The battery only holds the time and date. if it is drained, it will reset the time/date to early 1900 if power is lost to the controller, programming is NOT lost, it is stored in non-volatile memory
The customer must determine if the battery is the watch style batttery or the square yellow Lithium battery.
The watch style is a CR2032 and can be purchased a local drug store/department store for a minimal cost.
The square yellow Lithium battery is located on the top left of PCB, replacements must be shipped from the Conyers office free of charge, they were soldered onto the board during production. We have a retrofit we can send. If a request comes in, have the customer email us their Fedex shipping information and we will send one. Fedex info = Name, Company name, address, zip and phone number.