The condition of charge in the battery at each regular inspection will show if the charging system is operating correctly. An adjustment is necessary when the battery is constantly in a low condition of charge or a large amount of water is needed. There are no adjustments on maintenance free batteries. A large amount of water would be more than one ounce of water per cell per week or per every 100 service hours.
When it is possible, make a test of the charging unit and voltage regulator on the engine, and use wiring and components that are a permanent part of the system. Off-engine testing or bench testing will give a test of the charging unit and voltage regulator operation. This testing will give an indication of needed repair. After repairs are made, perform a test in order to prove that the units have been repaired to the original condition of operation.
The charging rate of the alternator should be checked when an alternator is charging the battery too much or not charging the battery enough.
Alternator output should be 28 ± 1 volt on a 24 volt system and 14 ± 0.5 volt on a 12 volt 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 Specification, “Alternator and Regulator”.
See Special Instruction, REHS0354, “Charging System Troubleshooting” for the correct procedures to use to test the charging system. This publication also contains the specifications to use when you test the charging system.