Garage door opener and UPS

[east_tn_emc]

I have a Liftmaster door opener on the workshop that works great. Is there any reason that I cannot use a properly sized computer/IT UPS to power the opener? I know Liftmaster makes several openers with battery backups in the event of a power failure, I just do not see a need to replace the opener and I have several UPS units sitting around.

Just curious to know if anyone else has used, say, an APC UPS with their opener.

 

[rharman]

Check the load requirements on the opener vs. what your UPS can supply.

No experience but, if you've got the UPS on-hand, give it a try.

 

[BFBOB]

Yep, I've done similar things. The power output of the UPS matters, but so does the energy capacity. You need to make sure that your opener draws no more power (watts or VA; either is close enough) than the UPS can put out. Then, figure how many open/close cycles you need and calculate the energy required. Let's say your opener draws 1000 watts and you want it to open and close 10 times. Each operation takes around 20 seconds; call it 30 for easy calculation, and that's 10 minutes of usage, or 1/6 hour. 1/6 hour times 1000 watts is 167 Watt-hours. Look at the battery in the UPS. It will usually be a 12V battery with a rating of 4-12 Ampere hours. Pick the middle, multiply 12V by 8Ah = 96 Wh. That's not enough, but you can get another 12V 8Ah battery and wire it in parallel with the one in the UPS. That will give you the energy capacity you need.
Don't forget you never get the full energy capacity out of a battery except at a very low rate of discharge, so use a bigger one than you think you need.
Of course, you'll need to plug in your own numbers, but that's the calculation. I've had to do this many times to keep telephone modumbs running for significant periods. Sometimes it's taken a battery of nearly car size to do the trick.

(def: modumb: noun, an electronic device used by people who are dumb enough to allow their landline phone service to disappear when the power disappears)

 

[nehog]

As a computer geek, and a mechanic, I can say yes it will work, but the UPS needs to be able to handle the current. Check the spec plate on the opener, and the UPS and make sure the UPS can deliver more power than the opener requires.

 

[2ManyProjects]

I have a Liftmaster door opener on the workshop that works great. Is there any reason that I cannot use a properly sized computer/IT UPS to power the opener?

The short answer is "No; it can indeed work."

HOWEVER... The key phrase in your question was "properly sized"; and that is probably nowhere near as simple as it might initially seem. In addition, and at least as importantly, it needs to be the right TYPE of UPS.

I know Liftmaster makes several openers with battery backups in the event of a power failure, I just do not see a need to replace the opener and I have several UPS units sitting around.

WHICH particular UPSes? Specific makes and models. Yes, it's important.

Most "inexpensive" so-called "UPS" devices sold for use with desktop computers aren't really "UPS"es, in the sense of providing truly uninterruptable power. To do that requires what the marketeers have since dubbed a "True On-Line UPS" (which tend to be MUCH more expensive than the low-end "standby" systems). This issue, in and of itself, is probably not a major concern for a Garage Door Opener; worse-case, the GDO gets "confused" if the power happens to go out in mid-cycle, and it "sees" the resulting short gap in supply power at exactly the wrong moment.

Of MUCH greater concern is the waveform produced by the "UPS" when running on battery power. Again, the "inexpensive" models generally produce what is euphemistically referred to in the ads as "Modified Sine Wave" -- really a glorified stepped-square wave -- because that is much cheaper to implement than TRUE sine-wave output. And motors in particular do NOT get along well with this sort of pseudo-sine wave power.

Just curious to know if anyone else has used, say, an APC UPS with their opener.

Of the various APC products, I would not attempt this with anything but one of the larger models from the "Smart-UPS" line (well, OK... a Symmetra system would probably also work; but that's just silly). The "Smart-UPS" series is still not a true "on-line" UPS; but it at least does produce sine-wave output. The same cannot be said for the "Back-UPS" and "Back-UPS Pro" lines.

As for WHICH specific model you'd need, that gets a bit tricky. You first need to inspect the data plate on the opener itself, to determine its MAXIMUM current draw. Then you need to generously size the UPS relative to that, in order to accommodate the additional load imposed during the start-up surge (which can be several times the "running" draw -- and note that UPS systems are not nearly as tolerant of such short-term overloads as a normal AC powerline is!). Note that when checking your UPS specs, the (typically lower) "Watts" figure is far more relevant than the (typically higher) "Volt-Amps" figure, due to this being a motor load. In short, "Bigger Is Better"; so when in doubt, go still bigger. And since larger-capacity UPS models also tend to have larger batteries, this will also address "BFBOB"'s concern regarding the number of open/close cycles you can expect to get out of one charge.

 

[ybnormal70]

How about you plug the garage door opener into the UPS system and try it. Work it a few times and see if/how it works. Worst case it trips the UPS and it doesn't work. No harm in trying. I've tried this method testing UPS system batteries with large lights and as soon as it gets to much for the UPS it just turns off. It doesn't hurt anything.

I'd also guess that these garage door openers that have them built in aren't a high dollar UPS system since they don't cost much more than a regular door opener.

Just my thoughts about it.

Kevin

 

[2ManyProjects]

How about you plug the garage door opener into the UPS system and try it. Work it a few times and see if/how it works. Worst case it trips the UPS and it doesn't work.

That's not exactly the worst possible case. While unlikely, it is possible to damage either the UPS or the door opener, if an especially "unfortunate" combination were arbitrarily thrown together.

No harm in trying. I've tried this method testing UPS system batteries with large lights and as soon as it gets to much for the UPS it just turns off. It doesn't hurt anything.

Lights and motors are two different things -- two VERY different things, in this context.

I'd also guess that these garage door openers that have them built in aren't a high dollar UPS system since they don't cost much more than a regular door opener.

Door openers which have (or offer as an option) battery backups are designed from the get-go for that, and use DC motors. That side-steps the whole "sine wave vs. square wave" issue, and eliminates about 90% of the circuitry required in a "normal" UPS.

 

[eljefino]

How do you plan on wiring this? Most door openers plug into the ceiling. Will you be hanging heavy batteries overhead? Running lots of helter skelter extension cords across the ceiling and down the wall?

The old fogey in me says don't do this. If the power goes out, pull the red string and open the door manually. You should have a keyed entrance anyway. UPSes might be smarter now but my older one will give its last gasp of ripply nasty voltage as its battery wears out-- not the thing you want unattended. I use it as designed, running my computer with me present, and shutting down the comptuter and saving my work when the lights go out.

If you have some handicapped person who absolutely needs the garage door to work, come up with a less hokey system.