So I thought I bought the super fancy garage door opener when I bought the house.
We lost power both yesterday and today. Turns out No battery back up in the opener.

Manual gives the following power specs:
https://www.liftmaster.com/cat...55w_prodguide_lr.pdf
120VAC
60 Hz Voltage
6A Current Rating

So can I use this $40 backup??
https://www.amazon.com/dp/B01H..._encoding=UTF8&psc=1

Liftmaster wants $95 for their back up device.

I am not sure if what you posted will work. I am surprised Liftmaster is charging that much after the fact, but I believe it. I have a Liftmaster with built in battery back-up and it is nice; I have been able to open and close my garage door at least ten times during a power outage over two days. That is the most I have tested it.

That UPS will work out fine.

My guess is not. That garage door opener motor is going to have a fairly significant start-up current demand, for which that little UPS wasn't designed.

FWIW
There is a release that allows the door to be raised and lowered manually. Granted, it's a PITA but if power outages are not common in your area it may be the simplest solution.

quote:

Originally posted by SPWAMike0317:
FWIW
There is a release that allows the door to be raised and lowered manually. Granted, it's a PITA but if power outages are not common in your area it may be the simplest solution.

Yes but when my wife is the only one home trying to wrangle three kids run to the back then through the house all while a severe storm is knocking down trees.
I’d rather spend a few bucks so she can just pull in the garage.

quote:

Originally posted by ensigmatic:
My guess is not. That garage door opener motor is going to have a fairly significant start-up current demand, for which that little UPS wasn't designed.

The openers with the battery use just a 12v.
https://www.liftmaster.com/for...-openers/model-485lm

Can’t find full specs of the battery.

quote:

Originally posted by Black92LX:
The openers with the battery use just a 12v.
https://www.liftmaster.com/for...-openers/model-485lm

Can’t find full specs of the battery.

That is not meaningful. So does the UPS to which you linked.

Very rough figuring that opener needs maybe 800 Watts (maybe 1000 if you stuff 2X100 Watt lightbulbs into it).

That UPS can only put out 225 Watts so it would probably be very unhappy.

$95 sounds reasonable to me. My wife bought a new reclining couch and found out upon delivery that it was a power recline only. Cost well over $100 for the power supply for each side! They were battery power with 110 v chargers. And I am sure they take a lot less power than a garage door opener. Spend the $95.

Here's the PDF of the manual for the liftmaster system: https://www.liftmaster.com/cat...manuals/114a2745.pdf

It has 2 12v batteries (specs not provided) a fuse, and the logic to control recharging, etc. The 12V batteries -41B591 - can be bought separately at around $15/20 each. Home Depot - $16.67 ea.

Takeaways:
1) I do not think you would be able to gerry-rig cheap generic PC UPSes to get this done.
2) If the batteries alone are close to $20 apiece - meaning the batteries alone are about $40 of the $95 cost of the system - the odds of something ridiculously cheaper doing the job are low
3) If it's not worth $95 to you, teach the wife how to close the garage door manually while the kids are still in the car.

In more reading the LiftMaster unit won’t work with my unit as it has a proprietary plug that my model does not have.
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

quote:

Originally posted by Black92LX:
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

It's more than just the operating current. It's also the start-up current, which can be substantially greater.

What size motor is on your opener? (E.e.: 1/3 HP, 1/2 HP, 1 HP, etc.) I imagine somebody here can probably guesstimate the start-up and operating current.

But I suspect that, in any event, a way more substantial UPS than what you were looking at will be required.

quote:

Originally posted by ensigmatic:

quote:

Originally posted by Black92LX:
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

It's more than just the operating current. It's also the start-up current, which can be substantially greater.

What size motor is on your opener? (E.e.: 1/3 HP, 1/2 HP, 1 HP, etc.) I imagine somebody here can probably guesstimate the start-up and operating current.

But I suspect that, in any event, a way more substantial UPS than what you were looking at will be required.

1/2hp.

