I'm having a sort of "issue" when using a Wifi dongle for my Raspberry Pi, after about 3 minutes connected to a router, the dongle starts to heat up quite alot, almost like a mug of coffee, which I find to be very concerning considering that the dongle casing itself is plastic and I don't want to damage the dongle or the Raspberry Pi itself.

This happens when I connect to the Pi via SSH when it's connected to the router wirelessly, now the heating is an issue to me because I was thinking of attaching a USB camera to it, and use it as a web server so I can connect to my Pi and view my camera. Since where I want the camera to be is quite impossible to pass a wired connection, I thought using a Wifi dongle would be a good idea.

Anyone know why my dongle is heating, or if it's dangerous in anyway? I was planning on leaving my Pi on permanently, like a server. What are the dangers of a wifi dongle, that I intend to leave switched on for days at a time?

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    It is a tiny dongle; like the same size as the usb plug? I have such a tiny one, and it's is getting quite hot too. My philosophy is that, if you can touch it without getting burned fingers, your fine. 60 deg C feels like a lot, but isn't all that much for electronics (and plastics). – Gerben Oct 17 '13 at 16:02
  • It's a dynamode nano 802.11n Wireless USB 150Mbps @Gerben yea a tiny dongle – BrownEyes Oct 17 '13 at 17:49
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    Just in case, I did put mine in the top usb port. That way more heat can dissipate via the usb socket to the air. As you might have noticed the usb socket getting hot too. – Gerben Oct 18 '13 at 14:00
up vote 4 down vote accepted

Unfortunately I don't have enough rep to just comment so I'll just put my answer here...

It would help greatly to know what the model of your wifi dongle is. E.g. a model no. I seriously doubt it is your Pi that is causing the overheating - mine has been on 24/7 using a wifi dongle and I have had no problems. I don't know off the top of my head the model of my wifi dongle but I am currently using the RasPi B board which is working flawlessly.

Re. your question about dangers: If it really is dramatically overheating then Yes is the simple answer - there may be damage caused. Anything outside of a controlled temperature that hasn't been tested on the board will cause issues, just like keeping your Pi board in the oven ;-) That said though, I wouldn't expect your dongle to overheat so much that it deteriorates your Pi board... In fact if anything I would expect it to take itself out before getting anywhere near causing damage to the board.

I'll check when I'm back which dongle I'm using - I'd certainly recommend it if you can't use a wired connection.

  • You can check if others have tried your dongle (and it works) here: elinux.org/RPi_USB_Wi-Fi_Adapters The dongle I'm using is this one: maplin.co.uk/… – Ash Oct 17 '13 at 15:28
  • It is not a compatibility issue. Its just how its designed. – ppumkin Oct 17 '13 at 16:02
  • It's a dynamode nano 802.11n Wireless USB 150Mbps – BrownEyes Oct 17 '13 at 17:49

No problemo...

That is not a problem at all. I have a realtek WiFi dongle that gets really warm. It is slightly worrying but it is quite common for Wireless dongles.

*some dongles get extremely hot!

Why does it happen?

I found a very generalised block diagram of a RN171 WiFi chip. This is a standalone unit that you can attach to other MCU like a Arduino. The highlighted part is the modules interface which is specific for these modules. As we can see there is a 32bit CPU and the Crypto Accelerator mentioned - Usually USB adapters will have some proprietary CPU and AES hardware. These will generate heat in different ways from different vendors.

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The AES encryption hardware usually built in to the chip, generates lots of hashes for each packet sent. It does not matter if its SSH or HD Video the chips spews out the same number of results each time. This process can also generate allot of heat.

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Because vendors try and squeeze everything in to the smallest area this usually means that they will generate a lot of area heat.

Solution?

There is no solution but try and research another WiFi adapter that runs cool.

You can try and run your network in open mode and see if that helps cool it down. This is not a long term solution obviously.

Disclaimer

Because all Wireless chip vendors keep their designs secret.. there is no actual way to prove or disprove my answer with factual references. Each chip vender have their own design and some USB adapter get hotter than others.

  • Thanks for the in-depth details! Don't know why the -1 though – BrownEyes Oct 17 '13 at 17:47
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    1. power required for AES generation is miniscule compared to the power required for radio module. 2. do you keep you car doors always open on a hot day, so it won't get hot while you're away? – lenik Oct 18 '13 at 0:07
  • ASIC Miner erupter - Yes AES is very efficient in power consumption and is very good at hashing!. But when in use it gets hot. When I lived in South Africa, yes - when it was 39 degrees celsius I kept my pick up windows open so that my dash wouldn't melt? But what has that got to do with AES.....................................?? – ppumkin Oct 18 '13 at 8:23
  • @lenik I understand what you mean with open car. Just be aware that encryption is just a false sense of security. There is no unbreakable code because just as humans.. its always flawed. If somebody will want to steal something from you they will find other ways to do it. Just ask the NSA, they know all about it (and they don't care what country you are in) – ppumkin Oct 18 '13 at 10:19

I have this same problem... but I have noticed it seems to happen more with n-band dongles... I have 2 Trendnet TEW-648UBM n-band dongles that work great, but they get considerably hotter than my 2 AusPi g-band dongles. You could attach a couple of small heat sinks directly to the top of the USB housings on the Pi to help draw off some of the heat.

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