TM 9-2320-211-20
this occurs, replace the battery. Check the batteries
2-22. Batteries
for damaged case, terminals, or cell cover plates.
CAUTION
C e r t a i n precautions must be observed
voltmeter. select the 50-volt scale and check the
before beginning any tests on the 24-volt
voltage charge status. Individual battery voltage
system. Do not permit a hot wire to touch
must not be less than 11 volts or more than 13
metal parts of the vehicle at any time. Flash
volts.
testing by striking a hot wire against a
ground will cause an arc that will com-
pletely destroy the connector on the lead.
This is caused by 24 volts in the system.
Personnel who have been accustomed to
using this type of test on 6- or 12-volt
systems must be very careful not to forget
that they are working with higher voltage.
a. Battery Indicator. Vehicle batteries should be
tested prior to performing any electrical checks in
the vehicle. This vehicle has two 12-volt batteries
connected in series furnishing 24 volts to the
electrical system in accordance with figure 2-10.
This vehicle has a 24-volt electrical system that uses
a negative (--) ground and a positive (+) power
feed to the electrical components. Turn on the
ignition switch and observe the battery indicator in
accordance with figure 2-10.
c. Individual Battery Check Using Load Bank
(1) Connect one end of the positive ammeter
lead to the 12 volts, 50-50-100A load bank ter-
minal of the tester (fig. 2-8), and the other end to
the positive (+) terminal of one of the batteries.
(2) Connect one end of the negative ammeter
lead to the 100 AMP ammeter terminal of the
tester (fig. 2-8), and the other end to the negative
( -- ) terminal of the same battery to which the
positive lead is connected.
(3) Connect one end of the voltmeter positive
lead to the voltmeter positive terminal of the tester
(+) terminal of the battery to which the positive
ammeter lead is connected.
b. Battery Test.
(1) Specific gravity. Use a battery hydrometer
and check each battery cell. Water should not be
a d d e d prior to this test. Battery specific gravity
r e a d i n g s should be at least 1.225 in each cell.
Variation of more than .025 gravity points per cell
(temperature corrected) indicates a battery fault. If
