What type of fan to use for the osr2 fan lid?

i have found multiple 40mm fans but I’m wondering which one to use, for example the best one i have found is a 5v 10000RPM 40mm fan (shown below) but im wondering if it will ruin my romeo ble mini v2 since others at the same voltage and price range give less sometimes even less than half of the rpm in comparison

is it safe for me to use this one? if not what should be a rpm i should aim for?

I forgot to mention but im not using a power bus for the servos, its the base osr2 with a fan lid and the servos connect directly to the romeo

I’d use the 12v version of the noctua 40mm fan. I’m not sure if the thickness of the fan you showed will fit in the OSR2.


I’m guessing you’re running your servos at around 7v. The Noctua will spin slower, but will be quieter and have enough airflow to cool the 2 servos. Running a 5v fan at servo voltage will be a recipe for a jet engine and will eventually burn out.

Im using 2, 30kg cm servos that have an Operat Voltage of 4.8V - 7.4V. A Noctua fan is too expensive in comparison to other fans available in the country that I live in. Will any of these 2 work?

  1. Cabinet Cooling Fan 40mm 1.5Inch 12V 3000RPM For Raspberry Pi, Nvidia Jetson, 3D Printer Size 40X10mm

  2. CentIoT - 4010 5V DC Brushless Cooling Fan XH2.54 2Pin Sleeve bearing 5500rpm - 40mm x 40mm x 10mm Ventilation Cooling Fan (suitable for VGA, CPU)

get the 1st one, its 12v. the second one is 5v, and as I mentioned would have a very loud and short life if powered by your servo voltage.

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thank you :smiley:

I’d recommend this or this from Noctua. I use the thicker one for more airflow, though I also use my own OSR2 design (I added a fan lid before the official design had one), so I don’t know offhand if the thicker model will fit.

The Romeo BLE Mini board has 5V power pins, which you can plug the fan directly into, if you shave off the little guide rails on the connector. There’s no reason to power it with the same voltage used by the servos.

This is a key piece of information that I didn’t know. Always used powerbus + ESP32. @genji - this is a better option than my advice. @Thanny’s option allows you to use a 5v fan if desired. It WILL be running at full speed, so it might be loud.

The Noctua fans are pretty quiet. You can certainly hear that it’s on when you plug the board in, but there’s zero chance of hearing it over the servos in action.

totally agree, but OP mentioned that they’re too expensive in his country :frowning:

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