Car radiator fan

Projects General Guidance
1

A complete newbie would like to run car radiator fans with the following parts:

  1. Arduino nano board
  2. DS18B20 temperature sensors, 3 ea (coolant temperature and AC condenser temperature)
  3. ADXL345 accelerometer sensors, 1 ea (senses vehicle movement)
  4. Small relay boards, 2 ea (low current, interfaces with Arduino)
  5. Automotive relays (high current, controls fans) , 2 ea

In general, all radiator fans are controlled this way: when coolant temperature is high or AC condenser temperature is high (AC is turned on), fans are powered. But when car is moving, don't run the fans. Natural air movement through the radiator does the cooling.

What I would like to ask you to review is if the components will withstand car environment.

  1. DS18B20 will be directly mounted on the engine/tubing. Will they take the mechanical vibration?
  2. A DC-DC buck converter will provide 9V power to Arduino board.
  3. Arduino board with buck converter, small relay boards, and ADXL345 sensor board will be in the passenger cabin. I will use potting compound to secure them mechanically.

Thank you.

2
  1. ADXL345 accelerometer sensors, 1 ea (senses vehicle movement)

There's no acceleration/deceleration when you're moving down the road at a constant speed (except for vibration from bumps in the road).

  1. DS18B20 will be directly mounted on the engine/tubing. Will they take the mechanical vibration?

That should be fine as long as the connections stay connected. Solder and heatshrink and I wouldn't worry.

  1. A DC-DC buck converter will provide 9V power to Arduino board.

That might not be necessary. The Arduino is rated up to 20V and it's usually OK unless you have a higher voltage AND you power "extra stuff" from it's regulator. ( I've got an Arduino running directly off the '12V' in a car.)

I will use potting compound to secure them mechanically.

Of course, that makes non-serviceable.

3

DVDdoug:
There's no acceleration/deceleration when you're moving down the road at a constant speed (except for vibration from bumps in the road).

That should be fine as long as the connections stay connected. Solder and heatshrink and I wouldn't worry.
That might not be necessary. The Arduino is rated up to 20V and it's usually OK unless you have a higher voltage AND you power "extra stuff" from it's regulator. ( I've got an Arduino running directly off the '12V' in a car.)

Of course, that makes non-serviceable.

Thank you for the reply. A few follow-up questions.

  1. Accelerometer: What would you recommend? Vibration sensor?
  2. Buck converter: I added it just because someone mentioned how "dirty" the 12V is. I am glad to know it is not needed.
  3. Potting compound: Is this not necessary in your experience?

Thank you.