Wiring a fan (or other electronic)

Jedi Bob

Well-Known Hunter
I am trying to wire a 12V fan in my helmet and am concerned because the 9V is getting really warm and I am afraid of it blowing in my helmet. (I HAVE had a 9V pop on me!)

How should it be wired?
The battery is what is getting hot. Not in the helmet. I was thinking that even in the "off" position, current is stiull running through and causing the battery to heat up.
He said the battery stayed cool, if you hook up another fan to it the battery wont pull so many ohms. One 9volt battery in a 12 volt fan is making it overheat, just get another fan.
I got it. I was just trying to use this fan cause I got it for free. ;)
I have spent so much $$$ on this outfit that I am trying to save anywhere I can.

Thanks :)
I would think so.

As I mentioned earlier, I had a 9V pop once.
Would it being too weak cause that to happen?

maybe I'll just sweat it out. :lol:

cal196 wrote:

hehe I think a couple more bucks is worth not getting battery acid all over your face.

Thats how Boba's Voice changed from the clone AOTC to the way it sounds in the Empire strikes Back. LOL :D haha!
We are are required to wear our helmets at all times. I use a nitrogen-mesh cooling matrix that is integrated to my climate control body mesh for use in adverse weather/temperature situations. My asbestos lining causes my suit to be quite warm, especially when I am using my flamethrower. And I am prone to being warm due to my weight problem.

FettTheHunter wrote:

You guys have fans in your helmets !!!... does it really get that hot after a while :eek:
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Darn...and I've only got a adapted Grey Boiler suit and a non working flame thrower :D

I shall have to look into installing a fan when I get my Don post then :)


Jedi-Bob wrote:

The battery is what is getting hot. Not in the helmet. I was thinking that even in the "off" position, current is stiull running through and causing the battery to heat up.

If what you're saying is true, that the batery is getting hot in the "OFF" position, then the problem is that you wired the switch incorreectly (and believe me, this is a common mistake among those who are wiring in fans).

Check to see how you wired it. You only want the switch in series with ONE of the power wires. If both your positive and negative wires go through your switch, then the problem is that you are shorting the battery when you turn the fan OFF.

If this sounds like what's happening and you need more clarification, let me know. :)

Here's one way you could do it


This configuration places the fans in parallel with an LED to lower the voltage. I used this in my TIE bucket and it worked great.
That set-up may work great for a while, but will GREATLY reduce the lifespan of the LEDs. There needs to be a current limiting resistor in series with the LED to keep it from burning itself up.

Out of curiosity though, what's the rating (forward voltage) of the LED? I know a 12V fan will run at 9V and slightly under, but am curious what kind of voltage they're seeing due to the LED.


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