Turning on a SMALL fan.. 24MM

I have been looking at options for turning on a small fan (About 24MM round.). It’s rated at 12V, minumim 6V. About 150 mA draw. I will be using a 7.2V supply. (li-Ion, range from 6V to 8.4 although at 6V it will probably be too “dead” anyway)

It draws too much to be turned on directy via Arduino pin, and since I will be pushing the lower end of it’s supply voltage range I would rather not have a significant voltage drop. My understanding is that using a transistor or solid state relay would mean about 1V of voltage drop?

Is my best bet a mechanical reed relay (like the Rat Shack reed relay… #275-232) and a diode to shunt the flyback voltage?

A mechanical relay would do the job (you'll still want to use a transistor to drive it); but have you looked into devices like MOSFETs?

Also - what is preventing you from using a larger voltage supply for the fan (or a lower voltage fan)? You are already right at the edge of what the battery can supply - I hope this supply isn't the same one for the Arduino, otherwise you are looking at possibly getting some interesting errors (your sketch boots, turns the fan on, dropping the voltage to the Arduino, causing it to reset - etc).

You might want to look into other options, if they exist (another possibility might be to use a voltage booster for the fan)...

Good luck! :)

It's a 7.2V. 2600 mAH Li-Ion battery pack.. I am kind of stuck with it. I can't really fit a bigger pack in the project (A lightsaber).

I can indeed get a lower voltage fan... I'd rather do it with what I have if I can. But, if I'm going to have to order something anyway, it's not that big a deal. (I've already done a ton of small orders through Mouser.. LOL... $4 in parts, 8$ shipping....)

I will look in to MOSFETS and see if it looks like it may work better.