SpudFiles

I saw they make a 5v version of brushless fans. Is there any adverse effect on the fan if I used a 9v bettert to run it faster?

My reasoning is that it's better to have more flow from running a 5v fan faster rpms at 9v than to have an underperforming 12v fan runninf at 9v.

Yeah I know I can just buy a 12v battery but... nah.
9's are cheaper and I don't want to mess with wiring two AA bateries with a 9v to get 12v.

So will the 5v fan burn out at 9v? It's not like it will be running constantly, just a few seconds at a time to mix air and propane.

I would personally go for a 12v fan, with a mixing tube.

But i guess both solutions work, just make sure u mount the 5v fan so its easy to replace if u burn it with 9v , but its usually not a problem.

I dont think it would matter , ive done it before my dad always told me the fan will draw what it needs, there isnt much amps coming out of the battery so it wont burn it up

If the motor's internal resistance is 1 ohm, then at 5v it'll draw 5 amps, at 9v it'll draw 9 amps. That's enough to shorten the lifespan by a fair amount, but for your uses, it won't matter much.

^^^^ This is true if the motor is not turning.. When the motor turns, the current drops well below the DC resistance current value. When the motor runs, it self generates some so the Back Electro Motive Force (EMF) reduces the current draw.

Most small fans are brushless with electronic commutation. The current is less of a problem than the overvoltage may damage the electronics in the motor.

Larger AC motors have a couple of currents stamped on the nameplate.. LRA (Locked Rotor Amps) which is what limits the surge current when power if first applied. Power first applied to a motor is when it is NOT turning. The Fuse or Circuit Breaker must be designed to handle this higher current. The other current is the RUN Amps, which is the normal current with the motor running under a normal load.

I got a 12v D brushless fan and wired two 9v batteries together on a pushbutton switch. It's been working so far, it's a large fan in a 4" chamber so it mixes the air well and fast. You aren't holding the button down for long periods of time. I think it will last as long as I need it to, it's not running constantly as if it would in a computer.

Do any of you forsee issues later down the road with it? Eventually the 18v will drop anyway as the life of the batteries drains and it will only get closer to the 12v intended power.

Yeah?

I like to use the LM2577 DC-DC Adjustable Step-up Power Converter Module - you can find them on eBay for just a few bucks.

I use it to run the fan on 3 or 4 AA batteries.

Really small - I put it in an altoid tin with fan and ignition safety switches.