Electrical System 90 UENR0623-02 Alternator output should be 28 ± 1 V on a 24 V system and 14 ± 0.5 V on a 12 V system. No adjustment can be made in order to change the rate of charge on the alternator regulators. If the rate of charge is not correct, a replacement of the regulator is necessary. For individual alternator output, refer to Specifications, “Alternator”. 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 i04371153 V-Belt - Test NOTICE Ensure that the engine is stopped before any servic- ing or repair is performed. To maximize the engine performance, inspect the poly v-belt for wear and for cracking. Replace the poly v-belt if the belt is worn or damaged. Check the poly v-belt for cracks, splits, glazing, grease, displacement of the cord and evidence of fluid contamination. Voltage drops that are greater than the amounts in table 15 are caused most often by the following conditions: The poly v-belt must be replaced if the following conditions are present. The poly v-belt has a crack in more than one rib.
Loose connections More than one section of the poly v-belt is displaced in one rib of a maximum length of 50.8 mm (2 inch). Corroded connections Faulty switch contacts Diagnosis Procedures To replace the poly v-belt, refer to Operation and Maintenance Manual, “Alternator and Fan Belts - Replace”. 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. i03923009 Electric Starting System - Test 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. 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. Never turn the disconnect switch off while the engine is running. Serious damage to the electrical system can result.
Table 14 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 ter- minal of the starting mo- tor solenoid “+” 8 to 10 V 16 to 20 V Solenoid terminal “Bat” to the solenoid terminal “Mtr” 0.4 V 0.8 V 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