Helmet Fan Setup: What am I doing wrong?

[GotWookiee]

I'm wiring up 3 helmet fans into my Chewie underskull. Two 12VDC 40mm fans will serve as exhaust fans on the front and back back of my forehead. A 25mm 12VDC fan will draw air in through the nose. Three 9V batteries (mounted on top of my head in the underskull) will connect to a simple two position switch with two posts for wires.

Now, my level of understanding of electronics is on the level of "if the smoke gets out of the wire, the wire is no good and needs new smoke," so bear with me.

I found a few tutorials and some posts here on the RPF, including one with a similar setup to mine. However, I cannot seem to get multiple fans and batteries to work on the same circuit. A single battery with a single fan (switch or not) will work, but no such luck when two fans and two batteries or three fans and three batteries are hooked up.

Here is the simple circuit that works:

Here is the one I am trying to make work:

 

[j0wE]

i think you just dont have enough power going to them. 12X3 = 36 and 9X3 = 27, you're missing another 9V battery

 

[Psicorp7]

I agree with j0wE.....MORE POWER!!!
Power Good. Make fans go. Keep Wookie from passing out. Passing out bad.

You can also use my "go to" battery for helmet fans, the A23 12volt remote battery. They are about 1/2 the size of a AAA battery and deliver 12volt power. They only last about one troop but they are very light, fit in helmets well and two packs sell for about $4.00. You can get them cheaper in bulk on eBay.

You would only need three tiny A23 (one for each fan). Much lighter than 9volt IMHO.

Good Luck!

 

[j0wE]

I agree with Psi

 

[James Kenobi 1138]

I switched my helmet fans in 2 helmets from 9volt to AA set-ups.

The 9volts gave lots of power and were small and light, but after 2-3 hours they ran dead. And after the first hour the fan started running slower and slower.

To test the AA set-up, I installed fresh batteries at bedtime, turned on the fan and in the morning the fan was still going.

Maybe you'll have better luck then I did. Maybe get it all going one evening on the kitchen counter and see how much time you've got on your fans.

 

[GotWookiee]

I messed around with this stuff until I got this working setup:

If at first you don't succeed. Try, try, try, try, try, try, try again.

James, with your setup, how many AA batteries are you using?

 

[longlenium]

y dont you try the run the fan in parallel and keep the battery in series . so you will have 27v and even amp all around

 

[James Kenobi 1138]

I'm using 8 per fan, but I've only got 1 fan in each helmet so it's not really heavy or bulky. They are split up in 2 packs of 4 batteries each.