Lenovo ThinkPad T40 Hardware Maintenance Manual - Page 47

Checking, backup, battery

Page 47 highlights

Checkout guide 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. 4. If the voltage is more than +11.0 V dc, measure the resistance between battery terminals 4 and 5. The resistance must be 4 to 30 K . If the resistance is not correct, replace the battery pack. If the resistance is correct, replace the system board. 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 battery pack (see "1010 Battery pack for 14.1-in. LCD models" on page 71). 4. Remove the backup battery (see "Checking the battery pack" on page 40). 5. Measure the voltage of the backup battery. See the following figure. Red (+) Black (-) Wire Red Black Voltage (V dc) +2.5 to +3.2 Ground v If the voltage is correct, replace the system board. v If the voltage is not correct, replace the backup battery. v If the backup battery discharges quickly after replacement, replace the system board. General descriptions 41

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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.
4.
If
the
voltage
is
more
than
+11.0
V
dc,
measure
the
resistance
between
battery
terminals
4
and
5.
The
resistance
must
be
4
to
30
K
±
.
If
the
resistance
is
not
correct,
replace
the
battery
pack.
If
the
resistance
is
correct,
replace
the
system
board.
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
battery
pack
(see
“1010
Battery
pack
for
14.1-in.
LCD
models”
on
page
71).
4.
Remove
the
backup
battery
(see
“Checking
the
battery
pack”
on
page
40).
5.
Measure
the
voltage
of
the
backup
battery.
See
the
following
figure.
Red (+)
Black (-)
Wire
Voltage
(V
dc)
Red
+2.5
to
+3.2
Black
Ground
v
If
the
voltage
is
correct,
replace
the
system
board.
v
If
the
voltage
is
not
correct,
replace
the
backup
battery.
v
If
the
backup
battery
discharges
quickly
after
replacement,
replace
the
system
board.
Checkout
guide
General
descriptions
41