2007 MITSUBISHI LANCER EVOLUTION battery

ENGINE ELECTRICAL -Charging System16-2
CHARGING SYSTEM
GENERAL INFORMATION
The charging system uses the alternator output
to keep the battery charged at a constant level
under various electrical loads.
OPERATION
Rotation of the excited field coil generates AC voltage in
the stator.
This alternating current is rectified through diodes to DC
voltage having a waveform shown in the illustration at left.
The average output voltage fluctuates slightly with the
alternator load condition.
When the ignition switch is turned on, current flows
in the field coil and initial excitation of the field
coil occurs.
When the stator coil begins to generate power after
the engine is started, the field coil is excited by
the output current of the stator coil.
The alternator output voltage rises as the field
current increases and it falls as the field current
decreases. When the battery voltage (alternator
S terminal voltage) reaches a regulated voltageof approximately 14.4 V, the field current is cut
off. When the battery voltage drops below the
regulated voltage, the voltage regulator regulates
the output voltage to a constant level by controlling
the field current.
In addition, when the field current is constant, the
alternator output voltage rises as the engine speed
increases.
SYSTEM DIAGRAM
Stator coil
Field coil
Voltage
regulatorEngine-ECU
Charging
warning lampIgnition
switchBattery B
G
L
FRS
Voltage
Time
Approximately
14.4 V

ENGINE ELECTRICAL -Charging System16-3
ALTERNATOR SPECIFICATIONS
ItemsSpecifications
TypeBattery voltage sensing
Rated output V/A12/90
Voltage regulatorElectronic built-in type
SERVICE SPECIFICATIONS
ItemsStandard valueLimit
Alternator output line voltage drop (at 30 A) V-max. 0.3
Regulated voltage ambient
tempatvoltageregulatorV
-20_C14.2 - 15.4-
temp. atvoltage regulatorV
20_C13.9 - 14.9-
60_C13.4 - 14.6-
80_C13.1 - 14.5-
Output current-70 % of normal output current
Rotor coil resistanceΩApprox. 3 - 5-
Protrusion length of brush mm-2
SPECIAL TOOL
ToolNumberNameUse
MB991519Alternator test
harnessChecking the alternator (S terminal voltage)

ENGINE ELECTRICAL -Charging System16-4
ON-VEHICLE SERVICE
ALTERNATOR OUTPUT LINE VOLTAGE DROP TEST
Alternator
Terminal BVoltmeterAmmeter
Battery
+-
+-
This test determines whether the wiring from the
alternator “B” terminal to the battery (+) terminal
(including the fusible line) is in a good condition
or not.
(1) Always be sure to check the following before
the test.
DAlternator installation
DAlternator drive belt tension
(Refer to GROUP 11 - On-vehicle Service.)
DFusible link
DAbnormal noise from the alternator while
the engine is running
(2) Turn the ignition switch to the “LOCK” (OFF)
position.
(3) Disconnect the negative battery cable.
(4) Disconnect the alternator output wire from the
alternator “B” terminal and connect a DC test
ammeter with a range of 0 - 100 A in seriesbetween the “B” terminal and the disconnected
output wire. (Connect the (+) lead of the
ammeter to the “B” terminal, and then connect
the ( - ) lead of the ammeter to the disconnected
output wire.)
NOTE
An inductive-type ammeter which enables
measurements to be taken without
disconnecting the alternator output wire should
be recommended. Using this equipment will
lessen the possibility of a voltage drop caused
by a loose “B” terminal connection.
(5) Connect a digital-type voltmeter between the
alternator “B” terminal and the battery (+)
terminal. (Connect the (+) lead of the voltmeter
to the “B” terminal and the connect the ( - ) lead
of the voltmeter to the battery (+) cable.)

