You can contact Buybuystore directly in NYC via the phone. They sell replacement batteries for 300-350$ depending on the voltage. When the battery is no good you order a new one. When the unit arives its the entire unit. You get the new controler, battery ect.... A controlers life is about that of your average battery so its a good deal when you look at the cost. One great pluss to the system Kysmo uses is the battery unit is sealed.