Starter Motor Bench Testing and Repair

Remove over Safety & Resource
Student must wear overalls and steel cap work boots at all times

Resources:
Starter motor test bench, 6-12 volt power supply, digital voltmeter, amature growler, 45 volt test light, Suitable tolls and equipment to enable starter motors to be dismantled and repaired, preengaged starter motor, manufacturers specification if possible.




This is the test and measurements taken to perform on the Starter Motor.

First we start with:

• No Load Test
• We test No Load Voltage
• Test No Load current

Manufacturers Specifications

• No Less that 11 Volts
• 30-50 Amps
• Results
• 11.5 Volts
• Nil

 To Disassemble the Starter Motor I have included the following steps:

• Mark along two end housing, it helps when you assemble component
• Remove M Terminal wire from Solenoid
• Remove the Solenoid
• Remove commutator end house (and failure in the major damage to the brush or field winding)
• Remove brushes and brush plate
• Remove field coil housing
• Remove shift fork
• Remove armuature
• Remove over running clutch

Visual

• Crack
• overheating
• Burning
• Physical Damage in coil winding
• poling

All Visual Inspection had passed

- We performed Ground Circuit Test
- We used multimeter to test commutator segment and the armature core on armature ground and the results O (zero) and it is serviceable.
- We did a test on continuity circuit on Ohmeter to check continuity between commutator segments and probe the around on each while moving and results come 0.5ohm and it is serviceable.
- Commutator Measure to check the mica undercut depth.  We use the Vernier Caliper to measure this.
- These are the manufactures specifications

• minimum diameter - 26.8mm-31mm
• mica undercut - 0.7mm-1.0mm

The Results
30mm - minimum diameter - yes it is serviceable
1.0mm - mica undercut - yes it is serviceable



BRUSHES
The brushes are removed from the Starter Motor and measured according to the Manufacturers Specification requirements.   If the bruchess ready under 5mm they will need to be replaced.
Findings:

• 14mm
• 16mm

CAR STARTER MOTOR CIRCUIT ASSESSMENT
The vehicle we have used on this assessment is a Nissan Sentra 1992

1. We inspect the vehicle to ensure there are no damages i.e loose wiring
2. Check if the vehicle is a Manual or Automatic
3. Check if the vehicle is equpiied with a power source device

PRELIMNARY CHECK BEFORE CARRYING CIRCUIT VOLTAGE DROP

1. De-activate ignition and fuel injection system
2. Checked the battery for service ability
3. selected the right range on the meter

CHECK BATTERY AVAILALE VOLTAGE UNDER CRANKING RESULT ON CRANKING VOLTAGE- 10.8V

1. Voltage drop positive side of the circuit
2. spec less than = 0.20volts > volt drop=0.06
3. voltage drop on Solenoid
4. Spec less than = 0.10volts > volt drop = 0.10
5. Votage drop onearth side of the circuits

Spec kess = 0.20v > volts drop 0.12
Maximum allowed = 0.50 > Total volts drop 0.28
Specification = 125 > 150amps
Starter Draw = 079.9

All the reading and checking we have performed on the vehicle circuit was inside of the specification reading and the circuit was in good condition.

CAPACITOR
Calulation on how fast the capacitor should charge.

1. The following calculations are used to determine how fast the capacitor can charge i.e Calculated time, seconds and Capacitance UF into Resistance x5 to get the calculations.

CAPACITANCE	CAPACITANCE	X	RESISTANCE	X	5	CALCULATED
(µf)	(F)		Ω			TIME
						Seconds
10	0.00001	x	1,000	X	5	0.05
1	0.000001	x	250,000	X	5	1,250
100	0.0001	x	10,000	X	5	0.005
300	0.0003	x	4,500	X	5	6.75

                                                      

CALCULATE RESISTOR SIZE
The follwing calculations are done on four resistors, to determine this we check the number of resistors or the UF and then find the identifcation x5 to find determine the answer.  e.g:

CAPACITANCE	CAPACITANCE	X	5	Answer
(µf)	(F)
22	0.000022	X	5	0.00011
100	0.001	X	5	5
0.47	0.0000004	X	5	0.000002
22	0.000022	X	5	0.00011

MONITORING CAPACITOR CHARGE TIME VERSE VOLTAGE
First we bridge the wire and then remove the bridge to count every 10 second up to 220 seconds in 3.7minutes to see the charge.  The following is readings:

10	90	20	1.79	30	2.77
40	3.74	50	4.45	60	5.69
70	6.57	80	7.24	90	7.8
100	8.4	110	80.82	120	9.2
130	9.6	140	9.9	150	10.15
160	10.4	170	10.6	180	10.8
190	10.99	200	11.15	210	11.32