24 Volts Bed Heater Problem

drmaestro

@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

jens55

@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.

Joel

Actually a 24V supply is better for trying to use a higher wattage heater, less current required for the same power.

jens55

@drmaestro, 500 watts for a 200x200 mm is pretty high. Is the bed only 200x200 or are you improvising with a smaller pad?

Joel

@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.

jens55

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

@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?

Joel

@drmaestro

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.

drmaestro

@joel I have a 50 watts hot-end heater

drmaestro

@joel I haven't been able to find one, I'll search for it.

drmaestro

@jens55 I have a 220x220 bed.

Joel

@drmaestro

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.

Joel

@drmaestro

I don't know where you are, but I saw some 480 Watt on Amazon.

drmaestro

@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).

Joel

@drmaestro

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

Phaedrux

https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater
https://duet3d.dozuki.com/Wiki/Choosing_the_power_supply
https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans
and for good measure
https://duet3d.dozuki.com/Wiki/FireSafety

Joel

@drmaestro

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?

jens55

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.

drmaestro

@joel Yes, normally it starts at around 45-50 degrees but I tried to heat it to 80 degrees and it didn't start.

Cooling fan = part cooler

I am using almost the same config, except I added the second 12 volts fan as a cooling fan to tool one (orisignally both of my fans where connected to a single fan output, now that one of them is 12 volts, I had to use a second fan output).

Either way, none of the fans (part cooling and hotend) are working, even if they are on always on connector, so there definitely is a problem on the fans or the wiring....

@jens55 I am aware of the polarity issue and was careful to wire the right polarity.

dc42

@drmaestro said in 24 Volts Bed Heater Problem:

@jens55 Is there a possibility that I might have blown a fuse while trying to use the bed?

Yes, if the bed heater doesn't work at all now but the rest of the Duet does. The bed heater fuse on the Duet is rated at 15A. It would likely carry 20A for several minutes before failing. You can substitute a 20A fuse at your own risk.