Heated bed with more than 18A



  • Hello,

    i want to use the anycubic chiron heated bed with the duet 2 wifi.

    The problem is, it has 500W and at 24V that is around 21A.
    What happens when i connect it to the board?
    Will the board limit the current at 18A or does the heated bed draw the 21A and overload the board and brake something?

    What options do i have, to use this combo?
    Or maybe somebody knows a 400x400 hetaed bed that does not exceed the 18A limit at 24V?

    Thans in advance.

    Regards



  • you can get an external mosfet that is rated for that current. Something like this https://www.aliexpress.com/item/32756137315.html
    you connect that mosfet directly to the power supply so that the current does not get passed through the duet. the mosfet gets connected to the duet hotbed output and uses that on/off signal to turn the power to the bed on and off.



  • For that kind of power it's best to go with a line powered heater. It will require much less current so no need for heavy, inflexible cables. You won't need a super big power supply because a heater doesn't care if you give it DC or AC. I replaced a 450W 24V heater (mistake to install it in the first place) with a line powered heater and replaced the industrial power supply that sounded like a vacuum cleaner with a fanless 24V 8A supply (overkill at that current rating). Huge improvement!

    Keenovo makes a lot of heaters in useful sizes, and they will make a custom one for you, too, if you need it.



  • I already have a phoenix contact 24V 40A PSU that makes no noise.
    And i dont want to use 230V AC.
    If it's as simple as connecting a mosfet between the Duet Board and the heatbed, i'll go that route.



  • I don't have the chiron. I only want to use the printbed of that printer together with the duet 2 wifi in the idex printer that i am going to build.



  • @user13 said in Heated bed with more than 18A:

    If it's as simple as connecting a mosfet between the Duet Board and the heatbed, i'll go that route.

    It is, and if you have the power supply and some beefy wire its hardly any difference if you go 24v or mains powered. Heck you might actually end up running the PSU with a higher efficiency in that case. If the mosfet module runs hot you could always find a mosfet with lower Rds(on) and replace it. I'm sure you can do better than most chinese ready to go modules

    OT; do you know who Phoenix use as OEM for their power supplies? And I hope you got a sweet deal on that 40A PSU, I've got some freebies 5A QuintPower from Phoenix but they were like 2-300 a pop



  • I am using a very similar setup as you described. The heated bed is a 320*320 24V that uses ~19-20A on initial powerup and then slightly less as it gets warmer. Like you I already had a powerful 24V supply and would rather not use mains wiring for the heated bed.

    This is the mosfet board I've been using to bypass the Duet:
    https://www.amazon.com/HiLetgo-Printer-Accessories-Expansion-Replacement/dp/B07C7RQ4C6/ref=sr_1_7?keywords=3d+printer+mosfet&qid=1564695675&s=gateway&sr=8-7

    It does not even get warm during heatup, and I've had no issues with it, I just drive the control signal from the Duet heated bed output. Let me know if you have any questions about the setup.

    Edit: Just wanted to add that I use 12AWG wrire from PSU>Mosfet and 12AWG Silicon high temp wire from mosfet to heater.



  • Thanks to all for your help.
    The anycubic heatbed comes already with with wires attached.
    But i'll keep that in mind and check the diameter.