Here's how to check if your iPhone needs a new battery
question] Recently got my hands on an iPhone 4 running iOS 7.1.2. Should I jailbreak it? Btw it's a 32gb white, I also need to replace the battery. : r/LegacyJailbreak
iOS 16: How to Display iPhone Battery Percentage in Status Bar - MacRumors
At What Health Percentage Should I Replace My iPhone Battery? - AppleToolBox