Printing without a connection to Preform

I am considering getting a UPS for my form 2. I just want to put the printer on the UPS, not my computer system. Once a print starts, will losing the connection to Preform be a problem if the computer loses power?

And should I go with real a sinewave UPS or modified sinewave?

You don’t need to be connected to a computer to print. The job information is stored on the printer.

For any electronic devices a true sine wave UPS is always preferred.

I have mine plugged into a CyberPower CP1500PFCLCD PFC Sinewave UPS 1500VA 900W. It has actually saved 2 prints from power failures so far!

I would counter that. Yes for inductive loads like motors that use the AC directly. But not so much for computer power supplies. The computer supply is rectifying and regulating and filtering the input voltage before it gets to the output. As a result, the P/S input AC waveform doesn’t have a big effect on the DC output. As long as the rectified AC average is above the minimum required by the power converter circuit, waveform and frequency don’t matter much.

Yes, you are converting to DC so it’s less of an issue for the controller. But it is harder on the power supply components (before things go DC).

If it was an old Form 1 with an external supply I’d say the sine wave doesn’t matter. It’s cheap to send a supply from Formlabs or just order one up from a 3rd party.

If you smoke the supply in a Form2 you’ll be sending it back for service. It’s going to end up costing more than the difference between the two backups.

I was wondering about power outages as I consider a form2 purcase, if you have the UPS that Kevin provided a link for, and you are in the middle of a multi hour print , how does the short battery time help you save the print?

The printer is rated for a 65W power draw in operation. A 650WH UPS will power the printer for ~10 hours. 1600WH would run the printer for about a full day. The printer doesn’t draw a lot of power.

For comparison’s sake, my workstation PC is attached to a UPS and it draws about 400W in operation. I have a 2000WH UPS for this system. But that doesn’t give me 5 hours because I also have a bunch of displays and network equipment plugged in to the UPS too. If I lose power, I get about 1.5 hours of hold up time before I have to shut down. Which is usually enough time to fire up the generator to keep the system alive if, for example, I’m in the middle of a big 3D scene render…

Thanks Randy, for explaining that. So the specs on the one Kevin linked to: Capacity: 1500VA / 900W
the 900 is watt hours and that the battery capacity in total watts it can supply. Whats the 1500 number designate?

Well, no. Unfortunately. Confusing as hell. “VA” and Watts can be the same thing. But for some types of electrical loads they aren’t. VA is equal to Watts when the “Power Factor” of the load is 1. A light bulb has a PF of 1. Computer equipment may have a PF that’s lower, this makes the UPS less efficient. It’s up to you to figure out if your load has a PF of 1 or not, which is something that’s not easy to do. So typically you would use the lower of the two numbers when sizing a UPS for a given load. But in both cases, these numbers are the maximum load the UPS can support, not how long it can support the load for.

The actual hold up time of the UPS is a little more work to figure out. Usually, you have to check the manufacturer’s specifications for the particular UPS you’re looking at, and then do some math.

The UPS Kevin linked to is rated for 2 minutes at full load. Assuming they mean 900W, the power-storage capacity of the UPS is 900W * 1/30th-of-an-hour = 30WH. 900W for 2 minutes is the same energy output as 30W for one hour. The printer draws 65W (though I suspect in practice it’s only drawing that peak occasionally and the average is lower) so it would nominally last for 30/65*60=27 minutes with this UPS…

After quick look on amazon it looks like then if you want several hours of battery capacity you talking $600 plus for one of these devices. Are there any other lower cost alternatives that would power the printerto finish a longer print?

It’s primarily a function of battery capacity, and big batteries cost $. You can save money with a UPS that uses Lead Acid batteries vs. Lithium, but in my experience the Lead Acid batteries don’t last long. I don’t like to have to worry about testing my UPS all the time to be sure the battery hasn’t worn out. But the cost scales roughly with “hold up time” because it’s just batteries. Twices as much hold up time requires twice as much battery capacity and since batteries are probably the most expensive part of the UPS, the higher capacity UPS costs about 2x as much.

If you’re an electrically minded individual, you could buy a smaller capacity UPS that uses Lead Acid batteries, and then splice in an external battery of a larger capacity. A typical car battery will deliver about 500WH of energy (but you’d want to be sure to get a sealed or AGM/Gel type). A setup like this wouldn’t look pretty, though there’s no way I can think of to do it on the cheap that would (look pretty).

500WH would give you about 8 hours assuming the printer pulls 65W all the time. More if it’s average is lower. I am nearly certain that it is (lower). The heater is likely the biggest part of the power budget and it doesn’t run all the time. The motors come next and they don’t run all the time either. Laser and Galvo power is probably just a few Watts. Peak power may be 65W but I’m guessin’ average is a lot lower (and average is what you care about)… maybe one of the FL guys will jump in and tell us.

Just an FYI, the UPS I linked above has 118 mins on the display. Due to the excessive heat we had this summer (110 degrees + for a week or more) we had several outages. A few lasted only about 20 mins. In 2 of those cases we were mid print and the prints were safe. We had another power outage on Aug 30th which lasted all day (roughly 12 hours). I didn’t watch the UPS…I went home, but when I returned the next day, the UPS was dead and the print was lost :slight_smile:

Thanks for the info Randy & Kevin.

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