How long does it run on a full charge? I use a variac and a 120 volt fan with a carbon filter, but it's showing it's age and is starting to rattle. I do like the lower noise of modern PC fans (the 120 volt fan I use was taken from stock for an 8.8 kW (peak 13 kW) industrial brushless motor driver. I used to service them at my old job. Great flow, but it comes with noise. I always crank the variac down to around 70 volts, just to reduce noise, but it's right at the threshold of "sucking range" cranked that low.

I ask about the battery life though, cause I often solder for hours a day, sometimes longer than 8 hours. I could always invest in a battery charger of some kind, to keep the batteries topped off, and then swap as needed, but then again, I could also get a 12 volt wall wart too. I do like the mobility factor though. I could move it to other spots to work.

I'd also like to reuse my carbon filter housings, which are 120mm. It'd make sense then to buy a 120mm PC fan. I suppose that'd use even more power yet... Course, bigger could also mean bigger batteries too.

The most I've used mine in one sitting was probably 3 to 4 hours. The total run time would be dependent on the amp hour capacity of the battery as well as the draw current for the fan.

Simple, practical, and manufacturable. That hits all the checkmarks for a kickstarter imo

Thanks for the idea! I'm just glad to see people interested in it honestly. I wasn't thinking it would get that much attention. 

maybe you can couple this with a smoke detector and have it turn on and off automatically

Thanks, that's a cool idea!

It would work if the smoke detector is an optical type not ionization type.

https://en.wikipedia.org/wiki/Smoke_detector#Photoelectric

May be easier to have a microswitch / magnet reed switch to detect when the soldering iron is off the holder and use that to switch on the fan.