Battery Monitor is a small auxiliary application useful in maintaining the life and optimization of a laptop battery. It offers the following features:
Display of the charge state in the Dock: This is useful if you cannot or do not like to use the display in the menubar of OS X, e.g. when you have a screen which is not very wide.
Display of internal battery information: In addition to the charge state, many other technical specifications, e.g. age, temperature, discharge current, number of charge cycles, expected lifetime, or capacity can be retrieved. The states of each of the battery cells and the manufacturer of the cells can also be determined.
Capturing charge and discharge curves: The history of the readings measured by the battery unit can be displayed graphically. This way you can plot the charge and discharge curves, for example, one of the most important characteristics for the health of a battery. You can also review the graphical profile of the amperage drawn by the computer, helping to find "power guzzling applications".
Bookkeeping of the aging process of the battery: Battery Monitor automatically keeps a log about the charge capacity of the battery which will decrease as the battery ages. This helps you to exactly monitor how the behavior of the battery is changing over time. You can assess if your battery is working normally or if it might be defective. You can also estimate more exactly when the right time has come to purchase a new battery. For computers with replaceable battery units, Battery Monitor can of course monitor multiple battery packs at the same time.
Notifications during charge or discharge: In addition to the display of the charge state in the Dock, Battery Monitor can optionally inform you about the progress of the charge or discharge process by other means. Inobtrusive notifications using speech or the Notification Center of OS X can be set up.
What's new in Battery Monitor
Added support for the new battery management of the 10th generation MacBook Air and the 17th generation MacBook Pro. Capacity values and battery unit serial numbers will now be shown correctly for these models.
Added a workaround for situations where the operating system provides contradicting battery health information.
Fixed a problem for Macs with Apple Silicon where the system installation date may have been shown instead of the manufacturing week.
I really like the data supplied by Battery Monitor. Alas—no way to only have it via menubar. I seriously dislike "always running apps" that need to be shown in the dock. Just because of it I don't use it, though I own it. I end up running FruitJuice—less data, but much better UI (and I also like the maintenance features).