IBM ThinkPad X21 2660, Hardware Maintenance Manual

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total power remains; under this condition the battery pack
can charge to 100% of its capacity. This protects the
battery pack from being overcharged or from having a
shortened life.
Note: If the battery pack becomes hot, it may not be able
to charge. Remove it from the computer and leave
it at room temperature for a while. After it cools
down, reinstall and recharge it.
To check the battery pack, do the following:
1. Power off the computer.
2. Remove the battery pack and measure the voltage
between battery terminals 1 (+) and 4 (-). See the fol-
lowing figure:
1(+)
4(-)
2
3
3. If the voltage is less than +11.0 V dc, the battery pack
has been discharged.
4. If the voltage is more than +11.0 V dc, measure the
resistance between battery terminals 3 and 4. The
resistance between battery terminals 3 and 4 must be
from 4 to 30k ohms.
Note: Recharging will take at least 3 hours, even if
the indicator does not turn on.
If the voltage is still less than +11.0 V dc after
recharging, replace the battery.
Checking the backup battery: Do the following:
1. Power off the computer, and unplug the AC adapter
from it.
2. Turn the computer upside down.
3. Remove the backup battery (see “1030 Backup
battery” on page 50).
4. Measure the voltage of the backup battery. See the
following figure.
Terminal Voltage (V dc)
1 + 0 to + 12.6 (6-cell) +0 to 16.8(4-cell)
4 Ground (-)
General descriptions
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