After launching the application, the Overview Window of Battery Monitor will appear. It shows all important operational data of your battery and information about your computer. If you have closed the window, you can reopen it again by selecting the menu item Window > Overview or by pressing the key combination ⌘ + 1.
The window contains the following items:
Modern battery units from Apple typically use the Impedance Track™ Battery Gas Gauge Chipset from Texas Instruments as battery processors. These controllers identify with a chip code beginning with “bq20z…”.
For Apple devices manufactured after August 2021, Apple may no longer permit that the actual manufacturing date can be determined. In this case, Battery Monitor will indicate this with a respective message.
If you are using a recent version of macOS with a recent Mac, Battery Monitor will display a help button with a question mark next to the battery status bar. If you click this help button, you can display a graphical overview that further clarifies the differences between the percentage given by macOS and the actual charge level of the battery cells.
Battery reserve shows the value at which macOS puts the computer into hibernation as a precaution to avoid deep discharge of the battery. In reality, the cells still have enough energy at this point to keep the computer in standby mode for a longer period of time, as well as to operate the screen, showing the “Battery empty” graphic. If you are using an up-to-date version of macOS and you have enabled the item Battery > Battery Health > (i) > Optimized battery charging in the System Settings application, the specific value at which macOS stops charging under certain conditions to save the battery is shown at Possible charging end point. You can also see the differences between an “almost full” and an “actually full” battery.
The battery controller keeps an internal error log that stores abnormal operation events recorded in the past. Such event entries are called “permanent battery failures”. Battery Monitor and macOS can decode 14 different types of failures stored in the battery unit. They constitute the defect list shown when you press the More Info button at Battery defects.
Each recorded failure type appears as a line in the battery defect table. Because the battery unit does not contain its own clock, the records have no associated time information and their order may not reflect the actual sequence in which the events occurred. The different types of defect descriptions should be self-explanatory.
Note that an entry recorded in this list does not necessarily mean that the battery is still defective at the moment. It just indicates that a failure situation has occurred during the lifetime of the unit in the past. Usually, only the vendor of the battery unit can reset the battery’s failure log, using special software which is not available to the public. If a battery unit has been repaired or refurbished, connecting new battery cells with a used battery controller, but the service technician has forgotten to clear the permanent failure memory, the defect list could be outdated and therefore be incorrect.
This value only represents the official replacement policy of Apple and is only valid for original Apple parts, not for battery units of other vendors. It does not take into account the actual health of the battery.
For specific Macintosh models and operating system versions, System Settings (System Preferences in old versions of macOS) also shows a value for the current maximum capacity of the battery. In certain cases, this value can deviate from the value displayed by Battery Monitor. Battery Monitor always shows the up-to-date value, which was determined by the battery monitoring processor based on the observation of the last charge cycle. Apple’s value, on the other hand, is calculated as a nominal long-term capacity, which includes extended observations of the battery behavior and additional correction factors, such as the operating temperature. Macs with Apple chips are particularly affected by this, as they no longer use the classic battery monitoring of macOS, but a control system taken over from the iPhone.
Battery Monitor can detect if you are using a Mac that may be operating under two different definitions of “maximum capacity”. In this case, a help button with a question mark icon is displayed next to the bar graph. If you click this button, the two capacities will be compared.
Current computers use battery cells based on lithium ion technology. Under load, the voltage of a cell will be between 3.3 and 3.8 volts, depending on cell type. The maximum charge voltage of a fully charged cell is approximately 4.2V. Under optimal circumstances, the behavior of all cells of a battery (including their voltages) should be equal, because they have been constructed identically. A worn-out or defective battery can often be detected by a voltage of one cell differing significantly from the voltages of the other cells, because this cell is no longer capable of performing according to its specifications.
The number of battery cells reflected to the outside may not always match the true physical number of cells. For example, a long-life unit with 6 cells might pretend it is actually composed of 3 cells only. For technical reasons, Apple battery units can only report a number between 1 and 4 available cells to the outside.
Newer Macintosh models contain battery controllers that also record long-term data about the battery cells, storing the information permanently, completely independent of the computer. The internal flash memory of the controller is used for this. If Battery Monitor detects such a feature in your Mac, the data can be retrieved via the button Long-term data that appears at the bottom of the box Battery Health.
The amount of accessible data can differ significantly depending on the Mac model. You may only get the full dataset with MacBooks using Apple Silicon and macOS 12 or higher.
If available, you can read the extreme values for voltage, current and operating temperature recorded during the lifetime of the battery. The discharge current is traditionally given as a negative value. Under Battery disconnected you will find an indication of whether the battery unit has been cut off from the associated Mac one or more times in the past. The Memory write operations value indicates how often long-term data was written to the flash memory of the battery. The various capacity values form a part of the dataset on which macOS bases its own battery health percentage (see above). The hour meter of the battery can also be read out, as well as the information when the last charge cycle from “completely empty to completely full” occurred.
As an additional feature, Battery Monitor can also give you an overview of batteries that have been detected in Bluetooth devices currently connected to your Mac. Such devices, for example wireless trackpads or keyboards, are powered by internal batteries. To see the list, select the menu item Window > Bluetooth Battery Overview or press the key combination ⌘ + 0.
Next to the name and serial number of each device, you’ll see the current battery capacity, both as a bar indicator and numerical percentage value. An additional color marker indicates whether the battery state is considered normal (green) or in a warning situation (red), running on reserve. If the marker is missing, the respective device does not support a continuous battery alert status. Battery Monitor tries to detect as many batteries in classic Bluetooth or Bluetooth Low Energy devices as possible, but we cannot guarantee that all connected devices are listed here. Some vendors use encryption to intentionally protect their battery data against access by third-party software.
