Battery health has been in the news a bit the last few years, starting when people found out that Apple intentionally throttles (slows down) older phones in order to help with their battery performance. As a battery gets older, it can’t perform as well, and Apple chose to throttle old phones to help combat that. While Apple handled it poorly, the idea was solid and ultimately helps users. But why do batteries get worse over time, and what can be done to stop it?