I am not opposed to spending more money to get it to work.
Just trying to spend what is needed not more.

quote:

Originally posted by Black92LX:
In more reading the LiftMaster unit won’t work with my unit as it has a proprietary plug that my model does not have.
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

There is probably more in the way than just the plug. If it were that simple I’m sure you (or an electrician) could wire it in.

To work, the system needs to take line voltage, charge the UPS and keep it charged without overcharging it, and to either always run the opener from the UPS or to run it from line when line is available and run it from the UPS when it is not. A little bit of logic (not much, but a little) is required to do that. IFF they put all the logic in their UPS and plugging it in interrupts the current path between the opener and the line running everything through the UPS, then you should be able to rewire and make it work. If any or the logic is in the openers that are compatible and you opener doesn’t have that logic, you are probably out of luck with that opener.

I’ll go take a look at mine (a liftmaster with backup on a 22’x8’ Martin metal door) and see if I can tell anything about how they did things.

ETA: Sorry it took so long to get back to the house and take a gander. There is a two connector plug on the battery backup unit that plugs into the operator. The line voltage cables goes into the operator, not to the backup unit first, then on to the operator. This makes me suspect that a good part of the logic is in the operator. Something to keep from backfeeding the line with the battery, possibly the charge controller, etc. I'd guess you are out of luck on this one, short of putting in a regular UPS that is adequately sized, and that is probably more than you want to bite off.

This message has been edited. Last edited by: slosig,

quote:

Originally posted by Black92LX:

quote:

Originally posted by ensigmatic:

quote:

Originally posted by Black92LX:
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

It's more than just the operating current. It's also the start-up current, which can be substantially greater.

What size motor is on your opener? (E.e.: 1/3 HP, 1/2 HP, 1 HP, etc.) I imagine somebody here can probably guesstimate the start-up and operating current.

But I suspect that, in any event, a way more substantial UPS than what you were looking at will be required.

1/2hp.

Depending upon a variety of factors, it looks like the typical full-load running current of a single-phase, 1/2 HP motor at 125VAC is around 5A. Startup current is (this is a SWAG) probably another 20%, so call it 6A.

However: Those numbers could be as high as 10A and 12A, respectively, and such motors starting/stopping throw tremendous spikes on the line, which many UPS' may not deal with real well.

quote:

Originally posted by Black92LX:
I am not opposed to spending more money to get it to work.
Just trying to spend what is needed not more.

Yeah, well, the problem here is figuring out what will actually work without self-destructing after a few operations.

The standard off-the-shelf UPS was not designed for those kinds of loads.

The spec sheet for your opener is 6a @ 120v. That means that you can be drawing up to 720w. That will overpower the UPS you listed, you would need a 1000w UPS to make sure that it doesn't trip when you use it in normal use.

The cheapest way to fix this is to use the battery designed for the unit.

I have my generator wired for whole house, and we can definitely tell the surge when the opener is used (we use the manual lift release, but wanted to see if it could be done).

That UPS is probably too small to run a 1/2 HP motor. Additionally, the batteries in that UPS unit cannot be replaced, so it only has a service life of 3-4 years, if it even worked for your application.

quote:

Originally posted by Black92LX:

quote:

Originally posted by ensigmatic:

quote:

Originally posted by Black92LX:
I have reached out to LiftMaster to see how many watts the motor operates at and if they have a suggestion.

It's more than just the operating current. It's also the start-up current, which can be substantially greater.

What size motor is on your opener? (E.e.: 1/3 HP, 1/2 HP, 1 HP, etc.) I imagine somebody here can probably guesstimate the start-up and operating current.

But I suspect that, in any event, a way more substantial UPS than what you were looking at will be required.

1/2hp.

I am not opposed to spending more money to get it to work.
Just trying to spend what is needed not more.

1/2 HP = approx 375w, start up about 3 times that.

UPS are not made for starting motors. Didn't look at your link, but I'm pretty certain your not considering a UPS that can handle in excess of 1,000w.

Timely topic. Both of our backup batteries went bad within a day of each other. These are for a Chamberlain unit.

I got Duracell replacements for $32 each at Batteries Plus. Ordered online and picked up at store, saved 10%. Replacements fit and work perfectly.