ENGINE ELECTRICAL -Charging System16-5
(6) Reconnect the negative battery cable.
(7) Connect a tachometer or the MUT-II.
(Refer to GROUP 11 - On-vehicle Service.)
(8) Leave the hood open.
(9) Start the engine.
(10)With the engine running at 2,500 r/min, turn
the headlamps and other lamps on and off
to adjust the alternator load so that the value
displayed on the ammeter is slightly above 30
A.
Adjust the engine speed by gradually
decreasing it until the value displayed on the
ammeter is 30 A. Take a reading of the value
displayed on the voltmeter at this time.
Limit: max. 0.3 V
NOTE
When the alternator output is high and the value
displayed on the ammeter does not decrease
until 30 A, set the value to 40 A. Read the
value displayed on the voltmeter at this time.
When the value range is 40 A, the limit is max.
0.4 V.(11) If the value displayed on the voltmeter is above
the limit value, there is probably a malfunction
in the alternator output wire, so check the wiring
between the alternator “B” terminal and the
battery (+) terminal (including fusible link).
If a terminal is not sufficiently tight or if the
harness has become discolored due to
overheating, repair and then test again.
(12)After the test, run the engine at idle.
(13)Turn off all lamps and the ignition switch.
(14)Remove the tachometer or the MUT-II.
(15)Disconnect the negative battery cable.
(16)Disconnect the ammeter and voltmeter.
(17)Connect the alternator output wire to the
alternator “B” terminal.
(18)Connect the negative battery cable.
OUTPUT CURRENT TEST
Charging warning lampVoltmeter
Ammeter
Ignition switch
Alternator relayLoad
Battery
Engine-ECUAlternatorFR
L
S
G
+ -+-
B

ENGINE ELECTRICAL -Charging System16-6
This test determines whether the alternator output
current is normal.
(1) Before the test, always be sure to check the
following.
DAlternator installation
DBattery (Refer to GROUP 54 - Battery.)
NOTE
The battery should be slightly discharged.
The load needed by a fully-charged battery
is insufficient for an accurate test.
DAlternator drive belt tension
(Refer to GROUP 11 - On-vehicle Service.)
DFusible link
DAbnormal noise from the alternator while
the engine is running.
(2) Turn the ignition switch to the “LOCK” (OFF)
position.
(3) Disconnect the negative battery cable.
(4) Disconnect the alternator output wire from the
alternator “B” terminal. Connect a DC test
ammeter with a range of 0 - 100 A in series
between the “B” terminal and the disconnected
output wire. (Connect the (+) lead of the
ammeter to the “B” terminal. Connect the ( - )
lead of the ammeter to the disconnected output
wire.)
Caution
Never use clips but tighten bolts and nuts
to connect the line. Otherwise loose
connections (e.g. using clips) will lead to
a serious accident because of high current.
NOTE
An inductive-type ammeter which enables
measurements to be taken without
disconnecting the alternator output wire should
be recommended.
(5) Connect a voltmeter with a range of 0 - 20 V
between the alternator “B” terminal and the
earth. (Connect the (+) lead of the voltmeter
to the “B” terminal, and then connect the ( - )
lead of the voltmeter to the earth.)
(6) Connect the negative battery cable.
(7) Connect a tachometer or the MUT-II.
(Refer to GROUP 11 - On-vehicle Service.)
(8) Leave the hood open.
(9) Check that the reading on the voltmeter is equal
to the battery voltage.
NOTE
If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the alternator “B” terminal and the battery (+)
terminal.(10)Turn the light switch on to turn on headlamps
and then start the engine.
(11) Immediately after setting the headlamps to high
beam and turning the heater blower switch to
the high revolution position, increase the engine
speed to 2,500 r/min and read the maximum
current output value displayed on the ammeter.
Limit: 70 % of normal current output
NOTE
DFor the nominal current output, refer to the
Alternator Specifications.
DBecause the current from the battery will
soon drop after the engine is started, the
above step should be carried out as quickly
as possible in order to obtain the maximum
current output value.
DThe current output value will depend on
the electrical load and the temperature of
the alternator body.
DIf the electrical load is small while testing,
the specified level of current may not be
output even though the alternator is normal.
In such cases, increase the electrical load
by leaving the headlamps turned on for
some time to discharge the battery or by
using the lighting system in another vehicle,
and then test again.
DThe specified level of current also may not
be output if the temperature of the alternator
body or the ambient temperature is too
high. In such cases, cool the alternator and
then test again.
(12)The reading on the ammeter should be above
the limit value. If the reading is below the limit
value and the alternator output wire is normal,
remove the alternator from the engine and
check the alternator.
(13)Run the engine at idle after the test.
(14)Turn the ignition switch to the “LOCK” (OFF)
position.
(15)Remove the tachometer or the MUT-II.
(16)Disconnect the negative battery cable.
(17)Disconnect the ammeter and voltmeter.
(18)Connect the alternator output wire to the
alternator “B” terminal.
(19)Connect the negative battery cable.

