Comparing Raspberry Pi stats: CPU temp & RAM

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Continuing the discussion from Emoncms v9.7 - Emoncms admin Raspberry Pi system stats & reboot:

Here is a screen grab of the stats my emonPi:

  • Raspberry Pi 3
  • Connected via onboard Wifi
  • Ambient temperature approx 15 deg C
  • emonSD-03May16
    • nodeRED
    • OpenHAB

I’m interested to find out how these stats CPU temp, RAM usage etc compared to other users also running an emonSD? I’m not particularly concerned but a CPU temp of 43 deg C seems quite warm given the ambient temp of about 15 degC!

Hi Glyn,

I recently put a node in node-red to read the Pi temperature and log it to my local emoncms. This is a Pi zero with 9.31 (I think) installed following the raspi installation instructions on Jessie Lite. I’m running MQTT and node-red as well as emoncms but not much else. So a similar system to yours.

The Pi temperature averages 40C within a degree or so and I think if you’ve read the Pi forums you’ll find that Pis run warm all the time, so I reckon around 40C is fine. I guess if you are doing heavy compute type applications then it would run hotter but with the stuff we are running it’s hardly ticking over.


PS My system runs on a USB HDD but I wouldn’t think this would matter much.

PPS no RAM usage, guess I ought to check some time but while things are running fine, I’m not that concerned about that.

I have an AVG of 40deg.
I use latest emonSD on a PI2

The CPU temp is probably as expected in it’s case, for re-assurance check this video
My Pi2 runs at 35 deg, but it’s on a HDD and a (very well) ventilated case.


The metal emonPi case should be better at heat than a plastic case, there is actually quite a bit of space in around the RaspberryPi. The Pi3 does get much hotter than the Pi2

here are my numbers:

EDIT: mid-2015 emonPi. 8GB SD card. Left end panel removed to make changing SD cards easier.

  • Raspberry Pi 2
  • Connected via ethernet
  • Ambient temperature approx 20 ºC
  • emonSD-03May16
  • nodeRED

This is a 2015 EmonPi still using the supplied 4Gb SD card:

The system is in a garage on a NW facing wall, ambient currently 13C. I also put a spare DS18B20 on the heatsink fins of our SolarEdge 5K inverter next to it and am surprised to find it never gets above 35C !

Thanks OEM team and all contributors for a really good system…

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Good to know my Pi is excessively hot.

Interesting to see that @derekb has slightly lower total RAM than me and @Jon

The Pi’s are reportedly good up to 55C, I managed to push one to 50C when testing a very small Pi case.

I think 43 is a bit high but not a huge concern. I have one Pi that I monitor runs at a constant 43C, although the loading is quite light the Pi2, RFM2Pi, 3x emonTxs and 4x wallwarts are installed in a snug sealed box in a warm plant room, but the Pi only runs emonHub for forwarding only

The RAM difference will be the gpu_ram allocation reduced from 64 to 16 Mb on recent images.

Ah, good point :thumbsup: