This document is printed from SPI². Not for RESALE
i03923009
Electric Starting System - Test
General Information
Power which is available during cranking varies
according to the temperature and condition of the
batteries. Table 14 shows the voltages which are
expected from a battery at the various temperature
ranges.
Table 14
Typical Voltage Of Electrical System During Cranking At Vari-
ous Ambient Temperatures
Temperature 12 V System 24 V System
−23 to −7°C
(−10 to 20°F)
6 to 8 V 12 to 16 V
−7 to 10°C (20 to 50°F) 7 to 9 V 14 to 18 V
10 to 27°C (50 to 80°F) 8 to 10 V 16 to 24 V
Table 15 shows the maximum acceptable loss of
voltage in the battery circuit. The battery circuit
supplies high current to the starting motor. The values
in the table are for engines which have service of
2000 hours or more. The voltage drop for new
machines is less than the voltage shown in table 15 .
Table 15
Maximum Acceptable Voltage Drop In The Starting Motor Cir-
cuit During Cranking
Circuit 12 V System 24 V System
Battery post “-” to the
starting motor terminal “-”
0.7 V 1.4 V
Drop across the discon-
nect switch
0.5 V 1.0 V
Battery post “+” to the
terminal of the starting
motor solenoid “+”
8 to 10 V 16 to 20 V
Solenoid terminal “Bat”
to the solenoid terminal
“Mtr”
0.4 V 0.8 V
Voltage drops that are greater than the amounts in
table 15 are caused most often by the following
conditions:
• Loose connections
• Corroded connections
• Faulty switch contacts
Diagnosis Procedures
The procedures for diagnosing the starting motor are
intended to help the technician determine if a starting
motor needs to be replaced or repaired. The
procedures are not intended to cover all possible
problems and conditions. The procedures serve only
as a guide.
NOTICE
If equipped with electric start, do not crank the engine
for more than 30 seconds. Allow the starter to cool for
two minutes before cranking again.
Never turn the disconnect switch off while the engine
is running. Serious damage to the electrical system
can result.
UENR0623 85
Electrical System
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