How to restore corroded or fuzzy batteries back to life for a limited amount of time
3WARNING - I will NOT be held responsible for any damages the methods shown and described in this video may cause to yourself or someone else, including (but not limited to) material, moral, and/or corporeal damages. Any information you choose to put into use from this video is done AT YOUR OWN RISK. Battery acid can be very corrosive and can cause immediate harm to yourself and others around you, as well as damage to items and surfaces that come into contact with battery acid. Ensure to sand down corrosion deposits lightly using a sheet of sandpaper BY HAND, and to afterwards use up the remaining power in the battery promptly (for example in a high-drain device). NEVER leave a battery that is developing corrosion in an electronic device when said device is not in use, as the emitting battery acid can cause irreparable damage to your electronic device. If you or someone else comes into contact with battery acid, wash hands and the affected area immediately and dispose of the leaking batteries promptly.
This video will show you how batteries that have developed corrosion on the contacts (often a dark black or green deposit or a white, fuzzy deposit) can be lightly sanded using sandpaper on the contacts to expose the contact surface, which can permit these batteries to be used again, albeit for a shorter amount of time than non-corroded batteries, as the battery will continue to slowly leak, discharge, and re-develop corrosion.