Mod HVAC fans to run on solar power while car is parked?

[Throckmorton]

Obviously solar panels are for sissy Prius owners. The real solution is to use thermoelectric generators.

In all seriousness, a thermoelectric generator allows you to power a small fan or two without needing a solar cell on the outside of your car or in the window, or require you to remember to setup something.

If I were going to do this I would install fans/vents inside the door cards, possibly blowing through the speaker covers if that was possible. One would draw air in through the door drain vents, the other would expel it out the other side of the car through the door drain vents also. A control relay connected to the power window system would turn it off when the vehicle's electrical system was on. I wouldn't bother with a battery at all. Maybe a biggish capacitor, but that's a big maybe. I like thermoelectric generators for this because they are powered directly off of what you're trying to avoid: a temperature difference between outside and inside the car.

That's what I would do, as an engineer.

I really think a thermoelectric generator would be a bad idea. You're talking about a "peltier" in reverse right? Well the problem is that it depends on temperature differential between the body shell of the car and the interior of the door, or wherever you put it. So on a light colored car it won't be as effective. But more important, if temperature rises gradually it won't do anything. Then once the interior and exterior are both hot, when you need a fan the most, it won't work. It's a feedback that runs counter to what you want

 

[Imported]

Just wanted to jump in and say I have this feature on my Prius and its been awesome the past week with the 100 degree temps we've been experiencing. I can't help you with the behind the scenes stuff on how it works, but if you need a specific photo or two to help, let me know.

 

[rsutoratosu]

this fving sucks, i dont know why they put that vent/ac option on a prius and not on the lexus hybrids

 

[exdeath]

:thumbsup: That was going to be my recommendation as well. Much easier to implement and it will also help protect your paint.

Car cover on and off a dirty car every day will do more harm to the paint than good.

 

[natto fire]

You can't really put a car cover on when you're parked at work or at a park & ride station. And if you do it at your apartments, you look like that dbag obsessed with his car. Not to mention the time it takes. You aren't going to put a cover on so you can go in a shop for an hour.

A fan works and is simple-- at most you'd just have to flip a switch. I think all cars need to just come with a system like what the Prius has, except it doesn't need to be so complex.

As I already posted earlier, and other posts have said, it is not as simple as you think it is. Just because something seems simple in theory does not mean it is effective in practice. The system on the Prius is complex because I am assuming it is effective. If you want a gimmick, then order one of those joke window vent fans.

I already posted the fundamental logic of why this is harder than it seems. I have done countless wiring jobs on cars for various reasons, and am not trying to cut you down but just trying to explain the basic problems with your ideas. If between posts here explaining these problems, and a major car manufacturer's hurdles, you still aren't grasping the concept, then you are just being stubborn.

Aren't you the poster that has an all-out grudge against any rear suspension which is not independent?

 

[Throckmorton]

If sunshades look trashy you should get your priorities in line. Shades are worth every penny. If you want something that's custom fit, try this: http://www.covercraft.com/uvs100.html

See, the picture shows it in a vette. High class.....

I was talking about the shades that go in the windows. Customizing your car with stuff from Autozone is trashy.

 

[Throckmorton]

As I already posted earlier, and other posts have said, it is not as simple as you think it is. Just because something seems simple in theory does not mean it is effective in practice. The system on the Prius is complex because I am assuming it is effective. If you want a gimmick, then order one of those joke window vent fans.

I already posted the fundamental logic of why this is harder than it seems. I have done countless wiring jobs on cars for various reasons, and am not trying to cut you down but just trying to explain the basic problems with your ideas. If between posts here explaining these problems, and a major car manufacturer's hurdles, you still aren't grasping the concept, then you are just being stubborn.

Aren't you the poster that has an all-out grudge against any rear suspension which is not independent?

I don't have an "all out grudge against any rear suspension which is not independent". I have a grudge against idiots on this forum who believe that a solid axle can be "well engineered" enough to be "just as good as independent". I own a Mustang and I can say definitively that the solid axle has significant problems on rough pavement. Accelerate while hitting a ridge or something and it feels like the rear is going to rattle apart as the wheels hop around. Anyway, back to the topic at hand...

