Electrical question/cosplay

DMS General
#1

Hello,
The issue is I am running 4, 12v fans in a cosplay helmet, I know very little to knowing about power and current, I used a 12v power supply, but having 4, fans made them barley work, I realized that the powere supply wasn’t powerful enough to sustain them, I also have 4, 5v fans to try, but need assistance, I have space requirements, and I’m open to suggestions. I hand wired all of it, and it worked shortly,

I need to increase the fan speed, and lifetime of the battries. I will be trying my hand at Soldering for a better connection. Any one if you could help that would be greatful.

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#2

You probably need more amperage.

This is a better question for @artg_dms or @Raymond.

Battery pack configurations are an art form. The good news is we have a spot welder in Electronics to fabricate the optimum power pack. Or go to Tanner’s and buy the plastic thingies. (Tanner’s might be better for ease of recharging.)

Then all you have to do is figure out how to charge it. Another bit of fun.

#3

A sketch of the circuit would help. Is it powering the lights as well?

#4

You do not indicate how the fans were wired. If they are in series, one after another, each fan is only getting one fourth of the voltage, 3 volts, so they are naturally going to run slower.

If you wired them in parallel, the four beside each other, each fan will get 12 volts, but the power supply or battery may not be able to provide four times the current as a single one. The voltage at the terminals will sag and again, the fans run slowly, but not as slowly as the fans in series.

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#5

For LEDs you use the voltage and the resistor sizes to figure out the current draw… and the fans will have current listed on them. From there you’ll have to calculate what size batteries you’ll need to last the time period you want. Size, shape, charge type, etc… will all get taken into consideration.

Oh, and if you’re using 5v fans from a 9v or 12v power source then you’ll need something to drop the voltage. I’d recommend something in a switching regulator and not a linear since linear regulators dissipate a lot of heat.

2 Likes
#6

I linked the first two together, and then the second two as a pair, then ran them into an on/off switch which led to the power supply

#7

Raymond, do you have a link to what these are so I can read about them?. Also wouldn’t 4, 5v fans draw more, or would the resisters compensate for that, and run them smoothly,

#8

Mathewbusby,

No the led are on their own powersupply and work perfectly, I don’t have a diagram, but I wired two pair of fans together, and ran them through and on/off switch.

#9

You can also grab the USB to Case fan cables. (Fry’s has them, just look in the computer parts area.) Then use a USB battery for them.

I have used this setup on the train in a sleeper car before for added ventilation.

#10

The crux here is how you wired them. Series or parallel. No one can help without that info.

#11

We also need to know what your power source is… and what the current capacity of it is.

For example: 9v square batteries output around 58ma/hr (depending on type, of course…) but AA, C, and D batteries have a lot more current capacity, but take up a lot more space. If you’re using lithium rechargeables then there are considerations to make around heat generation and avoiding complete draining of the battery.

1 Like
#12

Wow! What a cool helmet.

There are a few electronics types around that can help with that. I am around some, can help as well. I am at space today and Thursday as well.

Here are some DC relationships that help for solid, steady voltages and currents:

V=ir
P=iv

Voltage v, current i, resistance r, power p.

It gets more complex with ac because now the waveforms of the voltages and currents are sinusoids. Nevertheless, for lumped (u r lumped if ac is being used in this application) then the same equations hold true at any instant in time. So power will be the average over the whole sinusoidal cycle, so there is a trick to this, if needed.

Poll just DC tho, in which case u can check one fans power consumption by powering it with supply from elab that shows current used. P=iv so take supplied voltage, mult by current and u know how much power used by one. Now how much power is supply rated to deliver?

Feel free to grab me to show off helmet, or help if needed…

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