7.1 Battery-Charging Generator
DETROIT DIESEL 53
Fig. 4 - 20. DN Type 250 A.C. Self-Rectifying Generator(Alternator)
connected correctly (negative to negative and positive
Accidentally reversing the battery connections must be
Never use a fast charger with the battery connected or
Never disconnect the battery while an alternator is in
as a booster for battery output.
operation. Disconnecting the battery may result in
damage to the generator diodes due to the momentary
high voltage and current generated by the rapid collapse
of the magnetic field surrounding the field windings.
The alternator diodes are also sensitive to heat and care
In marine applications which have two sets of batteries,
must be exercised to prevent damage to them from
switching from one set of batteries to the other while the
engine is running will momentarily disconnect the
If faulty operation of an alternator occurs on an engine
unless the field circuit is opened first.
equipped with an insulated starting motor. check to be
sure that a ground strap is present and is correctly
If a booster battery is to he used. the batteries must be
1971 General Motors Corp.