My iPhone is fully charged, and then rapidly looses the charge. This doesn't happen all the time but I really don't want to buy a new iPhone or pay for a new battery yet. What's up.
Yep. It happens. This usually happens after an update to IOS. Especially with IOS 11. Before you buy a new phone or battery, drain the battery fully, Charge the battery. Try this a couple of times.
If the battery works better, do this at least once a month. And after an IOS update.
Another issue may be caused by charging your phone by plugging into a USB port that doesn't meet the charging requirements defined by Apple. Try charging the iPhone with the official charging cable and AC adapter. If things work better you know it maybe that USB port. https://www.zdnet.com/article/iphones-battery-draining-fast-heres-how-to-fix-it/ and https://discussions.apple.com/thread/8180334