Wattage rating for 24v power supply for smoothie

I am in the very early stages of converting one of my printers to smoothie (it currently used RAMPS) and at the same time am considering upping the PSU from 12V to 24V. I have been successfully running the printer using a 12V30A PSU, but I don't think I'm using anywhere near that capacity. I just have the usual 4 steppers for axes, 1 for extruder, one heated bed and one ESD v6 extruder.

The documentation I find for smoothie recommends the PSU have capacity of 17-20 amps, but it doesn't say at which voltage. If I look at the 24V PSUs, I can get up to 15A for a price comparable to what I paid for the 12V30A, but if I go over 15 Amps, the price doubles or more. So I guess the question boils down to how much amperage capacity do I need at 24v versus 12V. It would seem to me that it should be 1/2 of the amerage, but I'm not an electrical engineer.

Or maybe I should just stay at 12V .....

Thanks

If you swap all 12v components for 24v components the current should halve.

If you dont....
heated beds @12v take about 11amps the same bed at @24v will take 22amps so its it vital you get a new bed or plan for 22amps,

everything else @12v is under 5amp.. the largest load being the hotend... about 3 amps. and 6 amp @24v. (will most likely just die)


If you swap for 24v parts heated bed drops to 5.5amps and hotend to 1.5amps. + rest 2ish amps (presuming same wattage) so yes a 15amp 24v is fine

I was planning on swapping out the fans and the extruder heat cartridge for 24 volt versions, and the bed has an alternate connection configuration for 24 volts. At first glance, this would tell me that the 15 amp 24v PSU is fine, except that I would guess that the bed draw does not halve. It probably will continue to draw 11 amps at 24 volts which won't leave enough for the other components. Maybe the answer is 2 PSU's with one being dedicated to the bed.

Quote
jbernardis
I was planning on swapping out the fans and the extruder heat cartridge for 24 volt versions, and the bed has an alternate connection configuration for 24 volts. At first glance, this would tell me that the 15 amp 24v PSU is fine, except that I would guess that the bed draw does not halve. It probably will continue to draw 11 amps at 24 volts which won't leave enough for the other components.

No, if it's a dual voltage bed then the current draw will halve when you rewire it for 24V and use 24V.

If you measure the resistance of the bed, you can calculate its current draw.

A 24V 15A PSU is almost certainly enough.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].