Running the E3D-v5 from a non-12v PSU

Discussion in 'E3D-v6 and Lite6' started by Josh, Feb 27, 2014.

  1. Josh

    Josh Administrator
    Staff Member

    Feb 26, 2014
    Likes Received:
    This question comes through to E3D support quite often, so I just wanted to clear up any confusion, and answer some common questions.

    While the E3D is designed for 12v, there should be no problems running it at voltages within a sensible range of this (i.e. 11 - 24v). Many customers report running the HotEnds just fine with a 24v psu with a little bit of firmware tweaking.

    Heater Cartridge
    The easiest way to limit the current in the heater cartridge is in the firmware.

    In Marlin you could update configuration.h to be something like:
    #define PID_MAX 50
    If that heats up too slowly you can (cautiously) increase the number 50 to something higher.

    The fan is rated by manufacturer from 7v - 13.8v so if you are in this range, then no changes need to be made.

    If you are at a higher voltages, then you have 2 choices:
    1. Use the PWM output from your controller through the use of the extruder cooling fans feature.
    2. Use a resistor to limit the current.

    Fan - Using PWM
    1. Connect your fan to the controller.

    2. Open up your Marlin configuration_adv.h file and assign the pins accordingly.
    // Extruder cooling fans
    // Configure fan pin outputs to automatically turn on/off when the associated
    // extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
    // Multiple extruders can be assigned to the same pin in which case
    // the fan will turn on when any selected extruder is above the threshold.
    #define EXTRUDER_0_AUTO_FAN_PIN   7   // For the RUMBA 
    #define EXTRUDER_1_AUTO_FAN_PIN   -1
    #define EXTRUDER_2_AUTO_FAN_PIN   -1
    #define EXTRUDER_AUTO_FAN_SPEED   128  // For 50% duty cycle on a 24v PSU 
    If you can't find this feature in Marlin then you may need to update since it has only been introduced recently.

    3. Then go and remove your fan in pins.h
    #define FAN_PIN            -1  
    This implementation will be board specific so please do comment on your experience.

    Fan - Using a Resistor
    The fan has a current rating of 70mA at 12v giving it an effective resistance of 170Ω.

    You need to limit the current in the circuit to 70mA, if you had a 24v PSU the total resistance needs to be:
    24v / 0.070A = 340Ω 
    Which means you will need a resistor of:
    170Ω - 340Ω = 170Ω

    The resistance of the thermistor is normally measured in a potential-divider circuit on your board which will normally has a 5v regulated supply so will not need to be changed.

    With all of the above said, I can't make any promises about running the HotEnd at anything but 12v because individual printer setups vary so wildly, the advice above is based only on feedback from customers - not personal experience.

  2. rsilvers

    rsilvers New Member

    Apr 3, 2014
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    I am running mine at 24v.

    I use two fans - one on the Filament drive, and one on the E3D. They are both identical: ... UTF8&psc=1

    And I run them in series on a MakerGearM2 after bypassing the case fan.

    They are super quiet - the printer is now way more quiet than the power supply.

    I ordered some 24v heaters, but I just tried that current limit firmware mod, and it worked. I didn't need to order the heaters after all.
  3. Josh

    Josh Administrator
    Staff Member

    Feb 26, 2014
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    Using 2 fans is a good idea.. cheers for the tip!

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