Electronic Cat Flaps

[CDP]

I need to buy a cat flap for DIY installation. As I only want my cat to come in I'm looking for an electronic flap that uses the microchip the vet injects for identification.

I'm not sure how long batteries are likely to last but I prefer the idea to having to connect a mains cable to the door. Or are batteries a really bad idea?

Please could you recommend a flap and retailer.