10.23
ELECTRICAL
10
Charging System “Break Even” Test
The “break even” point of the charging system is the point at
which the alternator overcomes all system loads (lights, etc.)
and begins to charge the battery. Depending on battery condition
and system load, the break even point may vary slightly. The
battery should be fully charged before performing this test.
1. Connect a tachometer to the engine.
2. Using an inductive amperage metering device, (set to DC
amps) connect to the negative battery cable
3. With engine off and the key, kill switch, and lights in the
ON position, the ammeter should read negative amps
(battery discharge). Reverse meter lead if a positive reading
is indicated.
4. Shift transmission into neutral with the park brake on and
start the engine. With the engine running at idle, observe
meter readings.
5. Increase engine RPM while observing ammeter and
tachometer.
6. Note RPM at which the battery starts to charge (ammeter
indication is positive).
7. With lights and other electrical loads off, the “break even”
point should occur at approximately 1500 RPM or lower.
8. With the engine running, turn the lights on and engage
parking brake lock to keep brake light on.
9. Repeat test, observing ammeter and tachometer. With
lights on, charging should occur at or below 2000 RPM.
Charging System Alternator Tests
Three tests can be performed using a multimeter to determine
the condition of the stator (alternator).
TEST 1: Resistance Value of Each Stator Leg
1. Measure the resistance value of each of the three stator
legs: Y1 to Y2, Y1 to Y3, and Y2 to Y3.
Each test should measure: 0.19 ± 15%
NOTE: If there are any significant variations in
ohm’s readings between the three legs; it is an
indication that one of the three stator legs maybe
weak or failed.
TEST 2: Resistance Value of Each Stator Leg to Ground
1. Measure the resistance value of each of the stator legs to
ground: Y1 to Ground, Y2 to Ground, Y3 to Ground.
Each test should measure: Open Line (OL)
NOTE: Any measurement other than Infinity (open)
will indicate a failed or shorted stator leg.
CAUTION
Do not allow the battery cables to become
disconnected with the engine running. Follow the
steps below as outlined to reduce the chance of
damage to electrical components.
WARNING
Never start the engine with an ammeter
connected in series. Damage to the meter or
meter fuse will result.
Do not run test for extended period of time.
Do not run test with high amperage accessories.
Test
Connect Meter
Leads To:
Ohms Reading
Battery Charge Coil Y1 to Y2 0.19 ± 15%
Battery Charge Coil Y1 to Y3 0.19 ± 15%
Battery Charge Coil Y2 to Y3 0.19 ± 15%
Test
Connect Meter
Leads To:
Ohms Reading
Battery Charge Coil
Y1, Y2, or Y3
to Ground
Open Line
(Infinity)
Y1
Y2
Y3
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