PMU Power Management

zbz0529

PMU Power Management [Copy link]

Apple has always been low-key in dealing with the PMU issue, and the design architecture of PMU is not uniform, so that most Apple fans fail to pay attention to the importance of PMU. Tomahawk feels it is necessary to explain the use and understanding of PMU again.

PMU, the full name of which is Power Management Unit. It is responsible for the power supply management, LCD screen backlight, hard disk hibernation, system sleep and activation reset, digital touchpad management, communication port identification, and most importantly, charging regulation in the Apple system. The functions are complicated and indispensable.

Apple notebooks are equipped with composite lithium-ion batteries. According to the physical characteristics of lithium batteries, its advantage is that it eliminates the "memory characteristics" and does not require charging every time the battery capacity is used up. As long as there is a need to charge, it can be charged to full capacity at will. Before the new (virgin voyage) lithium battery is used, no matter how much the battery capacity is at the factory, it must be charged for 8-12 hours before it can be officially discharged. Continuous normal use of charging and discharging three times, generally starts to be in good condition on the fourth time. Lithium batteries are also very sensitive to temperature. Try to keep it at 15-25 degrees Celsius for the best charging and discharging state.

As for the charging mode of lithium batteries, it is different from other rechargeable batteries. There is a fixed time constant for charging lithium batteries. Generally, it takes 4-4.5 hours to charge for every 1000 mAh lithium battery. If you charge too slowly, it will not work, and if you charge too quickly, the battery pack will explode. Therefore, the concept of PMU power management was derived. In the last 90%-95% of the charging of lithium batteries, PMU implements an extremely slow charging mode of fine drip leakage to enhance the total capacity of the charged battery. If you charge too quickly, the battery pack cannot be fully charged. Therefore, fans should not believe in the so-called "fast charging", "medium charging" and "slow charging" theories of various chargers outside. The key is that PMU is the real son of destiny. Tomahawk recommends that you must use the original charging adapter. (The above application theory can be extended to the lithium battery of mobile phones)

After talking for a long time, let's get back to the topic. Steve Jobs also didn't tell Tomahawk the real reason, which is that Apple's PMU settings will crash uncontrollably in certain situations, leading to some abnormal situations, such as the battery not charging, not fully charging, false charging, abnormally inaccurate battery display, and many more that cannot be listed in full. In short, it's a disease.

Well, if it's a disease, treat it. Tomahawk is powerless and can only "rely" on itself to solve the problem by itself, because Chinese Apple people are pitiful, and it's amazing to rely on themselves! First...

reset the system default settings data reset:
1. Restart,
2. Immediately press and hold the Apple key + Option key + O + F,
3. Enter the firmware kernel, type reset-nvram, and press Enter.
4. Then type the command reset-all and press Enter.
5. Automatically restart to the desktop.
6. Calculate the battery health level again. Is it normal?
7. The battery is obedient, no need to read on. Please browse other wonderful posts!
8. If the battery still won't obey, please continue reading...

As Apple computers have changed generations, the PMU reset has also evolved. Different models use different PMU settings. Some models use a direct "hard" reset switch, while others use a "soft" reset switch.

G4/867, G4/1000, 15" titanium hot pot machine, use a "hard" reset switch, and the PMU reset is as follows:
1. Turn off the computer. Remember to turn it off!
2. Carefully flip up the black keyboard block.
3. Under the F12 key, find a small metal button.
4. Press the PMU reset metal button for 5 seconds. 5 seconds is enough. Don't be greedy. It's 5 seconds.
5. Cover the keyboard block.
6. Turn on the computer, reset the time and date, and check other presets.
7. Please continue to browse other wonderful posts!
8. Newbie, small plane, big plane, what to do? Please read on........

Newbie, 12" small aircraft, 17" large aircraft, using the "soft" reset switch, PMU reset as follows:
1. Turn off the machine. Remember to turn it off!
2. Press Shift+Control+Option+Power switch. (Be careful not to touch the fn key)
3. Press and hold for 5 seconds, 5 seconds is enough, don't be greedy, 5 seconds.
4. Turn on the machine, reset the time and date, and check other presets.