REGULATION:
continually because his battery keeps running down, but all battery and
alternator tests pass.
Solutions:
• If alternator reads in the low end of the OK range, it is
working fine. For people driving short distances, however, the
battery may not charge fast enough, causing the battery to run
down slowly. A higher amperage alternator may be necessary to
insure faster charging.
• Some shorting or grounding may occur and slowly drain
battery. Use a low range ammeter and check to see that no
current flows from the battery with engine and all accessories
turned off (including clocks). If current is flowing, locate cause
and repair. Look for such things as trunk, hood, ashtray and
glove compartment lights, bad switches, etc.
• Ammeters installed after vehicle manufacture may not have
sufficient wire gauge to carry current without causing a voltage
drop. This can reduce battery-charging rate, Measure the voltage
drop from battery positive to alternator output terminal. If the
drop is greater than 0.5 volts, and all connections are clean and
tight replace all wire between the two points with wire that is one
gauge heavier.
• Aftermarket accessories may add enough load to the
charging system to exceed alternator capacity (i.e., stereos,
telephones, defoggers, etc.). Replace alternator with one of
higher capacity.
Dual Battery System
• When load testing check each battery separately with cables
disconnected, so a problem with one battery is not masked by
another battery.
• Charging system should be checked with both batteries
connected.
• Accessories may be connected to one or both batteries. Be
alert to their wiring differences in testing for problems.
To charge a battery, the alternator must produce a voltage higher than the
battery voltage to cause current to flow into it. Therefore, the voltage must
rise to the “OK” test zone of the ALT. & REG. TEST band.
Before testing, run the vehicles engine at fast idle with all the accessories
off for at least 5 minutes to recharge the battery and to stabilize the
temperature of the alternator. (Remember, the following tests are valid
only if the battery has passed the Battery Load Test (See page 9). For the
following tests, continue running the engine at fast idle).
The battery is recharged when the voltmeter reading has stabilized at its
highest reading. Observe the voltmeter reading in the “ALT. & REG. TEST”
band:
ALTERNATOR TEST
1.
If in HI zone (See Figure A): Apply
a normal accessory load, such as
lights, heater and wipers.
2.
If the reading drops more than
0.5 volts, there may be a wiring and/
or connector problem between the
alternator output and battery positive
(+).
If the alternator is producing
adequate charge, and the pointer
stays in the OK band, the charging
system is OK, and the test is complete
(see Fig. B).
3.
If the meter is in the low band
replace the alternator (see Fig. C)
OUTPUT:
4.
Apply a Load upon the battery
until the Volts drop to 12.6 to 12.8. At
that moment,
read Amps and add the key draw
amps (10-20 Amps). The Load Amps
+ Key Draw Amps = Total alternator
output.
Troubleshooting
Alternator
(Hypothetical Situation)
Problem: Customer returns
4
FIG. A
FIG. B
FIG. C
12
13
