Battery Packs; Running The Notebook On Battery Power - HP Compaq Series Hardware Manual

Running the Notebook on Battery
Power
When the notebook is connected to external AC power, the
notebook runs on AC power.
When a charged battery pack is in the notebook and the notebook
is not connected to external power, the notebook runs on battery
power.
The notebook switches between AC power and battery power
according to the availability of an external AC power source. For
example, if the notebook contains a charged battery pack and is
running on external AC power supplied through the AC adapter,
the notebook will switch to battery power if the AC adapter is
disconnected from the notebook.
You can leave a battery pack in the notebook or in storage,
depending on how you work. Keeping a battery pack in the
notebook enables the battery pack to charge whenever the
notebook is connected to external AC power and also protects
your work in case of a power outage.
On the other hand, battery packs in the notebook slowly discharge
when the notebook is turned off. For this reason, the primary
battery pack is not shipped inside the notebook and must be
inserted before the notebook can run on battery power.
Hardware Guide

Battery Packs

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