With coconutBattery you are always aware of your current battery health. It shows you live information about the battery in your Mac and iOS devices (iPhone, iPad)
You can't do it officially, but Coconut battery has been around for a while and I think it's quite trustworthy. I think it uses the sensors and diagnostic data of the device itself to give you information - meaning, it's what Apple sees when they use diagnotstic tools. I could be wrong.
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