Author Topic: Using 5V and 12V P.C. fans with FARS. (Read 16356 times)

DanS · « **on:** March 21, 2009, 10:00:46 PM »

I see where folks are using voltage step up circuits to be able to use small solar cells to power P.C. fans. Look here for ideas if you are trying this approach. www.instructables.com/id/The-Amazing-Solar-Powered-Fan-A-Green-Gadget/

I've personally haven't tried this so cannot verify if it works or not.

Dan

JOE · « **Reply #1 on:** March 22, 2009, 01:57:20 AM »

That was too long and difficult sounding for me to follow at the late hour (waiting on a big download), but I was wandering around in the local Walmart today and saw some of the solar landscaping light sets.
I think it was around $20US for a set of eight lights.

Just seems like there should be a simple way to connect all of them up somehow to produce enough to run a fan for a few hours after the sun goes down.

Put all the panels in one box with the batteries and run a wire to the fan. Might even help to position the panels in an arc shape to maybe "catch" a little more sunlight as the earth turns.

I'm still thinking about getting the Davis daytime FARS kit, but if I could come up with something for 20 bucks that would even run after sundown, I might try it.

DanS · « **Reply #2 on:** March 22, 2009, 03:07:44 AM »

Joe, if you want to run a fan even after the sun goes down then you will need to run the fan on batteries (or a powerpack and extension cord). I believe the current FARS discussion that's been going on here is with regard to running a fan when it's most needed, when the sun is shining on the shield. This way you can use the sun only for the power and batteries aren't needed. If I understand what you'e saying that you want the fan to run "for a few hours after the sun goes down" then you can do it with a small 3v fan and some rechargable AA batteries. The fan would run in the evening/night for as long as the batteries will support it. You could use a modified garden solar light to control the evening power on time. Check out this article for a car solar ventilator (especially step 3). You would do it a little differently for a FARS but the electronics are the same. www.instructables.com/id/%246-Solar-Fan/ basically you swap the solar light's L.E.D. for a 3v fan and that's it.
Hope this helps. Regards,
Dan

SlowModem · « **Reply #3 on:** March 22, 2009, 03:39:13 AM »

I came across this yesterday and thought it was interesting:

http://www.amazon.com/b/ref=amb_link_83808091_3?ie=UTF8&node=1253958011&

sam2004gp · « **Reply #4 on:** March 22, 2009, 08:13:49 AM »

Slow modem, I am sort of going that route.

http://www.wxforum.net/index.php?topic=3651.msg31229#new

mackbig · « **Reply #5 on:** March 22, 2009, 08:26:32 AM »

As cool as solar would be, from a cost perspective and maintenance its probably much easier to go low volt.... I know Sam has an issue with length of run, and going under a sidewalk.. but for many a cheap $20 low volt light kit will do the job, toss the lights, and using the entire cable lenght to get to your shield. 24/7 for pennies per month....

Andrew

Anthony · « **Reply #6 on:** March 22, 2009, 08:42:47 AM »

I've thought several times about using one of the solar battery chargers to run the fan in my FARS. But I've often wondered just how waterproof they are? I'd say not very waterproof since it is recommended that you place them on the dashboard of your vehicle.

The landscaping lights are a different. They wouuld be as long as you didn't alter the housing they are in. But considering they only put out about 3 volts. It would take a ton of them to run even a 5 volt computer fan.

sam2004gp · « **Reply #7 on:** March 22, 2009, 08:48:06 AM »

Quote from: mackbig on March 22, 2009, 08:26:32 AM

As cool as solar would be, from a cost perspective and maintenance its probably much easier to go low volt.... I know Sam has an issue with length of run, and going under a sidewalk.. but for many a cheap $20 low volt light kit will do the job, toss the lights, and using the entire cable lenght to get to your shield. 24/7 for pennies per month....

Andrew

A very valid point.

I have not ruled out the Low voltage light idea as of yet. Just exploring all possibilities. When I opened the package I made sure I did it, so I could take it back if needed.

