Description / Abstract:
1. Scope--This SAE Recommended Practice is intended to apply to lamps,
batteries, heaters, radios, and similar equipment for operation with
mobile or automotive diesel engines. Twenty-four V systems have long
been used for heavy-duty services because 24 V permit operating 12 V
systems in series-parallel. Thirty-two V systems have been used for
marine, railroad-car lighting, and other uses.
Generators, storage batteries, starting motors, lighting, and auxiliary
electrical equipment shall be for nominal system ratings of 12, 24, or
32 V as determined by the power requirements of the application. It is
recommended that no intermediate voltages be considered.
The combination of a 24 V starting motor and two 12 V batteries
connected in series for cranking is considered practical where it can
be adapted to the installation. The batteries are reconnected in
parallel for charging from a 12 V generator/alternator and for
operating lights and other auxiliary equipment, or charged separately
and used individually for lights and other electrical equipment.