Komatsu 830E-AC Shop Manual page 261

PROBLEM
8. When the alternator voltage is measured at the alterna-
tor (B+) terminal, it is considerably higher than alterna-
tor voltage measured at the battery (B+) terminal. What
could be wrong?
D10003 07/06
When there is a difference in voltage measured
between two places in the same circuit, the most
likely cause is excessive resistance in that circuit.
This difference, as measured between two points, is
called a voltage drop. The excessive resistance in the
circuit can be a result of poor connections at the ter-
minals or undersize gauge of the connecting cable.
All connecting cables in any electrical system must
be of sufficient gauge for the length of the cable to be
able to carry the necessary current within the circuit.
If the gauge is too small, the resulting voltage drop
will impair electrical system performance. This is a
critical issue for the charging system because exces-
sive voltage drops in the system, on the positive or
the negative side, can prevent the batteries from
recharging
between the measurements must not exceed 0.8-
Volts for the 28-Volts system. To maintain accuracy
when testing the charging system, measure the volt-
age drop with the alternator at no load and at maxi-
mum load to check how the load current can affect
the voltage. Undersized cables also heat up when
conducting electrical current. This causes the insula-
tion to either soften or get brittle, and represents a
safety hazard in the system.
Battery Charging Alternator
CAUSE/SOLUTION
properly. The maximum difference
D10-31