coconutBattery shows live battery health information for your Mac and for iPhones and iPads connected to it. It has been reading Mac batteries since 2005.

Key features:

Check the battery health of your Mac, iPhone, and iPad.
Save battery health readings to compare later.
See battery details in the menu bar.
Connect to an iPhone or iPad over Wi-Fi instead of USB with Plus.
Review temperature, voltage, charge rate, and operating time with the Plus Battery Lifetime Analyzer.
Get notified when a battery drops below a level you set, and view SSD read and write stats, with Plus.

coconutBattery 4.4 requires macOS 12 Monterey or later and is only available from coconut-flavour.com. The free version covers the basics, and coconutBattery Plus is a one-time purchase of $12.95 for version 4 or $17.95 for a lifetime license, with a trial of 10 launches.