Sorry, I didn't see your post about the amps needed for a blower motor. You're the ONLY person who said that. Other people were just posting nonsense about needing batteries "because it's more efficient"-- as if efficiency matters with free power. Your post with the actual amperage needed is actually helpful, because the amperage you gave is orders of magnitude less than a small panel can generate.

So it seems the best way to flow air through a car is with a low amp blower motor and a solar panel.... as in bigger than those cheesy ones that go in a window (which those of us with coupes can't use anyway). But you have to find a vent for the blower.

 

[LTC8K6]

Solar Ventilation System
The solar ventilation system uses energy provided by a solar panel built into the roof to operate the blower fan contained within the air conditioning system. This allows ventilation of the vehicle interior when the vehicle is parked in direct sunlight.
The solar panel is located on the roof above the rear passenger space, as shown in the illustration. It consists of 36 poly crystalline silicon solar cells connected in series, and is primarily constructed from glass, potting material, silicon, silver and aluminum compounds, and a back sheet.
The solar panel generates a nominal 60 Watts of electricity, and although the voltage and current output vary by temperature and sunlight intensity, the panel does not produce high voltage. For example, the solar panel output is 22 Volts on an average sunny day (77oF, 25oC) and has a maximum output of 27 Volts in sub zero temperatures (-22oF, -30oC). The maximum current of 3.6 Amps occurs at full sunlight intensity.

http://www.youtube.com/watch?v=CchHIy7JgvA

It is operating the same blower fan that the HVAC system uses, but Toyota has a very good solar panel.

The blower doesn't start immediately, it's on some kind of timer or temp control system. It doesn't operate while the interior is still cool from running the A/C, for example. It doesn't waste the cool air that remains in the cabin. It doesn't run continuously either, apparently. Only when it needs to.

 

[gorb]

I'm also in TX and getting a heatshield shade has really helped. It's still hot in the car, but it's a hell of a lot hotter when I don't use the shade. I'm actually thinking about buying the side window shades as well.

 

[natto fire]

I don't have an "all out grudge against any rear suspension which is not independent". I have a grudge against idiots on this forum who believe that a solid axle can be "well engineered" enough to be "just as good as independent". I own a Mustang and I can say definitively that the solid axle has significant problems on rough pavement. Accelerate while hitting a ridge or something and it feels like the rear is going to rattle apart as the wheels hop around. Anyway, back to the topic at hand...

Sorry, I didn't see your post about the amps needed for a blower motor. You're the ONLY person who said that. Other people were just posting nonsense about needing batteries "because it's more efficient"-- as if efficiency matters with free power. Your post with the actual amperage needed is actually helpful, because the amperage you gave is orders of magnitude less than a small panel can generate.

So it seems the best way to flow air through a car is with a low amp blower motor and a solar panel.... as in bigger than those cheesy ones that go in a window (which those of us with coupes can't use anyway). But you have to find a vent for the blower.

No worries on missing my post, I am a skimmer of threads myself, unless I created them, that is. I think the reason those "gimmick" products don't work is because they seem to be using a simple 120mm fan or small squirrel cage blower. Great for lowering power draw, reducing panel size, bad for moving large volumes of air. Solar panels are unfortunately not at an energy density level for widespread automotive use, IMO. They are improving quite a bit to where you can cover your entire south facing roof with them and merely supplement the energy needs of a standard 4-5 person household.

The advantage of the "gimmick" products is that they do vent the air outside, which is again another piece of the puzzle besides providing the power for the blower to spin. It wasn't explained in detail on the great post above about the Prius system, but I would guess there is either a dedicated exhaust pathway the blower switches to, or it spins in reverse to exhaust through the fresh air intake on the cowl. The second setup is not as likely if using a squirrel cage blower as the blades are not designed for reverse operation.

Re: rear suspensions. I will agree that it is nearly impossible to make an axle behave the same as freely sprung halfshafts (or drift hubs for you FWD folk) but there are also advantages to a live axle over independent in many situations. Bottom line: in the extreme fringes of a vehicle segment where few, if any, compromises are made for cost cutting you will find that a live axle has it's place, and I agree trying to keep the tires of a sports car to the ground is not one of those.

 

[marvdmartian]

Here you go, get a couple of these, and stick 'em in your windows when you park.