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 ELECTRICAL SYSTEM
TESTING AND ADJUSTING
condition of the charge in the battery. Damage to the
charging unit will result if the connections (either positive
or negative) between the battery and charging unit are
broken while the charging unit is in operation. This is
because the battery load is lost and there is an increase
in charging voltage. High voltage will damage, not only
the charging unit, but also the regulator and other
electrical components.
Load test a battery that does not hold a charge
when in use. To do this, put a resistance across the
main connections (terminals) of the battery. For a 6, 8 or
12V battery, use a test load of three times the
ampere/hour rating (the maximum test load on any
battery is 500 amperes). Let the test load remove the
charge (discharge) of the battery for 15 seconds and with
6V7070 HEAVY-DUTY DIGITAL MULTIMETER
the test load still applied, test the battery voltage. A 6V
battery in good condition will show 4.5V; and 8V battery
The 6V7070 Heavy-Duty Digital Multimeter is a
will show 6V; a 12V battery will show 9V. Each cell of a
completely portable, hand held instrument with a digital
battery in good condition must show 1.6V on either a 6, 8
display. This multimeter is built with extra protection
or 12V battery.
against damage in field applications, and is equipped
with seven functions and 29 ranges. The 6V7070
CHARGING SYSTEM
Multimeter has an instant ohms indicator that permits
continuity checks for fast circuit inspection. It also can
The condition of charge in the battery at each
be used for troubleshooting small value capacitors.
regular inspection will show if the charging system
operates correctly. An adjustment is necessary when the
The 6V7800 Regular-Duty Digital Multimeter (a
battery is constantly in a low condition of charge or a
low cost option to the Heavy-Duty Multimeter) is also
large amount of water is needed (more than one ounce
available; however, the 6V7800 Multimeter does not
of water per cell per week or per every 50 service hours).
have the O1A range or the instant ohms feature of the
6V7070 Multimeter.
When it is possible, make a test of the charging
unit and voltage regulator on the engine, and use wiring
NOTE: Make reference to Special Instruction Form No.
and components that are a permanent part of the
SEHS7734 for more complete information for use of the
system. Off-engine (bench) testing will give a test of the
6V7070 and 6V7800 Multimeters.
charging unit and voltage regulator operation. This
testing will give an indication of needed repair. After
BATTERY
repairs are made, again make a test to give proof that
the units are repaired to their original condition of
operation.
Before the start of on-engine testing, the
Never disconnect any charging unit circuit or battery
charging system and battery must be checked as shown
circuit cable from battery when the charging unit is
in the Steps that follow:
operated. A spark can cause an explosion from the
flammable vapor mixture of hydrogen and oxygen
1.
Battery must be at least 75% (1.240 Sp. Gr.)
that is released from the electrolyte through the
fully charged and held tightly in place. The
battery outlets. Injury to personnel can be the result.
Battery holder must not put too much stress on
the battery.
The battery circuit is an electrical load on the
charging unit. The load is variable because of the
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