So today I changed my batteries for the first time in a year on my healthy pet simply feed model pfd00-14574. I first got this because I was getting annoyed by tiger always meowing for food. I feed her twice a day and figured this was the best option to separate me from the food. It worked great and worked well when I travel. I have a cat genie so litter box isn't a problem. I never read instructions... opening battery box i noticed a power port. It is for an optional $20 power pack to plug into the wall. After some research online I found it is a pretty common ac adapter. I found an old chatter box ac charger that met the specs and it worked. Guess it pays not to throw everything away.