UPS & Form 2

Does anyone have any recommendations on a UPS to run alongside a Form 2?
Sometimes got power outages here, and while they’re not usually very long duration, it doesn’t matter how long they are to the printer…

thats what Id like to know as well.
I no nothing about power backups at all.

Form2 says it’s 65 Watts.

  1. Take the maximum time period you expect to be without power while printing, in hours.
  2. Multiply by 65 (probably, you’d be well advised to round that up some, to 70 or 75W).
  3. Buy a UPS with that many Watt-Hours of rated capacity.
  4. Plug Form2 in to UPS.
  5. Done.

If the UPS isn’t rated in Watt-Hours, get its maximum load rating (which will be in Watts) and run time at that maximum load (which will be in minutes, unless you plan to spend a lot of $) and figure out Watt-Hours.

Example: Select a UPS with a maximum output rating of 500W that can sustain its maximum output for 10 minutes. That means it can do 500W for 1/6th of an hour. So it can output 1/6th of 500W for 1 hour. That calculates out to 83.33 Watt-Hours of capacity (500/6=83.333). The Form2 draws 65W in operation, so it could run for 83.33/65=1.28 hours on this example UPS.

The usual suggestion is to factor the power usage as (in W) as 60% higher against the VA rating - which is why they slightly oddly list a VA rating and a W rating most of the time, where the W rating is about 50% of the VA rating. Mostly to do with not over-discharging the batteries.

Now, does anyone have suggestions on specific models or makes? The only ones I’ve used previously lived in 19" racks.

Forgive my ignorance as I still did not hook my Form 2 up yet, but since its WiFi I have the Form in a different room.
So will I need to have a separate UPS for my PC as well?

The Form1/1+ and the Form2 do not require a computer to be attached, you only need the computer to send the print file to the printer, after that the computer can be disconnected/turned off.

@ESpy the same models you bolt to 19 inch racks, you can use with the Form 2. I actually have an APC SmartUPS 1100 stored to use with the Form 2.

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True, but I’ve been trying to escape rackmount kit since switching careers.
I had been looking at APC’s smaller options.

Just go to BestBuy and get yourself something in the >1000VA range.

This one for instance is a CyberPower 1500VA UPS and rated to deliver a maximum 900W output for 2 minutes.

A Form2 draws 65Ws in operation so each hour it consumes 65 Watt-Hours of energy. The UPS’s 900W for 2 minutes is the same as 65W for 27 minutes (900/65*2). So for $159 you can have security and peace of mind against power losses of 27 minutes or less.

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Might be a costly trip for me - and I need 220VAC :wink:
Need to try and work out a cost/benefit against the worst-case power outage duration vs. the value of keeping the print going.

Head to your local neighborhood equivalent to BestBuy. Or check eBay/Amazon. They make 'em for 220V same as 120V, no real difference in cost vs. wattage. And the math is the same. Watts is Watts.

Rest assured that even “risk takers” like you, crazy enough to live where the power standard is 220V, are entitled to the same protections from arbitrary power loss that we 120V folks enjoy. Nowadays, thanks to the miracle of Global Commerce almost anyone the world over can enjoy an equal level of protection if they have a mailing address, an internet connection, and a credit card.


And it’s worth mentioning, the cost of the UPS is mostly proportional to the “hold up” time. Higher capacity costs more money. If you follow the logic of the math I did earlier, if you thought you only needed a few minutes of ride-through, you could get by with maybe 1/7th the capacity UPS. In my example the UPS was good for 1500W for 2 minutes. But a UPS that delivered 200W for 2 minutes would still be good for 200/65*2 = 6 minutes running a F2, and probably if you could even find one this small its cost would be less than a replacement resin tank for your printer…

Woohoo, I’m a risk-taker :smiley: Not quite enough of a risk-taker to stick my fingers in even a 110VAC outlet though, there are limits. It did occur to me that the PSU on the F2 is autoswitching, but the input to the UPS still needs to be 220VAC. +/-

Realistically I probably need about 10mins-15mins of cover (enough to cover both the normal outage and the time to reset the breakers), so I’ll pick over models based on that. I tend to go through manufacturers’ sites for the detail specs rather than 3rd party sales sites - personal preference only.

The full-load times are worst case. Light loads can usually get about double the watt-hours from the UPS. APC has calculators or run-time charts for their UPS’s.
Here’s one I pulled of basic models from their UK site:

If you really want long run time, their highest Back-UPS Pro has an external battery pack and should run a 65W load for 4 or 5 hours.

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It’s probably sensible to employ a light duty UPS and pause your 3D printer until power is restored. Press the front panel switch once to request a pause: the printer will finish its current layer, then raise the platform and move all its equipment to safe positions before stopping.

That offers two additional benefits in the event of an extended outage:

  1. Pausing conserves energy, so your UPS will last longer if the outage last longer than you anticipated.

  2. If a prolonged power outage does exhaust your UPS, you’ll still be able to remove the print, build platform, and resin tank from the machine even without power. (By comparison, an un-paused machine is likely to trap the platform inside the resin tank.)


Sounds worthwhile on both counts. A power outage mid-layer write wouldn’t be hugely helpful, and your point of being able to remove things cleanly seems good - although I’d rather assumed the power up sequence took the build platform to home first, so you can pull things when the power’s back.

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