Well redo the math my dear WATTson but this time include OHMs law and remember that a heater is a resistor which has a fixed resistance (theoretically).
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Well, that someone is neither you (@josephlreyes) nor @rbennett, I am afraid. 
You’d be right if the electrical load would be somehow regulated to always use the same power regardless of the supplied voltage. Such loads exist. A simple heatbed, supplied directly from the mains, is not one if those.
Any simple electrical heating element is basically a resistor, be in in an electric heating in your house, a haidryer or a 3D printer heatbed. In case of the X1C I can even tell you its approximate value: at 230V it uses around 1kW, according to R=U²/P this results in roughly 53 Ohm. Hence, the current I=U/R is around 4.3A.
Now you connect the same heatbed to 110V in the US. The unchanged resistance of 53 Ohm results in a current I=U/R of 2.1A. This again gives you a power P=U*I of about 230W, a little less than a quarter of the power you get on 230V.
This conforms to the general rule that an increase of voltage by factor x results in an increase of power by x² with a constant resistance. If you want to try this in a more practical way: get yourself a European hairdryer and connect it to a US socket providing 110V. The result will be quite disappointing and will certainly not get your hair dry in due time. A 2,000W beast will not even produce 500W.
A bit more spectacular is the opposite case: connect a 2,000W hairdryer from the US to a European 230V outlet and you will get an incredible 8,700W. The only issue (besides some burnt hair) will be a very, very short life of that poor appliance… 
By the way, there are some hairdryers and other heating devices on the market which can be switched to either 110 or 230V. For such loads this does not require any electronics but just a simple mechanical switch. In fact, the heating element is just split into two parts: for use with 230V, those two halves are connected in series (doubling the resistance of a single one), for 110V in parallel (cutting single resistance in half). This means that with the 110V setting the resistance is reduced to a quarter of that at the 230V setting. According to P=U²/R, half the voltage and a quarter of the resistance results in the same power. Mission accomplished. Whenever you find a mechanical switch for selecting between 110 and 230V on any appliance of power supply, this is the principle behind it.
Finally, the above calculations are not entirely accurate as the maximum specified power draw of a X1C on 220V (yes, they specify it for 220 and not for the more common 230V) of 1,000W is not entirely used by the heatbed but also includes electronics, fans, stepper motors, and toolhead heating (which all are supplied by regulated low voltage and therefore use the same power regardless of grid voltage). I would estimate the maximum power of the heatbed alone to be around 850W. If you do the math once again with this value on 220V, you will get around 210W on 110V. Add the remaining 150W for the rest of the system and you get 1,000W on 220V and 360W on 110V. And now have a look into the official specs:
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I’m in Canada, so ~120-volt supply here. Ran a 2-hour 31-minute print to test this to see what mine does when plugged into a kill-a-watt clone. This was a PLA print at 220 C / 55 C. Peak power was 295.3 watts. The entire print used 0.219 kWh, and since it ran for 2.5167 hours, this means it averages 87.02 watts for a job like that. The job cost 2.4 cents at the $0.1097/kWh BC Hydro charges. Sitting idle, the meter is alternating between 6.3 and 6.4 watts. Idling at 6.35 watts for a year would ring up $6.10 on the electric bill. I’ll eat that to gain the convenience of starting a print anytime I want if I’m out somewhere. “Oh, you want one of them widgets? It’ll be ready when I get home.” 
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Just to update with my own data using an X1c, Power-Mate Lite and a 230V grid voltage.
Standby with screen on, light on: 10.77W average ± 0.01W ranging from 10.7-10.95Wm
Standby with screen off, light on: 9.28W average ± 0.07W ranging from 9.18-9.69W
Standby with screen off, light off: 7.95W average ± 0.08W ranging from 7.87-8.44W
The rest are measured in isolation, with screen & light on:
Heating bed 17-70ºC: time taken 1m03s, 9.37-1044.4W, 765.71W average (± 5.71W), as others have observed it uses more power when cold; 0.0134kWh used
Heat bed maintaining 70ºC for 15m3s, 17ºC ambient, door open/lid ajar: 80.13W average (± 0.4W), 53.6-134.15W
Nozzle heating 18-240ºC: 0m51s, 35.29W average ± 7.06W, range 9.42-58.23W. 0.0005kWh used
Maintain nozzle 240ºC 10m (avoided significant timeout cooldown): 18.6W ± 0.6W, range 9.99-41.0W, 0.0031kWh used
Nozzle cooldown until fan turns off: 4m44s, 10.14W average ± 1.27W, range 9.31-18.99W, 0.0008kWh used
Auxiliary fan at 100%: 21.13W average ± 0.01W, range 20.93-21.41W, 90% ~16.9W, 80% ~14.7W, 70% ~13.15W, 60% ~12.25W, 50% ~11.2W
Chamber fan at 100%: 16.51W average ± 0.01W, range 16.19-17.07W, 90% ~14.2W, 80% ~12.8W, 70% ~11.65W, 60% ~10.85W, 50% ~10.3W
Part fan at 100%: 12.47W average ± 0.01W, 90% ~11.4W, 60% ~9.9W
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The wattage is defined with respect to applied voltage. For eg. when I say 1000W, the device operating voltage is also defined, say 230V. Under this circumstances I = P/V, = 4 amp approx. Load resistance R = 230/4 = 55 ohms approx. Load is fixed, ie 55 ohms. Hence with lower voltage ie 110v , the current will be V/R = I, ie 110/55 = 2. A.
Now Power consumed will be P = VxI = 110*2= 220 W.
