IBM ThinkPad R50e Series

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
40 R50e (MT1834, 1842)