DanS · « **Reply #8 on:** March 22, 2009, 07:15:19 PM »

Quote from: sam2004gp on March 22, 2009, 08:48:06 AM

Quote from: mackbig on March 22, 2009, 08:26:32 AM
As cool as solar would be, from a cost perspective and maintenance its probably much easier to go low volt.... I know Sam has an issue with length of run, and going under a sidewalk.. but for many a cheap $20 low volt light kit will do the job, toss the lights, and using the entire cable lenght to get to your shield. 24/7 for pennies per month....

Andrew

A very valid point.

I have not ruled out the Low voltage light idea as of yet. Just exploring all possibilities. When I opened the package I made sure I did it, so I could take it back if needed.

If you're going to go the hard wire vs. solar route you don't even need a low volt light kit. Get a wall power pack like a cable modem or router uses. Just read the spec's on it's back and make sure it has enough power to drive the fan you're using.

+

DanS · « **Reply #9 on:** March 22, 2009, 07:43:00 PM »

Quote from: Anthony on March 22, 2009, 08:42:47 AM

I've thought several times about using one of the solar battery chargers to run the fan in my FARS. But I've often wondered just how waterproof they are? I'd say not very waterproof since it is recommended that you place them on the dashboard of your vehicle.

The landscaping lights are a different. They wouuld be as long as you didn't alter the housing they are in. But considering they only put out about 3 volts. It would take a ton of them to run even a 5 volt computer fan.

Anthony, the panels that I've tinkered with have all been sealed in some kind of clear epoxy/phenolic type of compound, fixed to a circuit board. The plastic housing for yard type solar lights is cosmetic and not protecting the panel from rain. You do bring up an interesting idea for another project though, how many of the dollar store solar light panels would I need to run a 5v fan..... hmmm, next project. I'm guessing 2 would do it.

DanS · « **Reply #10 on:** March 22, 2009, 10:46:59 PM »

Quote from: brucifer on March 22, 2009, 09:42:08 PM

As much as I like to tinker and take on small hobby projects, I think I'm going to go with a Davis VP2 FARS (07747) sometime in May and be done with the fan issue. I imagine that a daytime fan will be enough to keep the temp readings honest. Question: Once I make the upgrade, will I have an extra SIM panel left over? From the picture, it looks as if I will.

Bruce

It appears that both of those panels are used together to power the fan.

Anthony · « **Reply #11 on:** March 23, 2009, 07:43:40 AM »

Dan, I don't think 2 alone would do it. Sure they would give you enough voltage. But I don't think they would provide enough current. Would probably need 4, 2 sets of 2 in series and then the 2 sets in parallel.

SlowModem · « **Reply #12 on:** March 23, 2009, 08:15:31 AM »

Quote from: Anthony on March 23, 2009, 07:43:40 AM

Dan, I don't think 2 alone would do it. Sure they would give you enough voltage. But I don't think they would provide enough current. Would probably need 4, 2 sets of 2 in series and then the 2 sets in parallel.

The way I understand it, each cell is like a 1.5V battery. Try your calculations like that.

DanS · « **Reply #13 on:** March 23, 2009, 08:46:20 AM »

Probably right with the current being insufficient. The solar lamp that my panel came out of was designed to recharge 2 rechargable batteries (2.4v total) and I measured the output voltage of it under load of the fan in full sunlight at 3.2v.

Anthony · « **Reply #14 on:** March 23, 2009, 02:40:13 PM »

Dan, Alright, we know they cells you have put out 3.2v in full sun. Now the question is. How much current? Does the meter you are using to measure voltage also measure current?

sam2004gp · « **Reply #15 on:** March 23, 2009, 03:03:07 PM »

Current or Amps is very important. I am running 17 or 18 volts on my panel, and I am getting currents up to .07 when the fan is in operation. Not full power for the fan, but sufficient to move the air for the purpose at hand.

DanS · « **Reply #16 on:** March 23, 2009, 05:58:56 PM »

Quote from: Anthony on March 23, 2009, 02:40:13 PM

Dan, Alright, we know they cells you have put out 3.2v in full sun. Now the question is. How much current? Does the meter you are using to measure voltage also measure current?

