Which 24v power supply ?

  • Hi all this is my 1st post so forgive me if it's been covered already. I'm building my 1st printer , iv opted for a corexy design with nema23 motors , going to use the duet2 wifi with the 7" LCD , I want to use a 24v power supply but don't know which one would be best suited for my needs , as in wattage and amps .
    Here is a list of components that I'd like to run
    3x NEMA 23 2.8A
    2x NEMA 17 high torque (not ordered yet)
    1x e3d volcano hotend (maybe upgrade to duel extruder later on)
    2 X cold end fans
    2 X 5015 blower cooling fans
    Possibly a BL touch ....not sure
    6 X end stops ....may opt for optical
    Duet 2 WiFi with 7" screen

    I'm not running a heated bed from the supply

    Is it just a case of adding up the amps and + 10% for good measure? I don't know hence why I'm posting .
    Cheers .

  • I have a similar setup and I bought a Meanwell SE-600-24 but I haven't tested it yet. It has 600W / 25A output. The input is either 115 or 230VAC, selected with a switch and the output voltage can be adjusted. Maybe it is too much for your setup but you never know what you want to add in the future.
    My opinion is to not buy a noname power supply.

    Meanwell SE-600-24

  • Moderator

  • @wizard If you calculate to need less than 200 W, I would recommend the Mean Well LRS-200-24, which is fanless and silent.

  • I have been using Meanwell supplies with no issues.


  • @fcwilt said in Which 24v power supply ?:

    I have been using Meanwell supplies with no issues.


    Just make sure you don't buy a cheap Meanwell knock-off 🙂

  • @whosrdaddy said in Which 24v power supply ?:

    @fcwilt said in Which 24v power supply ?:

    I have been using Meanwell supplies with no issues.


    Just make sure you don't buy a cheap Meanwell knock-off 🙂

    Difficult to spot the knock-offs as they are all made in China anyway - that is if you class Taiwan as being part of China (which the Chinese would like us all to do). ☺ From their web site ................"production bases in New Taipei City (Taiwan) and Tianhe District and Huadu District in Guangzhou, Suzhou City in China"

  • Moderator

    Best way to avoid a knock-off is to purchase from a reputable supplier like Digi-key or Mouser.

  • Ok, so how many amps would be needed? Safe to assume 200-600 watts will be enough so......say a 20amp ? Would it be enough as well as give some growing room?

  • @wizard You use Nema 23, which is overkill normally. But maybe you build a monster 3d printer... If the steppers use 2 A maximum, this is 50 W for each stepper, plus 30 to 50 W for each hotend, plus something for fans and controller. So 200 to 600 watts is correct. The steppers and hotends do not work at the same time, so your watt is lower than the maximum, but it's a risk. I would use the highter watt end in your case.

    Be aware to use the correct, thick enough wires at the PSU and good connectors which do not slip.

  • @joergs5 the build area will be 500x500x1000mm (z axis is more like 800mm when finished) each NEMA 23 is rated at 2.8A so 2.5A is roughly where I want to be running them at 🙂

  • @wizard Be aware of the upper stepper controller current limit of Duet (I am not sure about the exact limit, you will need a good fan anyway).
    I build a similar dimension, but Z not so high.

  • Once the duet WiFi board is delivered I will be adding heat sinks and fans to keep it nice and cool , just need to figure out what kind of PSU il be needing to power it all lol

  • A Meanwell LRS-xxx-24 is a good choice. For practical purposes, heaters are the only loads that matter all that much. Motors use less power than you might think. If they are 2.5A steppers, they don’t actually use 24v * 2.5A = 60w like you might expect, because the stepper driver is using PWM to regulate current and only energizes the motor coil a small percentage of the time.

    The worst-case PSU load for a stepper occurs when both coils are energized to sqrt(2)/2 = 71% of specified current at a half step position. Then the total coil current is 141% of your specified current. However, the PWM is only on some of the time for each motor coil, so the actual total power provided by the PSU across all the motors is a lot lower. For a good approximation, you can multiply the motor’s rated voltage from the datasheet (or rated current * coil resistance) by 141% of specified current. That’s your motor power draw from the PSU if the motor stops at a half step without idle current reduction.

    So, for a 2.4A motor current setting (Duet 2 max) on a motor with say a 4V rated voltage, your max power draw per motor is
    2.4A * sqrt(2) * 4V = 13.5 Watts.
    Multiply that times the number of motors, add heater wattage at max power, and then add say 40W for the Duet and PanelDue and fans and miscellaneous.

  • In my own calculations, when I upgraded my Wanhao D5S Mini, I simply ensured I have a good overhead for the Stepper drivers and it simply works.

    On my setup I am running the DuetWifi, 4x Nema17 stepper motors (at just over 1A per phase), 5" PanelDue, 200x300 heatbed (estimated wattage of 160W @ 24V), 30W E3Dv6 a bunch of fans (including blowers etc) a RaspberryPi Zero W with a camera and an LED strip (as well as obviously the small current items). All of this is powered through a single Meanwell LRS-350-24 power supply - and based on my power monitor, the unit is not close to being overloaded, even with all heaters on and the motors and fans running at full speed (last time I checked, it was near 250W).

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