16
Battery Testing – 12 Volt
BATTERIES
DISCHARGE TEST
If the previous tests have failed to identify the problem, conduct a discharge test. The discharge test comes closest
to simulating actual vehicle operating conditions by continuously drawing current from the batteries until voltage
drops to 42.0 volts.
The discharge test is the hardest test on the batteries and the most time-consuming to perform. Use the battery
discharge tester (CCI P/N 101831901).
Performing the Discharge Test
1.
Be sure the batteries are fully charged and that the electrolyte level is correct in all cells.
2.
Connect the tester leads to the positive (+) post of battery no.1 and negative (–) post of battery no. 4
(Figure
16-3, Page 16-6)
.
3.
Check and record the electrolyte temperature of the battery packs. Check cell no. 2 (second cell from positive
post) in each battery.
4.
Reset discharge machine and turn the tester ON.
5.
When the batteries have been discharging for approximately 60 minutes, set the discharge machine to function 3
and check battery set voltage. Check voltage every 10 minutes throughout the rest of the test. As soon as the
battery set voltage reaches 0.5 volts above the shut-off point (42.0 volts), use a multimeter to measure individual
battery voltages. Measure and record the voltage of each battery to the nearest 0.01 volt.
See following NOTE.
NOTE:
The tester will shut off automatically when shut-off voltage is reached.
POS
NEG
POS
NEG
2
4
1
3
POS
POS
NEG
NEG
(–)
1
(+)
2
TESTE
R
(Viewed from driver side of vehicle)
1. RED probe to battery no. 1 (+).
2. BLACK probe to battery no. 4 (-).
719
Figure 16-3
Battery Discharge Test – 4 x 12 Volt Battery
Configuration
Page 16-6
2009 Electric Precedent Maintenance and Service Manual
