預估的電池可用時長與實際情況有出入
您可能會發現，系統所預估的電池可用時長會小於實際可用時長。這是由於「可用時長」只能大略估算，實際情況會依電腦負載、螢幕亮度、網路連線等因素而有所出入。一般而言，預估的可用時長都是比較樂觀的。
In order to estimate the remaining battery life, a number of factors must be taken into account. One is the amount of power currently being used by the computer: power consumption varies depending on how many programs you have open, which devices are plugged in, and whether you are running any intensive tasks (like watching high-definition video or converting music files, for example). This changes from moment to moment, and is difficult to predict.
Another factor is how the battery discharges. Some batteries lose charge faster the emptier they get. Without precise knowledge of how the battery discharges, only a rough estimate of remaining battery life can be made.
As the battery discharges, the power manager will figure out its discharge properties and will learn how to make better estimates of battery life. They will never be completely accurate, though.
If you get a completely ridiculous battery life estimate (say, hundreds of days), the power manager is probably missing some of the data it needs to make a sensible estimate.
If you unplug the power and run the laptop on battery for a while, then plug it in and let it recharge again, the power manager should be able to get the data it needs.