There is a setting on the opener that stops it going up, and going down. It is a manual stop that flips a switch on the motor. A separate (as in not included) light sensor or a timer turns the motor on each time. The motor comes with an electrical adapter that plugs in to a standard 110V outlet. If your coop isn't wired, and you can't (or don't want to) run an extension cord, then you'll need to add a 12V battery and a solar panel. A couple of sources for the D20 Add-A-Motor are:
I bought mine from Smarthome and got good service, and they are running a special at the moment, about $20 less than the other site.
- Add-A-Motor D20
- Timer or photo cell switch
- Vertical sliding pop door
- 110 volt outlet for the D20 power adapter
If you don't have 110V power available, then you'll also need:
- 12 Volt battery (can be a small sealed unit for emergency sign, gate openers, etc.)
- Solar panel (or you could just charge the battery every couple of weeks)
Of note, the D20 motor is a strong little unit. With the internal gearing it will lift quite a bit of weight, so that should not be a concern. I was worried about that and didn't need to. The lift cord that comes with the unit is very thin, but extremely strong. I put the D20 Add-A-Motor on my chicken tractor with a timer/battery/solar panel and have had no worries. It opens and closes a 13x17 inch plywood (T1-11 siding) door each morning and night. Some recommend against wood sliding doors because of binding problems due to moisture changes. I simply made the sliding track wide enough to account for moisture changes in the wood. The D20 comes with a mounting bracket. The motor can be adjusted on the bracket so placement of the bracket is not all that critical. The timer I used is an inexpensive unit used to control deer feeders (Cabelas, Bass Pro Shop, or internet). I have my timer set to come on for about 20 seconds each morning and night. Note, the timer just turns on the motor and does not control the amount of lift of the D20 motor, the manual stops on the motor do that. The timer is set for long enough for the D20 to do it's job, then it shuts the power off.
Here is a cutout from the instructions for the D20, the "stop switch" is just a toggle switch:
You can find a pdf file of the full instruction sheet at: http://www.smarthome.com/manuals/31427.pdf