Sony BC M150 - Manual (Page 38)

Precautions
8(EN)
Note on charging an excessively drained battery
pack
If a battery pack is attached to a camcorder and is being used,
the power to the VTR section of the camcorder will be cut off
before the battery pack becomes fully drained. If the camcorder
remains on with the battery pack still attached, the battery pack
will be further drained. The result is an excessively drained
battery pack.
If you try to charge an excessively drained battery pack that
supports the INFO function, the battery charger will not
recognize it as an INFO function battery pack and will begin
charging it as if it were a battery pack without the INFO
function. In this case, charging will proceed without any
problem, but the battery capacity, number of charging cycles,
and other information will not be displayed during charging.
If the battery pack is removed after it has been charged a
certain amount, and then reattached to the battery charger, it
will be recognized as an INFO function battery pack and the
battery capacity, number of charging cycles, and other
information will be displayed as it continues to charge.
No matter in which way the battery pack is charged, after
charging has completed, the battery pack will operate as an
INFO function battery pack.
About memory effect
Nickel metal hydride battery packs suffer memory effect just
like the nickel cadmium battery packs. If this happens,
discharge the battery pack completely or use the refresh
function (pages 3(EN) and 16(EN)).