ENGINE ELECTRICAL -Charging System16-7
REGULATED VOLTAGE TEST
B
BlueRed
Ignition
switchLoad
FR
L
S
GMB991519
Alternator
BatteryVoltmeterAmmeter
Yellow
Engine-ECU
Black
This test determines whether the voltage regulator
is correctly controlling the alternator output voltage.
(1) Always be sure to check the following before
the test.
DAlternator installation
DCheck that the battery installed in the
vehicle is fully charged.
(Refer to GROUP 54 - Battery.)
DAlternator drive belt tension
(Refer to GROUP 11 - On-vehicle Service.)
DFusible link
DAbnormal noise from the alternator while
the engine is running
(2) Turn the ignition switch to the “LOCK” (OFF)
position.
(3) Disconnect the negative battery cable.
(4) Use the special tool (Alternator test harness:
MB991519) to connect a digital voltmeter
between the alternator S terminal and earth.
(Connect the (+) lead of the voltmeter to the
“S” terminal, and then connect the (−) lead of
the voltmeter to a secure earth or to the battery
(−) terminal.)
(5) Disconnect the alternator output wire from the
alternator “B” terminal.(6) Connect a DC test ammeter with a range of
0 - 100 A in series between the “B” terminal
and the disconnected output wire. (Connect
the (+) lead of the ammeter to the “B” terminal.
Connect the ( - ) lead of the ammeter to the
disconnected output wire.)
(7) Reconnect the negative battery cable.
(8) Connect a tachometer or the MUT-II. (Refer
to GROUP 11 - On-vehicle Service.)
(9) Turn the ignition switch to the ON position and
check that the reading on the voltmeter is equal
to the battery voltage.
NOTE
If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the alternator “S” terminal and the battery (+)
terminal.
(10)Turn all lamps and accessories off.
(11) Start the engine.
(12)Increase the engine speed to 2,500 r/min.
(13)Read the value displayed on the voltmeter when
the alternator output current alternator
becomes 10 A or less.

ENGINE ELECTRICAL -Charging System16-8
(14)If the voltage reading conforms to the value
in the voltage regulation, then the voltage
regulator is operating normally.
If the voltage is not within the standard value,
there is a malfunction of the voltage regulator
or of the alternator.
(15)After the test, lower the engine speed to the
idle speed.
(16)Turn the ignition switch to the “LOCK” (OFF)
position.(17)Remove the tachometer or the MUT-II.
(18)Disconnect the negative battery cable.
(19)Disconnect the ammeter and voltmeter.
(20)Connect the alternator output wire to the
alternator “B” terminal.
(21)Remove the special tool, and return the
connector to the original condition.
(22)Connect the negative battery cable.
Voltage Regulation Table
Standard value:
Inspection terminalVoltage regulator ambient temperature_CVoltage V
Terminal “S”-2014.2 - 15.4
2013.9 - 14.9
6013.4 - 14.6
8013.1 - 14.5
WAVEFORM CHECK USING AN ANALYZER
MEASUREMENT METHOD
Connect the analyzer special patterns pick-up to the alternator
B terminal.
STANDARD WAVEFORM
Observation Conditions
FUNCTIONSPECIAL PATTERNS
PATTERN HEIGHTVARIABLE
VARIABLE knobAdjust while viewing the wave-
form.
PATTERN SELECTORRASTER
Engine speedCurb idle speed
AlternatorSpecial
patterns
pickupAnalyzer
B terminal

ENGINE ELECTRICAL -Charging System16-9
Voltage at
alternator
B terminal0.4
0.2
0
- 0.2
- 0.4
Time
NOTE
The voltage waveform of the alternator B terminal can undulate
as shown at left. This waveform is produced when the regulator
operates according to fluctuations in the alternator load
(current), and is normal for the alternator.
In addition, when the voltage waveform reaches an
excessively high value (approximately 2 V or higher at idle),
it often indicates an open circuit due to a brown fuse between
alternator B terminal and battery, but not a defective alternator.