Automatic Charging Systems (Score 1)

A bit Offtopic but this has been driving me insane. I have built a six legged walking robot. Works great. The thing that is driving me bonkers is trying to find information on how to build an automatic charging/docking station. Now I dont mena programming it to find it, or how to wlka towards it, thats no problem. I mean the actual physical device. Where the contacts go, stuff like that. I've already programmed the robot to return to a 'charger' when it's batteries are low, and it works fairly well, but I don't know how to build the charger, or have it cut off the systems while charging, or reactivate them when full.
Thanks