I'm on my third door. I'm now trying Coop Tender
https://cooptender.com It has a battery back-up that powers the motor and maintains timer/dusk-til-dawn feature in case of power outage. It closes with a worm drive shaft that prevents predators from being able to open the door. It has wifi features. The only negative I have so far is stupid chickens can get their heads caught under the door as it is closing. Because it is a strong door, they cannot pull their heads back in if trapped. I've lost two this way in two weeks.
My first door was an Automatic Chicken Coop door
http://www.automaticchickencoopdoor.com It worked great for years. It was mounted as a window in the wall of my chicken house. The hens learned to jump/fly in and it was high enough off the ground where predators could not reach it if their back feet were on the ground. It was a simple drapery motor that pulled a light weight door up and then let it descend. It had no locking mechanism other than gravity, but I never experienced any predator breach with exception of when we had a power outage. This door had no battery back-up drive and could not be closed without power. We suffered severe losses when there was an extended power outage when we were out of town.
My second door was a Pullet-Shut
https://www.chickendoors.com It has two raccoon design flaws. Number one, the door is designed to open outward. Because my chicken house is located in my cattle pens, the door had to be recessed so the open doors folded back against the walls of the entrance tunnel. Had we mounted the door directly on the exterior of the house, window-style, the swinging doors of the Pullet-Shut would have been vulnerable to damage from a passing cow rubbing on them. The recessed area created a handy shelf for raccoons to comfortably sit while working their fingers into the door closure. They were able to pull it open enough to gain access to the interior of the chicken house. The second design flaw is other than the motor mechanism, there are no exterior stops that prevent the doors from being pulled out. The perfect design for this door would have been for the doors to open inward and on the interior side of the doors there be bolts that recede to open and ascend when closed, similar to a safe or bank vault. We suffered great losses with this door due to repeated predator breach.
