Running 12v fans in series one pitfall to avoid

  • So when I built one machine which is 24v I had plenty of 12v fans lying about, and wired two in series as hotend cooling fans. to get 12v/fan I have noticed one small pitfall, at low speed (which I use with ABS to keep overhangs in check) only one fan runs. One obviously has lower resistance than the other so one runs and the other doesn't unless I can set them over 30% (these are 30mm sunon blower fans). As such curling edges were more of a problem with one sided cooling than with none.

    So something to watch out for. Might rewire them with a buck converter at 12v parallel until they need replacing then go for 24v fans.

  • I would say that "resistance" in a PWM controlled coil voltage/current chopper is a bit stretched.

  • These fans take so little current I would try a 1K ohm 1/4 watt resistor across each fan to even out the voltage division.

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