PHYS102: Introduction to Electromagnetism

The reading in our textbook explained what a battery is at a basic level. The important thing to keep in mind is that batteries can be charged and discharged, but they do not create new charges. Batteries contain a mechanism (usually chemical) that can maintain a charge imbalance between the positive and negative terminals even if you allow charges to flow between the two terminals through an external circuit like a light bulb. When a battery "loses its charge", that means that the chemical process that was designed to maintain the charge imbalance has stopped working.