garage door opener

What size batteries it use to open in case of power failure? 2 6.5 amp or 2 13 amp?

Ya makes sense sounds like a small nickle cadmium pack that uses 20 double AA batteries. I figured it would use 6.5 amp or 13 amp lead acid battery. The answer really is that you would have to replace the battery pack with something larger as I think even a 5 watt panel would overcharge those. IF it uses .12 ah every day for opening once then you would need a very very small panel.

You would need 2 of these in series. http://www.surplusshed.com/pages/item/r3208p.html

But you would have to add a blocking diode.
Might consider doing a larger project. Get 2 large deep cycle 12 volt batteries, wire them into the door opener, buy a 60 watt panel or 2 and an inverter and solar charger. Then throw your tv or something else on it. If the solar bug hits ya, you can go from there. Trying to solar power those nicad packs won't be very fun or helpful. My guess is 2 years after they were installed they would have a hard time opening and closing the door once without going flat. Have you unpluged it and ran the door up and down till it stops working?

Hi Kon Pik
Sounds to me like you want start small and learn from first hand experience. I can respect that. There is quite a bit of stuff to learn believe it or not and, it is possible that things could go horribly wrong and you have a fire or, at the very least you will have bought ether not enough or too much equipment or "gear" as you put it.

This is what we know.
1 - 24 volt - 1.2 amp hour capacity battery
I can only assume 4 amps is the door openers, motor name plate rating and the 7.5 amps for 3 seconds is the start up surge. It can run through 10 open/close operations per (12 hr.?) day on battery power alone.
How long does an open/close cycle last? Not including the time it takes to drive the vehicle in or out. 2 minutes to open, 2 minutes to close? 1 minute each?

If this one battery can do all of that then all it needs is a very,very small maintenance PV battery charger. I agree with Mr. Winter's recommendation of the 2 - 1 watt PV modules in series. Even then you may not want to put them in full sunlight all day long. Maybe just catch a few hours in the morning. You'll have to experiment with that and hope the battery doesn't overcharge, swell up, and bust. To be honest with you, I don't even know if anyone makes a charge controller that "small".

Does the door openers manufacture have any recommendations?