iRobot Roomba Discovery, Service Manual

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Appendix J: Battery Test Procedure
Using Battery Voltage Tester
Objective :
To measure voltage across a Roomba battery, to measure voltage across a 5-Ohm resistor, and to measure the thermistor
resistance.
Equipment :
Battery Voltage Tester, Multimeter, and fully charged battery under test.
Method
1.
Fully charge battery with Roomba and latest software.
2.
To measure voltage across the battery, set the multimeter to measure DC VOLTAGE ( V ), and plug the multimeter terminals to the
positive (+) and negative (-) terminals of the charge barge. Failure if reading is not between 15.5 – 18V.
3.
To measure the voltage across a 5 Ω resistor, follow step 1 (set the multimeter to measure DC VOLTAGE), and press the 5-Ohm
resistor push button (Caution
:
Do not press button for more than a few seconds to avoid overheating of the load. Failure if voltage
drop is more than 2 Volts.
4. To measure the thermistor resistance value (thermistor contact to ground contact), set the multimeter to measure RESISTANCE ( Ω ),
and plug the multimeter terminals to the thermistor terminal and the negative (-) terminal. Failure if not within specs in table below.
Ambient
Room
Temp
Thermistor
Min (K
Ohm)
Thermistor
Max (K
Ohm)
10 to 17 C
12.0 21.8
18 to 25 C
8.5 15.5
26 to 33 C
6.0 11.0
34 to 41 C
4.3 7.8