Mask fans, volts, amps and things I don't understand

[skarra333]

Hi guys.

I'm after some help please.

My Mask fan is on its way out now, and I'm looking to replace it myself, rather than pay £35+ for a ready made replacement.

I am currently using an old Fanz single fan (similar to this one - http://www.ebay.co.uk/itm/FANZ-Anti-Fog-Goggle-Fan-Single-Unit-Paintball-Goggle-Mask-Fan-CC-3-/390571896437), which I understand is a 9v fan, and it runs of a 2XAAA battery box...

What I'm thinking of doing is getting 3 of these (1 fan just doesn't cover my goggle area sufficiently):

http://www.maplin.co.uk/p/30x10mm-cooling-fan-a27gu

OR

3 of these http://www.maplin.co.uk/p/8mm-cooling-fan-a25gu

Along with one of these:

http://www.amazon.co.uk/Leads-Switch-Black-Battery-Holder/dp/B00CQKCWBW/ref=sr_1_24?s=electronics&ie=UTF8&qid=1434361162&sr=1-24&keywords=aaa+battery+box

Now I know how to make it all fit/attach and what not, but I'm struggling to understand how it will work in terms of amps, volts etc. Any help and advice is very much appreciated.

For example, I'v read in various places that using a 12v fan on a battery source that is less that 12v will lead to explosions...

Will a 2XAAA battery box safely run a 12v fan - or 3 of them? If so, what sort of battery life can I expect?

Do I need to set the wiring up in a certain way (i've read stuff on series vs parallel wiring but don't understand it) in order to get sufficient power to the fans, without overly draining the battery?

And should I be looking at other things, like a 9v fan (which, for a reliable one, seems surprisingly difficult to source, for me at least), as Maplin sell 9v battery boxes?

As I say, any help, especially from people who know about electricity is appreciated.

Many thanks.

 

[TheGrover]

From my principle understanding of electricity, using a lower voltage source than the component is designed for is safe, but you won't be getting much bang for your buck, one AAA battery only supplies 1.5v, so you've already been running one off 3v.

And its best to figure out your series and parallel wiring, if I were you, I'd link all the necessary batteries in series, then link the fans in parallel so they Don't "share voltage", it drains the battery faster, but 1v per fan won't do much good.

As long as you keep it simple, forget about the amperage, just make sure that no fan is powered with a greater voltage than its rated for, and you'll be fine

 

[Samurai]

The first link is saying it's 9V powered. That means the battery is a 9V battery, the fan itself is a standard 12V one IMO. A 12V fan running on 9V spins slower thus less airflow but less noise too.

Does it actually run on 2xAAA? That's only 3V and I would think it doesn't move on that low voltage. If it does it must be very quiet, but that would explain why one fan is not enough for you.

Get one or two 12V fans and run it on a 9V battery. That's low noise level with still a decent airflow and the battery is smaller than the AAA packs.

As TheGrover said, link the fans in parallel. That way they still need 12V but will drain higher current, meaning the battery will go flat faster.

It's generally not a very good idea to link batteries in parallel to get bigger capacity. If they are not the same brand and on the same voltage level, the higher one will try to charge the lower one and batteries don't like that. If you use rechargeable batteries, then that's not a problem.

But I think using a 9V battery in your current setup will solve your problem.

 

[BrightCandle]

Most fans rated for 12V wont start on anything less than 6V. I doubt 3V would be sufficient.

 

[skarra333]

Hi all.

Thanks for the responses on this - I think i've understood what I need to do and appreciate the help.

The current fan certainly does run on the AAA's and I get about 5 hours game play out of them. But as you say, if it's running on such reduced power, that might be part of why it doesn't do it's job brilliantly. I also use a V-Force profiler lens. The goggle itself is comparatively quite large and the width of the curve may also be why the far left and right edges of the goggle are where moisture starts to build. The 2 or 3 fan approach, with a 9v battery should solve this.

I'll put a before and after piece on the forum somewhere when it's done.

Thanks again.

 

[cyrexx]

Have you considered looking at using 18650 batteries? They have a higher voltage and a lot more capacity than AAA batteries. Plus they are rechargeable.

 

[n1ckh]

A 12v fan will work off a 9v battery

BUT do not wire them in series because if one breaks then the other will not work because the circuit has broken

Your better off using a 9v battery on each fan as one battery dies then the other will still work

Your battery will die within minutes if powering 2 fans from one battery

 

[skarra333]

I admit I'd never heard of 18650 batteries before this. But they're worth exploring.

In advance of replacing my fan i took it apart enough to see the specs on the blade unit - it is actually a G&G 5v fan with a 0.8w something.

So I'm still not sure why my 2 regular duracell AAA's run it, as that's just 3 volts as I understand it.

That being so though, I'm hoping running a 12v fan on a 9v battery will be ok. If i'm only getting 60% of the power needed as is, going to the new set up will get 75% of necessary power over 2 fans at least? How long it'll last is another matter. This is all new to me so trial, and a fair bit of error might be in the pipeline.

 

[BrightCandle]

Most fans will start at about 50% of their rated voltage they just run slower. On PCs I have used this fact for years to reduce 1300 rpm fans down to the 800 rpm range (nearly inaudible) with fan controls or basic voltage division to 7V from their usual 12V rating. Fans typically come in 12V but Evercool appear to also do 5V ones as well.

It is quite easy to work out the run time of a battery. Most batteries come with a size in Amp Hours (or milli amp hours) and if we know how many amps the fan consumes we can work out how many hours it runs.

So looking at the 18650 they look to be 2500mah. We also need the spec sheet for the fan which I believe is this one: http://www.evercool.com.tw/categories/global/fan/imges/3010.pdf. The fan consumes 0.08A at 12V (at a lower voltage it will decrease the spin speed and usually power consumption as well).

2500 mah = 2.5A hours

Fan is 0.08A

2.5 / 0.8 = 31.25 hours

But we aren't going to run it at 12V, we are likely going to run it at 7.4V with 2 batteries. So its probably 12 / 7.4 = 1.62 times longer, so 50 hours per battery. But then if you intend to run 3 batteries off of these you would only get 17 hours out of it.

 

[BrightCandle]

So what about a basic 9V battery? Well according wikipedia the basic alkaline ones are 565mah. So 0.565A. That puts it for one fan at roughly 0.565 / 0.08 = 7 hours. With the reduced voltage and hence spin speed of the fan you may see more like 7 * 1.61 = 11 hours. 3 fans off one battery? more like 3.5hours.