I was thinking today that I should power the pet component of my device with a rechargeable battery.
One of the biggest complaints of consumers that use the other pet-tracking devices on the market is that the batteries run down quickly. Using a rechargeable battery could help keep the cost down maybe, if not with the life of the battery.
Perhaps for version 2 I can plan for a dynamo - using the activity of the pet to power the battery!
I like the sound of this company: http://www.greenbatteries.com/