User`s guide

Power and Your Computer
2–2
General Battery Information
All batteries have limited life span. A battery’s life span is measured by the number of
charging and draining cycles it can undergo before it can no longer be charged. The
amount of time that your system can be operated by battery power before the battery is
drained is referred to as battery run time.
Nickel Metal Hydride Battery Care
Nickel-Metal Hydride (NiMH) batteries are extremely common in many types of
portable systems, such as cellular phones, camcorders and portable computing devices.
Memory Effect
A NiMH battery in poor condition may begin to exhibit characteristics of memory
effect. Memory effect will occur when a user does not allow the battery to fully drain
before charging it again. For example, if you use the battery for 20 minutes at a time
and then recharge it, the battery will tend to “remember” that it only needs to operate 20
minutes per charge. As a result, during the charging process, the declining battery will
only receive a portion of its charge capacity.
NiMH Battery Life
Memory effect has a direct impact on the battery’s life span. NiMH batteries have a
typical life of up to 800 (charge/drain) cycles. If the battery is used an average of 30
minutes per cycle, you can expect a total life of 400 hours. If you use the battery 3 hours
per cycle, you can expect a total life of 2,400 hours. Therefore, it is advantageous to use
the battery as much as possible during each cycle.
However, in attempts to prevent the memory effect, it may not always be practical to
continuously use your notebook until the battery drains to its minimum level. As a
solution, Digital recommends that you periodically form or condition the battery. When
a battery is formed, it is put through a series of charging and draining cycles. A battery
which is formed will perform better and last longer than a battery which has not been
formed.
If your system will not be in use for more than 30 days, Digital recommends that you
remove the NiMH Battery from the system. When a NiMH battery is removed from the
system, it has a shelf life of approximately 90 days before a charge cycle is required.