MakerGear Forum

I found an old thread that said all heaters full bore was 300W, and idle was 20W. What can I reasonably expect for an already-at-temp printer, without an enclosure, at both PLA & ABS temperatures? I'm guessing 120 and 200W respectively.

insta wrote:an already-at-temp printer

A Kill-a-Watt has trouble reporting the average power for PWM loads like the extruder heater and rapidly switching loads like the platform heater, but here are some results for my hot-rodded M2:

Idle:

• 18 W with extruder + electronics fans on
• 13 W with fans off: S108 S0

The V4 extruder heater adds 45 W at 100% duty cycle (total 63 W). It runs at 40% duty cycle to maintain 250 °C and adds 17 W (total 35 W). Pronterface gives you the extruder duty cycle (it's the mysterious @:nn value in the status line) as an integer from 0 through 127, so you can compute the average power as 45 x nn/127; you're on your own with S3D.

The hotrod platform I'm using dissipates 315 W (!) at room temperature and 275 W at 90 °C. The firmware controls the platform temperature in bang-bang mode, so the total M2 dissipation slams between 50-ish W and 330-ish W as the platform heater cycles. There's no "duty cycle" in that mode; you'd have to measure it with a stopwatch.

The original M2 platform dissipated something like 120 W, so your printers will alternate between 50-ish and 170-ish W.

I'd figure an average power of 250 W for my M2 and maybe 150 W for a stock M2, which should be close enough for cost estimating. With power at $0.17/kW·h, that's $0.043/h and $0.025/h, respectively... [grin]

It's not for cost estimation, it's for UPS sizing And what the hell the fans draw 5 watts?

Those numbers are a good starting point though, kind of surprised the bed still draws so much at temp.

insta wrote:it's for UPS sizing

In that case, you want one big enough to handle the full load at 100% duty cycle for a while, because otherwise it'll trip out during startup. Especially if you're buying a single UPS for all your printers, remember that nothing exceeds like excess!

An old 500 W Belkin saves my bacon during occasional glitches...

the fans draw 5 watts?

The dataplate says 24 V at 90 mA = 2.2 W, so, yeah, 5 W for a pair is as close as it gets:
http://softsolder.com/2015/03/12/makerg ... 24-v-fans/

kind of surprised the bed still draws so much at temp.

This one has a PCB heater with copper's big temperature coefficient, but (I think) silicone stick-on heaters use (something like) nichrome with maybe 10% of copper's tempco: they should draw nearly the same power at any useful temperature.

ednisley wrote:

insta wrote:it's for UPS sizing

In that case, you want one big enough to handle the full load at 100% duty cycle for a while, because otherwise it'll trip out during startup. Especially if you're buying a single UPS for all your printers, remember that nothing exceeds like excess!

An old 500 W Belkin saves my bacon during occasional glitches...

Well, this is for 4-5 printers. I can't imagine I'd be like "POWERS OUT TIME TO FIRE UP 5 PRINTERS AT ONCE", but if the power drops while most are running will a 900-1100W unit keep them running? I'd be putting a pair of deep cycle marine batteries on it rather than the little 7Ah cells they come with.

Power seems pretty stable at my office, but it will wait for me to have every printer going at once before some loon crashes into a power pole just to jack with me.

Are these 24V or 19V/12V units? If the latter, you may want to run the HBP PSUs from a different power source - the HBP is far less susceptible to brief power outages, and could probably maintain printing temperature for at least two minutes without power. Actually, if you wanted to get fancy and complicated, with 24V units you could rewire everything so that one 24V PSU powers two or three printer's motors and hotend/fans, and another 24V PSU powers two printer's HBPs... That's getting into Nisley territory, though X)

One thing you may also want to keep in mind - no power supply is 100% efficient. The MeanWell we use for the 24V M2 is rated at 86% efficiency, so if the printer is consuming 200W from the PSU, expect the PSU to be consuming ~230W from the AC source (assuming all my math and logic is in order - it's a bit hot today...). A Kill-A-Watt will reflect the (in)efficiency losses, but just calculating from what the components are drawing will not.

insta wrote:if the power drops while most are running will a 900-1100W unit keep them running?

Each one will draw 170-ish W with the platform heater running, so five together will be 850-ish W. A kilowatt UPS should do the trick, but remember that you want a kilowatt average, rather than peak, because the platforms are drawing power for relatively long times and they most assuredly will all go on at the same time.

Also, UPS manufacturers tout VA (volt·amp) rather than W (watt) in the big print, but the power bricks do a good job of power factor correction, so size the UPS based on the small-print wattage number.

putting a pair of deep cycle marine batteries on it rather than the little 7Ah cells they come with.

That won't work the way you expect, because UPS power transistors & heatsinks are sized to handle exactly as much energy as the internal batteries store. If you increase the battery capacity, the power transistors will burn out.

The heatsinks, at least in one UPS in my collection, are actual sinks: featureless aluminum blocks designed to absorb waste heat without any cooling airflow. The heatsink (and transistor) temperature rises as the UPS runs, but the battery capacity runs out and the UPS shuts down before the junctions overheat!

Fortunately, the guys who commented on my blog post proposing exactly the same thing smartened me up:
http://softsolder.com/2011/07/22/mge-el ... rangement/



Also, plan to replace the batteries every three years or so; they go bad without warning.

it will wait for me to have every printer going at once

Look on the bright side: the printers will have less trouble keeping the platforms hot after the air conditioning goes out... [grin]

Not that a UPS will give you more than a few tens of minutes more time, but that's more than enough for nearly all power glitches around here.

Josh wrote:Are these 24V or 19V/12V units? If the latter, you may want to run the HBP PSUs from a different power source - the HBP is far less susceptible to brief power outages, and could probably maintain printing temperature for at least two minutes without power. Actually, if you wanted to get fancy and complicated, with 24V units you could rewire everything so that one 24V PSU powers two or three printer's motors and hotend/fans, and another 24V PSU powers two printer's HBPs... That's getting into Nisley territory, though X)

One thing you may also want to keep in mind - no power supply is 100% efficient. The MeanWell we use for the 24V M2 is rated at 86% efficiency, so if the printer is consuming 200W from the PSU, expect the PSU to be consuming ~230W from the AC source (assuming all my math and logic is in order - it's a bit hot today...). A Kill-A-Watt will reflect the (in)efficiency losses, but just calculating from what the components are drawing will not.

First time my franken-ups setup fails me all the M2s (every machine in the room is 24v, from printers to mills) is getting wired to a big fat bus-bar over to a palette of batteries run by a single 2000 watt 24v supply.

sounds like you need to purchase one of my prime power military diesel generators..lol

Im just going to leave this here...

http://www.teslamotors.com/powerwall