Instructions for replacing batteries are found in your Fishman electronics instructions that are located inside your glove box in your case. On Travel, Parlor, ZAD20 and ZAD50 models the battery compartment is on the bottom 'bout near the bottom strap peg. Simply squeeze and slide out the battery tray. On our 80 and 900 Series guitars the battery is located in the head unit where the controls are. Simply squeeze the tab on the electronics head unit and pull. The unit will fold out and you will see the battery. All Fishman electronics use 9-volt batteries. We recommend rechargeable batteries as higher-level electronics consume a lot of power and can burn through batteries fast. This video will show you in greater detail how to change out the battery on all of our Fishman systems: https://youtu.be/iUY4abz-IHY