Not all combinations of computer model, firmware, battery, and operating system tolerate that a battery is replaced while the computer is in operation: If you are using a computer with replaceable battery, you should avoid to swap the battery while the computer is running. Although Battery Monitor is prepared for this situation and handles it correctly, the hardware of the computer might not always register that a battery has been swapped in mid-operation, depending on circumstances. It could happen that information which is usually constant, like battery name, manufacturer, serial number, or date of production, remains stored by the computer, and is not updated erroneously. This can cause readings in the capacity log to be associated with the wrong battery.
Solution: Please consult the operations manual of your computer whether swapping the battery is permitted during normal operation. If yes, we recommend the following procedure: Connect the external power supply, quit Battery Monitor and put the computer to sleep mode. Then replace the battery, wake the computer, and restart Battery Monitor.
With some of the latest battery models and macOS versions, the manufacturer info may unexpectedly disappear: If you run Battery Monitor with certain combinations of hardware model and operating system, the identification of the battery manufacturer may sometimes disappear from the main window after waking your Mac from sleep mode.
Solution: This is a known defect of specific macOS versions. The operating system driver communicating with the battery may lose the battery manufacturer entry during the wake procedure and no longer publishes it to user Apps. Restart the computer to resolve this problem. Apple may or may not fix this problem in future versions of macOS.