A Bluetooth device must be connected to your Mac to appear in the overview window. You cannot monitor devices which are just in the neighborhood.
For technical reasons, Battery Monitor cannot detect whether a Bluetooth device is powered by a rechargeable battery or a single-use battery (primary cell). The external device alone is responsible for monitoring and taking care of the battery, so it usually doesn’t provide any additional details of its power unit the Mac should “know” about. So the overview can just serve as additional convenience. Bluetooth batteries won’t become part of the history data or any notifications managed by Battery Monitor.
While Battery Monitor is running, the current charge state of the battery can also be seen within the Dock tile of the application. The state is represented by a combination of level indicator in a battery symbol, an arrow, color and icons. The display is similar to the menu-bar icon for the battery state shown by macOS and should be self-explanatory. An additional numerical percentage value can be added if desired.
As mentioned before, the shown status can either reflect the true physical or the fake user-oriented charge percentage, depending on what display option you have chosen.
In addition to the graphical display, you can open the context menu of the Dock tile to see the charge level and the estimated remaining time as numerical values. Just right-click the icon of Battery Monitor in the Dock.
Several aspects of the application can be customized to your personal needs. The settings can be reviewed after selecting the menu item Battery Monitor > Settings … or by pressing the key combination ⌘ + ,:
Preference settings are divided into two categories. You can use the tabs General and Notifications to switch between them.
Most applications at the user level, for example Apple’s battery icon in the menu bar, prefer the percentage value for user presentation to indicate the charge level. Because different applications access the battery at different points in time and also use different rounding policies, there can sometimes be a difference of ±1 percentage point. The indicator in the MagSafe connectors of older Apple AC adapters also use the user-oriented “100%” level to switch from orange to green if used with up-to-date Macs and macOS versions. Most applications at the technical level, e.g. the macOS command-line tools for power management or the System Information application reflect the true percentage value, however.
If you are operating the App without a Dock icon, macOS will remove all typical user interface elements usually available to re-activate the App after you have worked with a different program. To switch to Battery Monitor, you will then use the menu items at its icon on the right hand side of the menu-bar instead. The setting Overview window: Open automatically when switching to application will also take effect in this case.
Older versions of OS X and macOS supported a feature to show the estimated remaining runtime of the battery directly in the menu, accessible via the battery icon in the menu bar. Apple removed this feature from this location with macOS 10.12.2 and later versions of the operating system. If you are using one of the affected OS versions, Battery Monitor can be used as a replacement to restore this lost function. This is explained in a separate chapter.
You can avoid the necessary confirmation by pulling the power cord while the warning is shown.
Calibration: A similar warning can be shown when the battery unit detects that the estimated error of the maximum capacity value becomes too large. Battery capacity cannot be measured directly, it can only be estimated by observing the behavior of the battery during a full discharge/charge cycle. The estimate becomes too inaccurate when a full cycle could not be observed for some time. In this case, the recorded data is outdated and may no longer reflect the true state of battery health. The readings for capacity and remaining run time become less and less accurate. Battery Monitor can warn you when the estimated error exceeds a certain threshold. To do this, set a check mark at Warn when estimated error becomes too large. If you receive such a warning, you should re-calibrate the battery at your earliest convenience.
macOS will already give you an automatic warning when the battery is running on reserve power. So the option When running on reserve of Battery Monitor should only be activated if you have suppressed the original warning of macOS for some reason.
Independent of the single “reserve” warning, you can also activate more nagging, repeating warnings, if the charge levels drops below a certain level. The level can be adjusted between 5% and 20%. The reminder message please connect the AC adapter will be repeated every 5 minutes. To use this feature set a check mark for the option As nagging reminders when below and set the threshold value with the slider below it.
The maximum limit for this feature is usually 20% which can mean 4 remaining hours of operation for an up-to-date Mac with healthy battery. For old Macs with a defective battery, you may like to set an even higher limit, however. Hold down the option key ⌥ and click on the numeric value next to the slider to unlock a wider range of possible settings. When you do this, you can set the warning threshold up to 66%.
Battery Monitor can deliver the aforementioned kinds of notifications either via Notification Center or acoustically by voice (or both). You can control this by the check marks at Notification Center and Speech. Note that no notifications will occur if you disable both options. The types of notifications will be explained in more detail in the next section.
Immediately after your computer has woken up from sleep mode, Battery Monitor won’t send notifications for some seconds. Operating system and monitor hardware need a certain time to recover from sleep mode which can temporarily result in wrong status information. Battery Monitor waits until the system has stabilized.
You can setup the details as desired by using the pane Notifications in the application System Settings of macOS (System Preferences in old versions). After Battery Monitor has sent at least one notification message, macOS will offer you the detail settings for the application.
Battery Monitor automatically removes outdated notifications, so you won’t be flooded by charge records from the past which no longer make sense. The Notification Center automatically suppresses notifications while you are working with Battery Monitor in the foreground.
Battery Monitor can also deliver notifications by spoken language. You can control the type of voice and the speed as follows:
It is recommended to use the menu item Customize… of the System Voice pop-up button to select one of the voices for your primary language and to activate high-quality speech mode. High-quality output requires an additional download which is available for free from Apple. Battery Monitor automatically tries to find the “best” voice from your list of available voices which matches the language in which the application is currently running.