24 Volts Bed Heater Problem
-
@jens55 Interestingly it isn't. If I try to increase the neated bed temperature it starts to rise 1-2 degrees but then resets. So I think it isn't blown (I am not doing it anymore of course).
-
@drmaestro said in 24 Volts Bed Heater Problem:
@joel I may have to change the heating pad instead, as I don't have enough free space for an additional power supply. What is the highest wattage that Duet can directly operate?
The switch the duet uses says 18A, you probably want to be something less than that to have some margin. If you say 15A, that would be a 360 Watt heater.
Keep in mind you power supply has to do the bed heater, the nozzle heater, the fans, and the board. The fans and the board are small compared to the nozzle and bed heaters.
Add the bed wattage, the nozzle heater wattage, add 50 watts for the duet and fans, multiply that answer by 1.2 and that's the size power supply you want.
Opps - forgot the steppers, need to add those in too. You want to assume everything is running at the same time
-
@joel I should probably have gone with this https://www.aliexpress.com/item/32327554677.html?spm=2114.12010612.8148356.10.3dd87d80abwHH4 insteatd of this https://www.aliexpress.com/item/2050749273.html?spm=2114.12010612.8148356.12.3dd87d80abwHH4
-
@drmaestro, most switching power supply are good at sensing output power and shut down so in your case you doubly got lucky (go out and buy a lotto ticket)
What I would do is to disconnect the heat pad and the 12V fan and see what works and doesn't work.
24V is good but you'd need a larger supply and run the heat pad via a relay as the Duet is not capable of powering it directly. -
Actually a 24V supply is better for trying to use a higher wattage heater, less current required for the same power.
-
@drmaestro, 500 watts for a 200x200 mm is pretty high. Is the bed only 200x200 or are you improvising with a smaller pad?
-
@drmaestro said in 24 Volts Bed Heater Problem:
@joel I should probably have gone with this https://www.aliexpress.com/item/32327554677.html?spm=2114.12010612.8148356.10.3dd87d80abwHH4 insteatd of this https://www.aliexpress.com/item/2050749273.html?spm=2114.12010612.8148356.12.3dd87d80abwHH4
yes, 200W is more appropriate for that bed size anyway.
-
I would say that 200W is good if your build plate is 200x200. If your build plate is 300x300, I would stick with the 500W heat pad and increase the size of the power supply and run the heater via a relay. (switch to bang/bang operation for a relay)
-
@joel said in 24 Volts Bed Heater Problem:
@drmaestro said in 24 Volts Bed Heater Problem:
@joel I should probably have gone with this https://www.aliexpress.com/item/32327554677.html?spm=2114.12010612.8148356.10.3dd87d80abwHH4 insteatd of this https://www.aliexpress.com/item/2050749273.html?spm=2114.12010612.8148356.12.3dd87d80abwHH4
yes, 200W is more appropriate for that bed size anyway.
What size ( wattage ) nozzle heater are you using?
-
If you got the 200W bed heater and if your nozzle heater is the standard 40 Watt, say that leaves you with 60W for everything else ( you probably don't want to run right to 350Watts of the supply. 60W is 2.5 Amps at 24V, you still might be cutting it close with the duet, steppers, and fans, but you could push that margin if you want. I would also step up to a 480W supply.
-
@joel I have a 50 watts hot-end heater
-
@joel I haven't been able to find one, I'll search for it.
-
@jens55 I have a 220x220 bed.
-
OK, 10W more than my guess. I think you would be better off with a bigger power supply, you could try the one you have and if it runs, run it till it quits.
With a 200W bed heater, the duet will be fine without a relay.
-
I don't know where you are, but I saw some 480 Watt on Amazon.
-
@joel I have tried to run the hotend fan and also the cooling fan (the 24 volts one) using the always on fan connectors and they aren't working. Maybe there is a problem with the fans themselves or the wiring (I use a 12 volts always on fan for cooling the Duet board and it is working without a problem on the always on connectors).
-
For fans, I think you can power 5V fans from the duet, other than that, the fans have to match your supply voltage, so you will need 24V fans. You also have to set the fan voltage source on the duet
-
-
For the hot end fan, I don't think it comes on until a certain temperature is reached, I think set in the config file. For cooling fan, are you talking about the part cooler?
Are you starting with the same config file from the previous setup?
-
Are you aware that most fans are polarity sensitive? They can also be destroyed by wrong polarity so it's possible that you killed them.
I would suggest that you stop using the 12V fan until you got all your other issues sorted out and then read up on how to connect it to a 24V source - it is not as straight forward as you think.