I'm going to check that again today since it's supposed to sunny and clear. I did a quick ohm measurement on the fan motor and measured 9.5 ohms. Using this figure and the 3.2v panel figure and I=e/r I got .33 amps which I don't believe so I'll do a more detailed check today. I'll also put a meter inline for a current check as well.

DanS · « **Reply #17 on:** March 24, 2009, 12:27:53 AM »

Quote from: DanS on March 23, 2009, 05:58:56 PM

Quote from: Anthony on March 23, 2009, 02:40:13 PM
Dan, Alright, we know they cells you have put out 3.2v in full sun. Now the question is. How much current? Does the meter you are using to measure voltage also measure current?

I'm going to check that again today since it's supposed to sunny and clear. I did a quick ohm measurement on the fan motor and measured 9.3 ohms. Using this figure and the 3.2v panel figure and I=e/r I got .33 amps which I don't believe so I'll do a more detailed check today. I'll also put a meter inline for a current check as well.

Anthony, today I desoldered one lead from the panel for measurements and got pretty much the same readings as before. Today is a little hazy so full sun is not like it was the other day. I got 3.0V from the panel (under load, 6.1v unloaded). Fan motor reads 9.1 ohms resistance. A meter inline for current measurement showed just over 300ma. That's the number I have difficulty with but the math confirms it too.

sam2004gp · « **Reply #18 on:** March 24, 2009, 07:21:17 AM »

Dan, I found a couple 12 Volt fans at .3 amps, they did not work well. I was lucky enough to find one in junk drawer that was at .11 amps and it works pretty good. Voltages are always there, but without the current, it's a no go. Oddly enough I have not found many 5 Volt fans around.

DanS · « **Reply #19 on:** March 24, 2009, 07:40:25 AM »

Quote from: sam2004gp on March 24, 2009, 07:21:17 AM

Dan, I found a couple 12 Volt fans at .3 amps, they did not work well. I was lucky enough to find one in junk drawer that was at .11 amps and it works pretty good. Voltages are always there, but without the current, it's a no go. Oddly enough I have not found many 5 Volt fans around.

Yeah the lowest amperage 12v fans will work the best with that panel. If you do find and try a 5v fan you will have to put a limiting device (power resistor, voltage regulator, etc.) inline because under full sun it would probably burn out (after your FARS lifts off

). You mentioned earlier that you got the .11amp fan to come on in the early morning sun? If so that sounds like a good setup/match. Aren't tinkering type projects fun?

Cheers, Dan

sam2004gp · « **Reply #20 on:** March 24, 2009, 07:52:17 AM »

Yeah a blast,...... it's modifying/hacking my current shield that makes me hesitant. Oh well. Got to do it sometimes. Besides it ain't nothing but plastic and some more money.

DanS · « **Reply #21 on:** March 24, 2009, 07:58:14 AM »

Would it be possible to just buy a couple more white plastic bowls that match pretty close and remove only the top existing one. That way you butcher only the new ones and don't change any existing ones and anything gows wrong you can go back to original config.? make sense?

Anthony · « **Reply #22 on:** March 24, 2009, 08:06:42 AM »

Well for me the FARS is built & fan installed. All I need is a solar power source for the fan. I think the fan requires 650ma. Which is quiet a bit to expect from a solar pannel. Since I am planning on doing the heater mod to my rain guage. I may just bury a power cable and forget about it.

DanS · « **Reply #23 on:** March 24, 2009, 08:09:50 AM »

yeah 650ma is quite a bit to drive. The power run sounds like a good way to wrap up that job. By chance did you take any pics? Love to see the art work from your efforts.

Anthony · « **Reply #24 on:** March 24, 2009, 08:14:44 AM »

The FARS that I am using was not designed or built by me. Another member of this forum dontated me his old OS WMR-968 weather station when he upgraded to a Davis. He was very generous and threw in the FARS.

In the past I have simply drug an extension cord from the house to the weather station. But it becomes a pain to roll it up every week when I mow the grass.

NOTE: Edited for typo.

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Author Topic: Using 5V and 12V P.C. fans with FARS. (Read 16356 times)