Power specs and power consumption comparisons with various materials are in the Wiki:
https://wiki.bambulab.com/en/general/power-consumption
I have both 110 and 220 outlets in my shop, so switching X1C voltage is as simple as changing the cord. For a similar forum discussion I ran a quick test:
… and that was the last time I operated my X1C on 110V.
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I just found this thread and it’s interesting. I need to think about this some more because it seems odd that changing the line voltage would have such an effect.
The power supply should be all that is seeing 220V while the printer itself should just see whatever the power supply output voltage is. Cutting current in half is good though since you reduce resistance losses in the wiring to the printer power supply.
Cartridge and film heaters are resistive heaters. If you power them directly from the line you would obviously see big heating differences based on the line voltage, I’m not so sure I want them banging that hard. Running them at lower line voltage will be gentler on everything.
It’s a puzzle.
I have an 900VA UPS with smart plugs on output and the data I’ve collected is:
- when in stand-by mode it stays between 7.9W and 8,5W with chamber lamp on, or between 6.7W and 7.2W with chamber lamp off
- when starting a print with 2 AMS attached it gets above 900W for about 20 second when heating the bed. But its consumption never exceeds 950W at which point my UPS should start playing an alarm.
- during a print the consumption varies but it’s slighly above 130W
I should add that the higher wattage using 220V had confused me at first.
My only previous experience with dual voltage devices was all with motorized woodworking machines. Operating a motor with single phase 220 instead of 110 cuts the amperage by half, and power consumption stays basically the same. Higher voltage, lower current means a thinner (less expensive) gauge wire can be used without excessive voltage drop on long runs.
The difference is that changing the motor voltage requires rewiring the two sets of field coils, so it is really a different load. The coils are wired in parallel for 110V and in series for 220V. If a coil has resistance (impedance) R, two coils in parallel have a total resistance of R/2, but wired in series the resistance is 2R (four times as much). Voltage doubles, but power usage stays the same.
Our printers have the same resistance for both voltages, so power consumption goes up by the square of the voltage.
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Except for the A1 mini, the resistive heat beds on the Bambu printers all work on 110V or 220V line voltage, which is switched on/off to maintain the set temperature.
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Which would explain the faster heating as I mentioned. I think I’ll keep my printer at 120V. Less voltage is less current in that case - not more - so more gentle on the heaters. I’ve worked with cartridge heaters and no need to deal with changing heaters more often than needed, IMO.
The nice thing about 110v is that you can raise the heated bed up to 120C, which works great for printing ABS on garolite. For mysterious reasons, on the X1 220v only allows you to get at most 110C.
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Bambu lab Nick explains it in this link. From the Kickstarter days.
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^^^Interesting! That solves the mystery. It sounds as though it was the result of a last minute discovery made during final testing. I get the sense that if they had known earlier they might have tweaked the design to avoid the issue, but it’s understandable they wanted to get the product out the door, so they took the conservative approach. The alternative would have slipped the schedule, so it makes perfect sense. I’m just lucky to be on 110v AC. 
Of course, if someone on 220vAC really wants/needs that 120C, they should be able to get a transformer to 110V AC fairly easily, and then they’d have it too. Given the wattage involved (350W max according to the spec sheet), I imagine a suitable transformer wouldn’t be very expensive.
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I have seen some similiar thing with LED things… I am not an electrician, but in my case (not 3D printer just some LED tool) was flashing sometimes, or sontinously turned on but very dimmed…
And what i suggest to try to flip the plug in the connector with 180 degree if you have the EU socket. Somehow in my case the issue was the N (neutral wire) somehow pushed some electricity to my LED tool. (sorry if it sound bullshit, but in my case somehow worked with my plug)
@zizzo81 Sorry for resurrecting an old post, but I thought that it’s interesting that your UPS isn’t tripping out. The average PF for the X1C is 0.54, which means at a real power measurement of 900W you will be pulling an apparent power of 1666VA through your UPS. I was really surprised to see such a low PF on a consumer product.
(S(VA) = P(W) / PF. An UPS is almost always rated in VA because they don’t know if you’re connecting a inductive, capacitive, or neutral load to it.)
Your print average of 130W (240VA) is a little higher than the Bambu PLA specification of 105W. At least it’s only overloading for a short period, but it still may shorten your UPS’ lifespan.
Hi don’t worry, happy to see some interest. I actually have three kind of UPS at home (I own a lot of computers in my studio and I need protection for each of them) which last year replaced two older models. Unfortunately my experience with UPS is that you can also replace the batteries by yourself (did it a lot of times) but they’re going to give you problems. e. g. last year I changed the batteries on two of them, the first time I had an electric shock they both did not keep my PC alive, so I changed them both. I regularly change them because in either way they will not last more than 3 years.
Keep in mind that some data I’ve collected could differ also because the smart plugs are not that precise on measurement.
Also I discovered that pre-heating the bed before launching the actual print (and now I have 4 AMS units connected and connected an additional series of LEDs around my top riser, connected a BLLED unit and a chamber heater, all things that have risen power consumption) by getting to steps of temperature avoids the alarm being triggered. I first set 30°C and wait it to arrive at that temperature, then I set 40°C and wait for it to reach the new goal, after that I simply put the destination temperature even 100°C when printing ASA
On cold mornings when I do that operation is beeps for the first 5/6 seconds when moving to 19°C/22°C to 30°C but then stops.
So I imagine - but I’m not good as you are in electric calculations, I just report what the tools I have are telling me - that the peak raising the alarm is the initial one and doing this way lowers the absorption curve.