HP compaq Hardware Manual page 44

Battery Packs
The primary battery pack charges when it is inserted into the
notebook and the notebook is connected to external power.
External power can be supplied through an AC Adapter, the
optional Port Replicator, or an optional Automobile Power
Adapter/Charger.
The battery pack in the travel battery charges when it is attached
to the notebook and the notebook is connected to external power.
External power can be supplied through an AC Adapter or an
optional Automobile Power Adapter/Charger. Because the travel
battery covers the docking connector, the travel battery cannot be
used or charged with a Port Replicator.
Battery packs can also be charged in the optional Universal
Charger. The optional Aircraft Power Adapter can be used to run
the notebook, but cannot be used to charge a battery pack.
While the battery pack is charging, the battery light on the
notebook is on. The light turns off when the battery pack is fully
charged.
Battery light
Hardware Guide 3–11