A USB Ammeter is an invaluable tool for diagnosing battery or charge issues on iPhones. Techs use them all the time as you can at least see if the phone is drawing any current when you expect that it should. It doesn’t tell you everything but it should be in every tool kit if you are troubleshooting devices.
CoconutBattery (or 3uTools for Windows) is also great (and should also be in your toolkit) but only viable when you can boot into a phone. If the phone doesn’t boot, CCB or 3uT won’t see the device and won’t give you any information on the charge state.
This is a simple [https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=USB+Ammeter|USB Ammeter], suitable for iPhones and iPads. If you need a USB-C connection (Android, newer MacBooks), then look at the one linked in Jesse’s answer.
A USB Ammeter is an invaluable tool for diagnosing battery or charge issues on iPhones. Techs use them all the time as you can at least see if the phone is drawing any current when you expect that it should. It doesn’t tell you everything but it should be in every tool kit if you are troubleshooting devices.
CoconutBattery (or 3uTools for Windows) is also great (and should also be in your toolkit) but only viable when you can boot into a phone. If the phone doesn’t boot, CCB or 3uT won’t see the device and won’t give you any information on the charge state.
[https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=USB+Ammeter|USB Ammeter]