When you start Mac Power Monitor, it is by default in the operating mode continuous monitoring. Here, a power measurement by macOS is performed once per second. The results are displayed live in all statistics windows of the program that you have currently opened. This process repeats itself without interruption in the next second.
If desired, you can stop the continuous measurement at any time and resume it later. A central button Start/Stop in the Monitoring Control window is used for this purpose. The control window appears together with the overview window automatically after startup, unless you leave additional windows of the program open via the Resume function of macOS.
The control window can be closed at any time. To reopen it, select the menu item Window > Show Monitor Control or press the key combination ⌘ + 0.
You can also control continuous monitoring via menu by clicking Commands > Stop Monitoring, or Commands > Start Monitoring, respectively. Alternatively, you can also use the key combination ⌘ + R.
In addition to the control window, Mac Power Monitor uses other windows to display the various measurement results. You can work with any selection of eight other result windows. All window types can be opened via the Window menu. The corresponding types will be described in more detail in the following chapters. You can open all result windows suitable for your Mac model simultaneously by selecting the menu item Window > Open All Supported Monitor Windows or by pressing the key combination ⌘ + ⇧ + A.
The measurement operation is carried out by a macOS process that runs simultaneously alongside user applications, i.e. it also affects power metrics and consumes energy as well as other resources of the computer. The goal of Mac Power Monitor must be to keep the effort for measurement as low as possible so that the operation itself does not have a significant impact on the data for the rest of the system. The error caused by running the measurement program should be as small as possible.
Each time you open or close a result window of the program, Mac Power Monitor analyzes which measurement data is required for the windows currently displayed. If necessary, the measurement process is briefly interrupted in order to send a modified command to macOS to reduce the amount of observed readings to the smallest possible level, or increase it if necessary.
For this reason, the Stop button in the control window can briefly change its status, and in all result windows, data updates may be temporarily interrupted when you open or close other result windows. A newly opened window receives the current readings after a waiting period of one second.
Errors may occur when macOS is performing the measurement. This can happen, for example, if the clock setting is changed in the system, when the computer enters sleep mode during a long-term measurement, or if the current load is so high that user programs and measurement process displace each other.
Mac Power Monitor performs an automatic plausibility check of all readings and tries to avoid that errors can affect the resulting data. Dubious or impossible results are automatically corrected to a reasonable maximum value.
Mac Power Monitor uses bar graphs in many places to vividly display measured values. In advance, it won’t be clear for all graphics which scale should be chosen, i.e. which concrete measured value should be symbolized with a full scale deflection (100%). For this reason, the program uses a self-learning method after each launch that adjusts the scales for the affected bar graphs. This can have the effect that certain charts are temporarily inaccurate immediately after startup and show excessively high values. However, this settles very quickly, so that you get a correct and suitable scale for each bar graphic after a short time.
The value for the CPU’s maximum power consumption is not learned upon each start, but is kept permanently over several sessions of the program. For Macs with Apple Silicon, this also applies to the overall performance of GPU cores and to the distribution of bandwidths of the individual core types, as indicated in the overview window.
Bar graphs in which high values are considered critical (in terms of energy and resource consumption) usually use a green color representation for values below 80% of the maximum, and yellow for values above. Since an overload can never occur, a red color representation is only used in exceptional cases.
In addition to continuous measurement every second, you can also perform a one-shot measurement for a duration of your choice. The minimum duration of the measurement is one millisecond, i.e. 0.001 s. During a one-shot operation, the continuous measurement is automatically stopped when it is running and all result windows are temporarily removed from screen.
Perform the following steps to perform a one-shot measurement:
A wait dialog appears. During measurement, most controls of Mac Power Monitor are basically blocked. Once the time has elapsed, all result windows that you had previously selected for measurement will be opened automatically.
Extreme values (e.g. a data field for a maximum reading) or average values are omitted in the result windows to avoid misleading information. Since only a single measurement took place, each measured value would be an extreme value at the same time. For the same reason, most bar charts or history graphs are also shown without values in this situation.
Mac Power Monitor is under continuous development and new versions will be published in irregular time intervals. These updates are usually free unless a completely redesigned product will be released. The latest version is always available for download via the official web site. Mac Power Monitor can check if a new free update is available for the version you are currently using. To do this, select the menu item Mac Power Monitor > Check for Updates. The program will connect to the Internet and inform you about the results. In case a newer version is indeed available, you can choose to open your web browser to be automatically guided to the download page.
Instead of performing a manual check by clicking the menu item, you can alternatively enable Mac Power Monitor > Automatic Update Check to let the application search automatically for updates in regular intervals.