12v Water Pump on a 24V System



  • @bearer thanks for your reply. I will have a look at what revision my board is. It would be great if it does.

    I thought about this however, I didn't want to do it as if I blow up a fan mosfet on the main board, I can still shift it to run off the duex2



  • oh, if your primary goal was to run it off the main board it has flyback diodes as of revision 1.02.



  • @bearer I was alway planning on running the Water Pump off the Duex2 and I may do the radiator fan off it as well. Is it just the heaters that don't have the flyback diodes as I had to put one on my air pump when I put it in. I forget. It was a while ago



  • Correct, no diodes on the heater outputs, just the fans. But if you already have a diode put on the pump then its a non issue, connect it wherever you like.



  • @bearer

    Yeah that is for the air pump. The water pump doesn't one at the moment. I believe I have a spare somewhere. It is just under an amp running at 12V so I may use one of the heater outputs on the Duex2 to drive the water pump just to be safe.



  • Gotcha. two pumps, just to keep it simple:D

    Worried about the current on the fan output? Duex fan transistor is good for 4.4A and the Fan connector i believe is rated for 4A.



  • Yeap haha. Should make it a quiet printer which will be good. I have to have it in the lounge and the wife hates it.



  • @bearer

    Just referring to one of your replies, are the Duex fan mosfets rated that high (4.4A)?



  • according to schematic and datasheet https://assets.nexperia.com/documents/data-sheet/PMV40UN2.pdf
    (obviously you have to verify the power dissipation and junction temperature as well)


  • administrators

    We recommend that you do not run water pumps that used brushed DC motors from the fan outputs. This is because the starting current for a brushed DC motor is usually many times the running current, and will probably exceed the 4.4A rated current of the bed mosfet.

    If your E1 Heat output is free then you can use that to drive the water pump; but then you must use an external flyback diode.



  • Ok I will remap a heater on my Duex2 board and use that. Thank you @dc42



  • @dc42 said in 12v Water Pump on a 24V System:

    We recommend that you do not run water pumps that used brushed DC motors from the fan outputs. This is because the starting current for a brushed DC motor is usually many times the running current, and will probably exceed the 4.4A rated current of the bed mosfet.

    If your E1 Heat output is free then you can use that to drive the water pump; but then you must use an external flyback diode.

    Maybe add that to the warning about adding diodes to brushed motors in the wiki for completeness? (And good catch!)


 

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