar powered vents fans though - I have a recollection of someone doing a series of tests and concluding that they're not very effective - it seems the fans and solar panels are too small to move a significant volume of air.  I must point out though - I don't recall his location, so the amount of solar energy may not be as intense as it is in Trinidad.

A couple of decades back I worked for a company that sold solar powered marine navigational aids and we were having problems with a couple of the units we had installed in Guyana - my disgnosis was "over charging" so I took it up with the manufacturers and was told it wasn't possible as the units were sef regulating - I faxed them my voltage readings, etc., and two weeks later the vice president in charge of tech support called me to say he was sending charge regulators, my response was I had already installed charge regulators and had not had a repeat of the problem since.

He shared with me that they had installations all over the world, including desert areas such as the Suez canal and had only experienced over charging in two locations - Guyana & Trinidad - so apparently our proximity to the equator can have both advantages & disadvantages.

Now that you mentioned it, the window visors do seem like the most cost effective solution..

Most of the 'as seen on tv' products advertised to do solar powered ventilation are poorly made and not that effective at getting the job done..

To do this right, I was looking at a 5W 12V Solar Panel with regulator.. (Higher powered panels are available)

http://www.amazon.com/Instapark%AE-Mono-crystalline-Solar-Charge-Controller/dp/B004FOEUI0/ref=sr_1_1?s=automotive&ie=UTF8&qid=1314851148&sr=1-1&tag=vglnk-c605-20

http://www.instapark.com/solar-panel-solar-powered-products/5w-mono-crystalline-solar-panel-with-12v-charger-controller.html

Small 12V rechargeable battery

http://www.amazon.com/Volt-Rechargeable-Battery-187-Terminals/dp/B002QGVWBW/ref=pd_sim_ol_4

and some 4" or 6" energy efficient 12V cooling fans.

The fans can be placed under the front seat(s) and vented to the outside via ducting. (I haven't figured out all the details as yet..)

It would have been ideal if I could have eliminated the battery though. Can a 12V fan be powered directly off a solar panel?

Reason for asking is that the specs on the Instapark panels quote the maximum voltage as (Vpm) as 17.5V.

I don't know what Vpm stands for.. and 17.5V might be noo much for most 12V fans.

Also, if the solar panel has a 'charge controller', shouldn't the output voltage be limited to ~14VDC to prevent overcharging of the batteries??

One of these thermostatically controlled switches could keep the entire system automatic..

http://www.amazon.com/Senasys-120%C2%B0F-Fan-Style-Snap-Disc-Switch/dp/B0026RTEZC/ref=pd_bxgy_hi_text_c

The "as-seen-on-TV" style don't use a battery, they run the fan direct from the panel, but this has certain, perhaps undesireable side effects - it takes more power to start a motor turning than it does to keep it running, so you would often see situations where you have good sunshine and the fan isn't running.

Have you considered where/how you'll mount that panel, keeping it safe from interfering fingers?  If I put that on my vehicle & park in Georgetown there's a good chance it would not be there on my return.

Regarding the output voltage - solar or photovoltaic panels are a relatively high impedance power source - unlike batteries or generators - they are not constant voltage but constant current and output maximum voltage at minimum current, maximum current into a dead short, and maximum output (in terms of watts) at some point in between - if used to charge a battery (perhaps the most common use), the voltage measured at the panel output will be the battery's terminal voltage, and the current whatever the panel can deliver at that voltage, based on how intense the sunlight striking the panel is.

Charge control or regulation is typically done by disconnecting the panel from the battery (using a relay) to prevent over charge, rather than regulating the voltage to a fixed 13.8V, as the relay method is more efficient (more energy stored into the battery, less energy dissipated as heat).  More sophisticated charge controllers use both techniques, switching from constant current mode/relay type control to constant voltage after the battery reached 90% full charge.

We used a device called a Linear Current Booster or LCB from Bobier Electronics to "impedance match" motor loads to PV panels if we weren't using batteries - mostly for solar powered water pump installations, again for effiency reasons, we stored water in overhead tanks, rather than electric energy in battery banks.

Tinted the windows i my GV helps and a sun shade on the front helped.

Tint usually helps, however, for some of us - it's not an option - not unless you like being pulled over & hassled by the police.

Fines for illegal tint (defined as any shade dark enough to obstruct clear view of the vehicle's interior) went up to $2000TTD or $311USD! So I can't take any chances with that..

I understand what you say about charge control vs voltage regulation. If this were to work, efficiency would be a key factor because of how small scale the project is.

I can safely roof mount the solar panel since my vehicle is rarely left out in public. I also have a lot of audio equipment inside the vehicle, so the solar panel is the last thing I would worry about being stolen.

What I haven't fully figured out yet is a nice safe location to vent the hot air outside, other than through the windows..

There are limits here to. But nice to have some tinting.

Fines for illegal tint (defined as any shade dark enough to obstruct clear view of the vehicle's interior) went up to $2000TTD or $311USD! So I can't take any chances with that..

Guyana law provides a number - 33% - the tint must not prevent more than 33% of the light passing through the window - however in true Guyanese style, the "tintometer" used to determine the level of tint uses a process that works in the reverse of the wording used in the law, and, typically none of the officers who stop you will have one, so you end up going down to the station and wasting a half day or so in the process.

It's easier to just not have tint & don't get pulled over.

I'm curious as to how I will fare with this - I was one of the very early adopters of tint films, before there were any laws governing the use of tint, and escaped being pulled in during many a tint campaign because I used a reflective mirror tint rather than a dark one, but eventually the police learned about the existence of sunch films and I got rid of that vehicle - but earlier this year I acquired a Mitsubishi Pajero iO - which comes from the factory with what is termed caribbean tint - a medium dark tint around the rear "three quarters" of the vehicle - everything but the two front doors & the windscreen.  The vehicle has been in the country for almost five years, and as far as I know has never been pulled over for tint, so I guess I'll wait & see.

3M supposedly makes a clear tint film that cuts IR transmissions by almost 90% that would be ideal in situations like this, but I understand it's quite expensive and not sold to the public but only through installers.

http://solutions.3m.com/wps/portal/3M/en_US/Window_Film/Solutions/Markets-Products/Automotive/Crystalline_Automotive_Films/

I use the Llumar UV shield on my windshield..

http://www.llumar.com/en/AutoUltravioletProtection.aspx

and their 30% tint on the four doors. The rear window and quarters have a much darker 20% tint..

Even with that, the interior gets uncomfortably hot when parked in direct sunlight.

I have both the forced cooling idea and the windshield reflective shields to try..