24 Volts Bed Heater Problem

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.

drmaestro

The bed heater works but immediately resets the duet, as the power supply cannot keep up with the 500 Watts request (it is a 350 Watts PSU). I ordered a 200 Watts bed heater now. I assume the circuit itself is ok, as if it was burn't I wouldn't be seeing any increase in the temperature.

As a side note, I removed the fan connectors, removed the crimps, connected them directly to the PSU to individually test them and they work, so it is probably some bad wiring by me creating the 24 volts fans not working problem.

I read the fan page on the wiki. As I understand, it is possible to either use all 5 volts fans (I don't have any), use all 24 volts fans (in that case I need 1 more 24 volts blower and a 24 volts large fan to cool the Duet board), use all 12 volts fans (in that case I'll need a buck converter, that I already have, and connect the +and - inputs of the converter to my 24 Volts PSU, and connect the positive output to V-fan jumper. I that case, all of the fans (PWM and always on) will be 12 volts. Or in my case, if I want to use 2 24 volts and 2 12 volts fans, I need to apply 24 volts to V-fan jumper (which means I can leave the jumper in place, as my PSU is 24 volts and V in will provide that 24 volts), however for the 12 volt fans I need to apply 12 volts from a buck converter, but the negative ends will go to the Fan - connectors. I assume I can use a single buck converter for supplying 2 12 Volts fans (the buck coverter can output 3 A, so it should be enough). My best option, until I have a all 24 Volts setup, seems to use the last option, which will require a minimal chang in wiring only.

Anything wrong with my understanding?

dc42

@drmaestro that is all correct.

drmaestro

@dc42 Thanks. I did the re-wiring and made a change to the config.g (the F2 fan was set to be controlled thermostatically, I removed it). All of the fans work as they should now. Thanks again everybody.

I'll now have to wait pateintly for the new bed heater. I hope my 350 w power supply will be enough. I am trying to make the calculations using the Wiki page:

The bed will be 200 Watts
The hotend is 50 Watts (I also have 40 Watts if I need to decrease the power usage)
I have 5 steppers. 2 Of them are Pololu steppers with threaded rods. They are 2.8 Volts, 1.7 A, so 4.8 Watts per motor. The extruder is 2.5 Volts, 1.2 A (3 Watts). The Y axis motor is 3.4 Volts, 1.7 A (5.8 Watts), The X axis is 2.8 Volts, 1.7 A (4.8 Watts). In total the steppers require 23-24 Watts. The wiki advises to add 50% to that number, so that's 36 Watts.
I have 2 blower fans (one 24 V, one 12V (soon to be replaced),, 1 hot end fan and one 8 cm fan for cooling Duet. The 8 cm fan is 12 Volts, 0.18 A (2.2 Watts), The 12 v blower is 0.09A (1.08 Watts), the 24 V blower is 0.06 A (1.44 Watts) and the 24 V Hotend fan is 0.08 A (1.92 Watts). In total, the fans require 6.65 Watts.
I have a 7 Inch Panel Due (3.5 Watts according to Wiki)
Duet itself 2 Watts according to Wiki.
BLTouch, not entirely sure but the web site talks about 5 Volts and a current of 15 mA to 300 mA (peak), so assuming the peak current, it should be around 1.5 Watts

That's my current configuration and in toal it is 299.65 Watts. I assume the 350 Watts power supply is adequate for this purpose.

Also, I plan on changing the part cooling fans with an air pump (the berd-air pump) in the future. The web site mentions the 24 Volts pump's rated current is 1200 mA, but then in the next line it mentions Current rating: 150 ma @ 24 v, so I can't really calculate the power requirement: ıs it 24x1.2A =28.8 Watts or 24x0.15=3.6 Watts? If it is the first, the 350 Watts power supply may be at it limits, if it is the second, then it isn't a problem. (the web site is https://the-makerhive.myshopify.com/products/berd-air-max?variant=33133668499591)

Edit: On AliExpress, there is a similar pump which talks about 12 Watts, so maybe that's the correct number and there may be a possibility to run it with the 350 Watts PSU