For your consideration:If it doesn't work one morning that's a risk I'm willing to take.
I don't know anything about the unit you are getting but my PulletShut runs on 12V. There are 2 options including 120V grid power and a solar panel that charges their battery. Not knowing if I had enough sun for that to work and having no power in the barn when I got the door I stole 2 standard 6V lantern batteries from a lantern that uses 4. They lasted 9 months and I replaced them with the other 2 which lasted another 9 months. I think I'm pushing 2 years on most recent 2 alkaline batteries. Your door may use more or less power than mine to operate twice a day. If your door is 12V you could use a standard car battery but it would be a lot heavier, though rechargeable.