TM-9-2350-311-10
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; OPERATOR’S MANUAL
NOVEMBER 1994
TM-9-2350-311-10 - Page 68 of 775
TM 9-2350-311-10
1–14 EQUIPMENT OPERATION AND DESCRIPTION — CONTINUED
1–14.6 Electrical System (Hull)
The electrical system consists of:
a.
b.
c.
d.
e.
f.
g.
BATTERIES. There are four 12V batteries (1) connected in series and parallel to deliver 24 vdc (nominal) to the
master relay (2).
MASTER RELAY. The master relay (2) delivers power directly to the slip ring contact board, engine starter (3),
slave start receptacle (4), and circuit breaker board (5).
MASTER SWITCH. The MASTER switch (6), when activated, draws 24 vdc (nominal) from the batteries (1)
through the master relay (2) to operate the electrical systems. With the MASTER switch in ON position, systems
can be operated without running the engine.
GENERATOR. The generator (7) is engine-driven and delivers 24 vac (nominal) to the rectifier (8).
RECTIFIER. The rectifier (8) is a full-wave, bridge rectifier which converts the generator ac voltage to dc voltage
and delivers it to the voltage regulator (9).
VOLTAGE REGULATOR. The voltage regulator (9) controls the delivery of 24 vdc (nominal) to the vehicle
operating systems through the master relay (2) and also acts as a recharger for the batteries (1) when the engine is
operating.
EXTERNAL POWER RECEPTACLE. The external power receptacle (10) provides vehicle auxiliary power from an
external source.
1-30
Back to Top
