    AST RESEARCH, INC.         TECHNICAL BULLETIN #0750                  04-01-92

                       PREMIUM EXEC NI-CAD BATTERY INFORMATION

    PROBLEM:       All Nickel-Cadmium (Ni-Cad) rechargeable batteries have the
                   inherent "memory" property that can cause early low voltage
                   indications and premature system shutdown.

    CAUSE:         When a Ni-Cad battery is put through repeated partial-
                   discharge / recharge cycles, and is drained to approximately
                   the same level each time - down to half capacity, for example
                   - it develops a "memory" of this point in the discharge
                   process.  Once established, Ni-Cad memory distorts the
                   battery's voltage output profile.  The battery will produce a
                   normal voltage until drained to the memorized location, but
                   thereafter its voltage output abruptly sags to a sub-normal
                   value, and stays below normal until actual battery depletion.
                   The voltage depression can be deep enough to cause the
                   Notebook to prematurely issue the low battery warning (audible
                   beep and lighted amber LED) or battery fail warning (audible
                   beep and blinking amber LED.)

    SOLUTION:      The Ni-Cad battery "memory" effect can be corrected by
                   "conditioning" the battery, a process which simply consists of
                   fully discharging the battery before recharging.

                   The battery pack should never be disturbed while the system is
                   in use or while the battery is being charged.  To remove or
                   install a battery, the system should be powered down and the
                   AC adapter removed.

                   AST recommends conditioning the battery pack monthly to
                   promote optimum performance.  Conditioning of new, out-of-the-
                   box Ni-Cad battery pack is also strongly recommended. Listed
                   below are the steps required to correctly condition the
                   Premium Exec Ni-Cad battery:

                   1. Charge the Ni-Cad battery up to full capacity.

                   2. Disconnect the AC adapter.

                   3. Configure the Notebook's Setup Menu as shown below.

    IMPORTANT:     Note that Suspend must be ENABLED!

                   Default Speed:       HIGH
                   Backlight Timeout:   0
                   Hard Disk Timeout:   0
                   Suspend:             ENABLE
                   Software Timeout:    0
                   (Exec SX-25 and
                   SX-25 color only)
                   Turbo Mode:          ON AT BOOT
                   Speaker:             ENABLE
                   Other Parameters:    Don't care

    This configuration results in a near-maximum load on the battery during the
    first part of the conditioning process. Suspend mode then prevents an
    excessive drain rate as the battery nears depletion.

                   4. Store  the setup  menu setting  and exit.   The system will
                      reboot and the screen will display the DOS prompt.

                   5. Keep  the Notebook powered up with its LCD display open for
                      12 TO 24 HOURS.

    Most will find that overnight conditioning of the battery is the most
    convenient method.

    It is safe to use the Notebook in the normal fashion during the conditioning
    process.  However, the following precautions must be observed:

                      a. Save your work and exit all applications back to the DOS
                         prompt immediately after the first low battery warning.
                         Allow the Notebook to remain powered up with the LCD
                         display open, however.

                      b. A full 12 hours of on-time will insure complete battery
                         discharge even with premature suspend activation caused
                         by the "memory" effect.

                   6. After 12 hours, turn the Notebook off.  Recharge the
                      battery by attaching the AC adapter.  Connect the AC
                      adapter to the Notebook before plugging the adapter into
                      the AC socket.  Connecting the AC adapter in this sequence
                      insures that the Notebook battery management system senses
                      all signals on the DIN connector appropriately.

    NOTE:  After completing a "fast discharge", wait at least 5 minutes before
    connecting the AC Adapter/Charger to recharge the battery.  If this is not
    done, the AC Adapter/Charger could switch to Trickle Charge mode instead of
    Fast Charge mode.