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Electronics question

Quick question: Which is more powerful - 10 watts/24 volts or 12.6 watts/18 volt?


Jul. 27th, 2010 08:15 pm (UTC)
We're talking a solar-powered attic exhaust fan. From what I'm gathering the wattage is the solar panel and the volts are the fan motor, yes?
Jul. 27th, 2010 08:37 pm (UTC)
Watts are a measure of energy conversion, Volts are a measure of electromagnetic force. Basically what you're interested in is how many volts to produce how many watts.

In that regard, you're looking at 24v:10w vs. 18v:12.6w, or a 41.7% efficiency vs 70% efficiency. You'll get more "power" out of the first, but I'd go with the latter because its got a better conversion rate. Maybe get two (lol).

But then, I haven't studied Electrics (not Electronics) since Jr. High, so am consulting Wikipaedia for my information. I Am Not An Electrician.
Jul. 27th, 2010 08:50 pm (UTC)
As I said elsewhere, WHAT MAKE FAN GO MORE? :)
Jul. 27th, 2010 11:02 pm (UTC)
Wow, you guys are way off.

12.6 Watts is more power than 10 Watts.
You can sugercoat it any way you want, but power is measured in watts, so 12.6 > 10.

Watts = volts X amps

Nobody has mentioned how much current is flowing (amps), so trying to calculate efficiency is kinda futile without that.

Now if you're talking about power tools, generally higher voltage equals more torque.
Jul. 27th, 2010 11:55 pm (UTC)
I love my smrt friends. :)

So if 12.6 watts is more power generated by the solar panel, does it make a difference if the fan motor is 18 volts or 24 volts?
Jul. 28th, 2010 01:37 am (UTC)
What voltage is the solar panel putting out?

Often times you can overvolt a motor by up to 50%, so you can probably run an 18V fan on 24V without too much trouble, unless it's a brushless fan, in which case it has internal electronics and you should run it on the rated voltage.

If you put a fan rated at 24V on an 18V solar panel it will probably work, but not run as fast as it should, pushing less air around.

Also, look at the rated CFM for each fan (cubic feet per minute). That will tell you which fan will do a better job of cooling you off.

Edited at 2010-07-28 01:38 am (UTC)
Jul. 28th, 2010 01:45 am (UTC)
They're both rated the same, and the descriptions aren't clear about the solar panel output, only the fan motors. (I thought the 10 watt and 12.6 watt were for the solar panels, but now I'm not so sure). I think I might be missing some information, but if they're both rated about the same, I'm probably nitpicking over stuff that won't matter when it's hot anyway. :)
Jul. 28th, 2010 02:00 am (UTC)
If the fan rating is the same and they move the same amount of air, then look at other aspects to make your decision. I'd look at ruggedness if you're taking it to Pennsic, maybe price.

I'm guessing then that the fans come with the solar panels already? I thought you were trying to match up the right fan with a solar panel you had already or something :)
Jul. 28th, 2010 04:02 am (UTC)
I guess if they're rated the same then they probably go the same speed with their respective solar panels (yes, they come as sets). I was thinking maybe if one cleared that CSF faster than the other that would make it a faster fan, but I guess the rating must be # of CSF per some measurement of time, so they probably rotate at the same speed (and I was really, through all this, looking for the fastest rotation speed/airflow, 'cause I'm not using this as an attic fan, I'm using this as a personal fan).

Alas, the only reason I'm comparing is because the prices are exactly the same, so I figured I'd ask.

You're a peach for helping me think this out, though. Thank you!

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