helmet with a fan

[lurkingknight]

So I am going to build a forced air vent system for my new opscore helmet.

I have a 5x5x2 cm blower fan that I will hang in a counterweight pouch on the back of the helmet with a battery pack and I will pipe the blower output back underneath to move some air under the helmet, or if I find it isn't necessary, pipe the air to the eyewear.

This is the fan I have:

https://www.digikey.ca/product-detai...475-ND/2560599



This is what I have for a battery pack:

http://www.ebay.ca/itm/391274123234?...%3AMEBIDX%3AIT


The fan it seems will not turn on unless it gets 7v of power, the battery pack only outputs 5v.

So from doing some searching, I need a voltage step up converter, to convert from 5v to 12v. This I can find on ebay for about 5 bucks.

like so:

http://www.ebay.com/itm/mini-5W-USB-...item3f4b1d532a





Here's what I would like to know:

is there a boost converter that will allow me to change the voltage on the fly from a wheel or switch that will allow me to throttle voltage to control rpms of the fan? at 12V the fan is loud but moves a lot of cfm. So I'd like to be able to run the fan at 9v and have the option to provide more air as needed. The pack has a 1A output, and I think that would be more than enough for the fan.

given that this is a lipo disguised as a usb battery pack, would there be a low voltage cutoff, and would I need one? I would say yes, because there's nothing like having a lipo strapped to the back of your head... especially when it's on fire.


I will also need to source a switch to wire to somewhere that isn't on the back of the helmet, and find a suitable casing for the fan and battery to shield from BB hits and elements. I will vent the bottom of the casing so it has an air source. The other item I need is a duct system, I think I can easily find something round, the issue will be to mate it to the rectangular output from the fan. but that seems relatively minor finishwork.


Any suggestions?

[chaz]

How about a setup like this?
http://www.actionfans.net/

[silent_lemon]

squirrel cage fans are super loud by virtue of their design, if you want to move more static CFMs then i suggest stacking two small PC style fans.

[lurkingknight]

Originally Posted by chaz

How about a setup like this?
http://www.actionfans.net/

that's essentially what I'll be building.

[ThunderCactus]

OR just use a pair of small PC fans and power it off a 7.4 lipo
You can use a rheostat to control fan speed.

[lurkingknight]

I'm hesitant to put fans inside the helmet in case my hair gets sucked up into them. Also I'm hesitant to use a lipo as a powersource due to the more fragile nature of them.

[ThunderCactus]

Fragile?
Its a 7.4v battery powering 0.3A worth of fans. What are you expecting to go wrong? Lol

[lurkingknight]

you underestimate my bad luck. lol.

[chaz]

i will try to dig it out but i made one using the cooling fan from a laptop. moved lots of air and ran for 12+ hours on a standard 9v battery

[SuperHog]

Originally Posted by chaz

How about a setup like this?
http://www.actionfans.net/

Agree. One of the best ways to get airflow into the helmet.

As for noise, just run less batteries or wire in a potentiometer to bring down the fan speed until the noise in not noticeable.

[Kos-Mos]

Originally Posted by SuperHog

Agree. One of the best ways to get airflow into the helmet.

As for noise, just run less batteries or wire in a potentiometer to bring down the fan speed until the noise in not noticeable.

Not a viable option for a turbine... they need to run at full speed to be efficient at all.

But as other said, just get a standard fan.
Your hair won't get sucked in since you are pushing air into your helmet.
And they are not even near strong enough to grab and pull anyways. (I installed one on top of my googles, hair getting in just stops the fan, they are really weak.

Why are you affraid of running a fan on a LiPo? Running guns on them is way more dangerous.

[lurkingknight]

You can see and drop a gun that's on fire, you can react to a situation much faster than if it's strapped to the back of your head.

it's not so much the lipo running the fan that is my concern, it's things hitting the head helmet/battery and it's strapped to my head, and in a spot I can't see it. If I'm going to run a higher voltage pack, it will be a lifepo4 which is much safer and doesn't catch on fire when it shorts/cells are damaged.

I'd much rather use a small pack, that can be encased in a small module with the fan itself. No fire risk, no risk of anything being pulled into the fan accidentally.

[Porkchop]

I'd like to recommend this model:


low noise, low drag, dubious effectiveness.

[ThunderCactus]

Originally Posted by lurkingknight

I'd much rather use a small pack, that can be encased in a small module with the fan itself. No fire risk, no risk of anything being pulled into the fan accidentally.

You mean like a LITHIUM CR123? lol XD