Machines and Accessories 97-03

Date:  June 13, 1997

Subject:  Cassette Book Machine (CBM) Battery Care

Proper battery care of NLS audio playback machines can
enhance machine performance and increase patron
satisfaction.  Overcharge and deep discharge reduce the
service life of batteries.  The C-1 has no circuitry to
automatically limit either overcharge or deep discharge, but
these conditions can be controlled manually.   For manual
control, leave the idle unit connected to a wall outlet for
about fourteen hours to charge it, then use it for about six
hours while disconnected.  Repeat this cycle to continue
extending battery life.  While this procedure is desirable,
it is both inconvenient and unexpected in a consumer
appliance.  To ease patron concern and inconvenience while
accepting a small decrease in performance, the CBM may be
left continuously connected to a wall outlet.  Under no
circumstances should the C-1 run without a battery
installed.  Running without a battery causes a reduction in
sound quality, a slowing of fast-forward/rewind, and
increased stress on internal components.

The C-2 machine may be connected to a wall outlet
continuously without affecting battery life or machine
performance.  When so connected, the C-2 will operate
correctly with or without a battery installed.  When not
connected to a wall outlet, the C-2 will stop abruptly when
the battery is discharged.  When discharged, the unit must
be connected to a wall outlet for about fourteen hours to
charge the battery sufficiently to achieve at least six
hours of portable operation.

Although new CBMs are shipped from the factory with a fully
charged battery, self-discharge occurs within about thirty
days.  This discharge could happen during transit and
temporary storage at the machine-lending agency (MLA).  NLS
recommends that MLAs charge and test machines to ensure only
CBMs with fully charged batteries are shipped.  Patrons will
then be able to play the instruction tape without assistance
and without having to read any printed or braille enclosure.

MLAs are reminded that the factory-installed battery must
remain with CBMs that are under warranty.

For further information contact:

John Cookson, Head
Engineering Section