agus97v
Posts: 5
Joined: Thu Apr 25, 2019 1:32 am

Power fans to cool Rpo 3B+

Fri May 03, 2019 9:59 pm

So, here's my situation, where I live the ambient temperature can be a bit high in spring/summer (around 40°C and sometimes more) and I need my rpi to be in an enclosure and to remain cool. Sometimes it's under heavy load as I use it to stream movies or shows via upnp and also to control a 3d printer. I found an enclosure on thingiverse that resembles a computer case that can be seen in the game portal. What's good about this case is that it has space for three 30mm fans and one 40mm fan.
I have read in several places that's a bad idea to plug a fan to the rpi pins (at least directly). How could I power those fans?
I guess I need an extra power supply for them.

Thanks in advance for your help.

Pd: I'm not an expert in electronics but if I have the schematics I can solder components with tin

Icosagon
Posts: 26
Joined: Sat Apr 13, 2019 12:32 pm

Re: Power fans to cool Rpo 3B+

Sat May 04, 2019 10:14 am

This is a very basic question. :)

First read whats written on the computer fans power requirement (most of the are 12v). Soldering isn't required for this. Just connect the positive wires of every fan and negative wires of the fan.(+ & - separately) and use any 12v DC adapter to power them. That's all. :lol:
If you want to control the speed of the fan you may have to use a motor driver and it is advanced.

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HawaiianPi
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Location: Aloha, Oregon USA

Re: Power fans to cool Rpo 3B+

Sat May 04, 2019 4:00 pm

agus97v wrote:
Fri May 03, 2019 9:59 pm
...
I have read in several places that's a bad idea to plug a fan to the rpi pins (at least directly). How could I power those fans?
I guess I need an extra power supply for them.
If the case is well ventilated a large heatsink may be enough. The 3B+ has much better thermal management than the older 3B model.

I have most of my Pi 3B and 3B+ computers in generation 2 Flirc cases.
Image
The Flirc aluminum alloy case acts as a huge heatsink without the noise, dust or additional power requirements of fans.

My test bench Pi 3B is in an open sided acrylic case with a 40x10mm Noctua 5V fan that keeps it well under thermal throttling temperatures at full load, with no heatsink. The Noctua NF-A4x10 5V fan is a little pricey, but it cools well and is so quiet I can barely hear it. I have it connected directly to the Pi's GPIO expansion header +5V and Ground. Before I got the Flirc cases I had several other Pi computers with fans powered the same way and never had a problem.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

achrn
Posts: 421
Joined: Wed Feb 13, 2013 1:22 pm

Re: Power fans to cool Rpo 3B+

Sat May 04, 2019 8:19 pm

agus97v wrote:
Fri May 03, 2019 9:59 pm
I have read in several places that's a bad idea to plug a fan to the rpi pins (at least directly). How could I power those fans?
I guess I need an extra power supply for them.
You can't run a (useful) fan on the actual GPIO pins directly, but there are power pins in among the other header pins on the pi that will run small fans OK. So if you have a smallish 5V fan, you could connect that to any of the '5v Power' and 'Ground' pins shown on https://pinout.xyz/# (The actual limiting current you'll get from those pins depends what else you're doing and what your power supply is capable of).

As noted, if you want the fan to be controlled (whether just on/off or with speed control) you'll need some circuitry - a transistor, resistor and diode would be the minimum to do it. You'd need a circuit like the option 'driving a relay' at https://elinux.org/RPi_GPIO_Interface_Circuits but in your case put the fan in where it has the relay coil (wiggly line at the top of the diagram). You'll also need to do some programming to control the fan, so maybe you don't want that (yet).

Moonmarch
Posts: 492
Joined: Thu Mar 07, 2019 1:34 am

Re: Power fans to cool Rpo 3B+

Sun May 05, 2019 2:45 am

Search for USB powered fans from any electronics website or google shopping, the RPI case will need holes for ventilation. If the USB cable on the fan is not long enough, you will need to buy USB extension cables. Larger fans are more effective than smaller fans, larger fans generate less noise.

The RPI doesn't overheat until the CPU temperature reaches 85 C, you can check the CPU temperature using a panel applet on the desktop, right click on the task bar, then add/remove panel items.

jahboater
Posts: 5926
Joined: Wed Feb 04, 2015 6:38 pm
Location: West Dorset

Re: Power fans to cool Rpo 3B+

Sun May 05, 2019 6:59 am

Use

Code: Select all

vcgencmd get_throttled
If it returns 0x0 then all is well and it has never throttled back due to overheating (or low PSU voltage) since the last boot.

agus97v
Posts: 5
Joined: Thu Apr 25, 2019 1:32 am

Re: Power fans to cool Rpo 3B+

Mon May 06, 2019 4:45 am

Considering that I'm using all 4 USB ports I guess I'll buy an external 12v supply and some fans.
I'll look up on how to control them based on the cpu temperature when I'm feeling more confident with my electronics skills.
Since I posted this topic I managed to attach an rgb led that lights up in different colors according to the cpu temp. That way I have a visual cue on how hot it is.
Thanks for all the help 😀

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