I have M1 MacBook Pro (16 inch) fully charged, and connected to the charger and a LG 27' monitor, which has own power adaptor. Strangely, M1 MacBook Pro drains its battery level down from 100% to 80% and holding its level. Why does it drain the battery level? This will require additional charging and appears that it is not good for the laptop.
MacBook Pro (2020 and later)
https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries
From the above: "A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell."
https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries
From the above: "A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell."
In fact, it is good for your laptop's battery which is why MacOS does that.
"Based on the measurements that it collects, battery health management may temporarily reduce your battery's maximum charge. This happens as needed to ensure that your battery charges to a level that's optimized for your usage—reducing wear on the battery, and slowing its chemical aging."
Thank you for your helpful reply! I am curious what is the chemistry behind this seemingly contradictory behavior.
M1 MacBook Pro battery charge level with external monitor
