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So I am looking for advice on how to ‘control’ a bank of two PC case fans which will be used to boost the air flow ( usually a natural draft airflow)over an RV refrigerator evaporator during high ambient temperatures to maintain the internal temperature of the refrigerator to around 3 or 4 degrees C. The fans are Arctic F14’s which are ‘full speed’ at a nominal 12v and ‘half speed at a nominal 6v. I was thinking ( for simplicities sake) along the lines of using a thermistor mounted within the refrigerator which would at around 5 degrees give a supply to the fans of around 6v and if and when the temperature continued to raise then at above 6 degrees it would provide the fans with full battery voltage until a nominal 3 or 4 degrees was reinstated. An incremental / proportional increase would be even better ! Thanks for any advice etc….. Incidently if the temperature range is too tight then a couple of degree tolerance might be acceptable.......! |
August 28, 2025 |
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It is preferable to use a pulse width modulation (PWM) so that the "average" voltage can vary with the duty cycle (duty cycle at 100% => 12V, duty cycle at 50% for 6V), as you can do when you wish to "dim" a LED, as example. If you use a variable resistor (here, a thermistor), you may lose a lot of energy through that resistor, uselessly. The PWM is more energetic friendly. |
August 30, 2025 |
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