Safe using a 12V 80mm PC fan without additional hardware?

[pigod]

I have a spare 80mm PC fan. I like the fan because it is quiet. There seem to be small fans specialised for Pi, but I have a bad memory with small fans (not for Pi); They were very noisy.

According to the manufacturer, the fan uses 12V and 0.08+-10%A (that is, 72mA ~ 88mA, I think). Its cable has three ports at the end, and I connected the fan's Ground and 12V port to Pi's Pin 4 and 6, and the fan began to spin and it is very quite (almost inaudible). The Pi4 does not overheat for normal usage any more.

Now, is it safe to keep using this fan like this for a long time? I don't know much about electronics, but do I need to add something to protect the Pi4, like a resistor or something? I don't care whether the fan dies or not; it is a cheap fan.

[HawaiianPi]

As long as the fan can run on 5V it's fine (not all 12V fans can reliably run on 5V).

I used to have a double stack of a Pi and Tinkerboard with a single 12V fan cooling both, powered by 5V from one system.

Let me see if I can find a picture...

Pi-Tinker_double-trouble.jpg (119.6 KiB) Viewed 465 times

The top case had its own fan, but it's not connected (you can see its power plug hanging in front of the 12V fan near the top-right corner). Both systems were cooled well by the one 12V case fan, and that was powered from the Pi's GPIO header 5V power and ground pins.

[Imperf3kt]

I don't use one myself, but a diode may help avoid potential back-emf damage when turning the fan off.
Note though, that a diode may prevent the fan from spinning by dropping the voltage too low. It'll also spin even slower.

[davidcoton]

I don't use one myself, but a diode may help avoid potential back-emf damage when turning the fan off.
Note though, that a diode may prevent the fan from spinning by dropping the voltage too low. It'll also spin even slower.

Back-EMF protection usually puts a diode across the fan, rather than in series, to conduct reverse voltages ("inverse parallel"). There is some debate whether it is necessary for a fan motor -- particularly since the Pi (except Pi0 models) already has reverse polarity protection (TVS diode) on the 5V supply.

[Imperf3kt]

Woops, mind slipped.
I was hanging laundry while writing that, so wasn't thinking fully.

Thanks for clarifying.