Komatsu 830E-AC Shop Manual page 196

Battery Control Box
Battery control box (4, Figure 2-1) is located to the
left of the battery box. This box contains the battery
disconnect switches and other components listed
below.
Battery Disconnect Switches
Battery disconnect switches (7 & 8) provide a conve-
nient method of disconnecting the truck batteries
from the truck electrical circuits without having to
remove any battery cables. Rearward disconnect
switch (7) opens the cranking motor battery circuit
only, preventing engine startup while still allowing
battery power to the 24VDC control system circuits, if
desired. Forward disconnect switch (8) disconnects
the 24VDC system circuit.
24VDC Auxiliary Battery Receptacles
Two pairs of receptacles (2), located near the battery
disconnect switches, are provided to attach battery
charger leads for charging the batteries.
These receptacles can also be used for connecting
external batteries to aid engine starting during cold
weather. When external batteries are used, they
should be of the same type (8D) as the batteries
installed on the truck. Two pairs of batteries should
be used. Each pair should be connected in series to
provide 24VDC, with one pair connected to the front
receptacle and the other pair connected to the rear
receptacle on the truck.
Isolator Diode
A Schottky type isolation diode (9) is used to provide
isolation between the electrical system battery cir-
cuits and the dual cranking motor start command cir-
cuits. This device controls the direction of current
flow in high current applications.
Engine Start Relay
Engine start relay (6) receives the signal to begin
cranking from the start relay located on relay board
RB6. When the engine start relay is activated, it pro-
vides current to the cranking motor motors to engage
the drives and begin cranking the engine, eliminating
the need for magnetic switches.
D2-6
24VDC to 12VDC Converter
24VDC to 12VDC converter (1, Figure 2-2) is used to
convert the 24 volt battery system voltage to 12 volts
for various truck components such as the radio/cas-
sette player, cab power windows, and the auxiliary
power receptacles in the cab.
The converter is powered by the cranking motor cir-
cuit batteries. Converter output circuits are protected
by CB60, a 50 amp circuit breaker (5, Figure 2-1)
located inside the battery control box.
Observe and verify polarity, connection points,
and correct circuit numbers if relay replacement
is necessary. Incorrect hookup will damage the
solid state relay.
FIGURE 2-2. AUXILIARY CONTROL CABINET
24 VDC Electric Supply System
(LEFT WALL)
1. 24VDC to 12 VDC Converter
D02034