I had problems with my UPS shutting off just after power-on. I contacted tech support and after they asked me which devices are connected to UPS, they told me not to connect 3D printers to UPS.They said that devices with motors can’t be connected to UPS.
I have had no problem.
Mine I changed the battery for a 100A car battery and have my 3D printer connected to it all the time.
The power went off during a big print and the battery lasted for the full four hours needed to finish.
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It’s complicated!
The real answer is probably simply that your 3D printer draws too much current.
Their “devices with motors” advice doesn’t actually apply to a 3D printer. But to explain why, I need to explain a little more.
Cheap UPSes (most of them!) generate square waves which they meretriciously call “modified sine wave” — the “sine wave” part of that is true only in theoretical sense, since every waveform including a square wave can be created by the composition of multiple sine waves, but that doesn’t give you the value of being composed of a single 60Hz sine wave like the electricity you get from a wall outlet.
The motors they are thinking of are synchronous AC motors. Those can be damaged by, or damage, a “modified sine wave” square wave UPS.
The reason that a square wave is fine for lots of things is that both switched-mode power supplies and resistive loads handle square wave just fine. In fact, they don’t even care whether the electricity is AC or DC! Most switched-mode power supplies can run off DC that is within their input range.
3D printers have switched-mode power supplies, and the motors aren’t AC motors. Instead, you have a motor controller that modulates the DC power output from the power supply to turn the motor. This means that the reason not to hook motors to cheap UPSes doesn’t apply here. But I wouldn’t expect UPS support people to know that. They just have a script that says “motors = bad”.
It’s more likely that when you turn on all the heaters, you are simply drawing too much power for your particular UPS.
Please feel free to share details on your printer and UPS and we can help validate that.
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