Raspberry Pi Temperature control Implementation Research

Owned by Akshayan Ahilan (Unlicensed)
Last updated: Jul 08, 2020
3 min read

-Usually, the Raspberry Pi 3B+ heats up to 60 degrees Celsius under 0% stress of the CPU

-To operate the Rpi 3B+ at maximum power for extended periods of time, a small heat sink or fan implementation is required (goal of this task)

-Flirc Case? Possible suggestion from Raspberry Pi Forums, acts like a giant heat sink, $15.95 from Amazon

 

 

Power Consumption Benchmarks of RPi 3B+

Pi State

Power Consumption

Idle

350 mA (1.9 W)

ab -n 100 -c 10(uncached)

950 mA (5.0 W)

400% CPU load stress

980 mA (5.1 W)

 

List of Loads/Applications for RPi 3B+

-infotainment display

-telemetry data

-input from dash buttons

-GPS Navigation

-Dash-Cam recording

-Parking Sensor

 

Finding the best Solution for Temperature control on Raspberry Pi 3B+

Description of Options

Pros

Cons

Practicality/easiness

Option 1: Implement a fan control IC in the Center Console (to use Rpi’s built in thermistor to get temp sense data)

  • Firmware independent 

 

  • potentially will work on center console

 

  • Can measure fan speed easily (makes sure the fan doesn’t break)

  • The IC is bigger (takes up more space)

 

  • More Expensive than it needs to be

 

  • It can control 4 fans and have many features that will not be used

 

  • Ordered different fan controller for testing (part number: ADT7476A)

 

 

 

Option 2: Implement a fan control on the Center Console (to use Rpi’s built in thermistor to get temp sense data)

  • Can measure fan speed easily (makes sure the fan doesn’t break)

 

  • Can be integrated with Center Console and RPi

 

 

 

  • Firmware dependant

 

  • IC will take up more space than wanted

 

  • it is less cost efficient, in comparison to other solutions

 

Option 3: Implement a Bimetallic Switch, at temperature threshold, it will turn open, allowing the fan to turn on/off

 

  • easier to control the fan as on/off with a switch

 

  • implementation is very straight forward

 

  • it is robust

 

  •  cost efficient

 

  • not very accurate and responsive towards various changes in readings

 

  • not suitable for measuring lower temperatures (Since metallic alloys show same contraction and expansion in lower ranges of temp)

 

 

 

 

 

 

Option 4: Fan is always on, and we can turn it off with the center console as an option 

  •  This option is very cost efficient, as we would only be needing items such as a remote control, etc.

  • firmware independent

  • there will be a lot of energy loss, since fan is consistently on

  • Inefficient (to keep Turning the fan on consistently)

 

Option 5: use a small fan controller for temp sense 

  • saves power by not running the fan at full speed

  • can run in automatic mode, so additional computations by the RPi aren’t required 

  •  Costs much less than the IC in the BMS Carrier

  • Can control the fan without any extra firmware as needed

  • directly measures temperature of Rpi when placed in contact with it

 

 

  •  Additional energy losses and noise when motors are operating at higher loads

  • Increased Maintenance

 

Based on the advantages and disadvantages of each option, I feel that the most effective solution would be to use a small fan controller to measure temp sense (option #5).