If a car starter is extremely hot, it’s highly possible that it’s drawing too many amps too.
So, what causes this?
Read on to find out why the car starter may be drawing a high current.
How Many Amps Should a Starter Draw?
The current drawn by a starter varies by starter design (power rating) and can range from 60 amps up to 200 amps when starting the car (estimates).
This assumes a starter power rating of between 0.8 kW to 2.2 kW.
To confirm the expected car starter draw, consult the car’s repair manual.
The actual amp a car starter draws
This depends on the battery voltage, starter power rating, and battery voltage.
A car with a 1.6kW starter with a battery voltage of 12V draws about 133 amps when starting.
On the other hand, if the battery is fully charged at 13.6 V, the starter amp draw will be about 118 amps, 11% lower.
Tips to Measure a Car Starter Amp Draw
What you need: a voltmeter, a current meter- the clamp-on type and the car owner’s manual.
- Connect the digital voltmeter probes to the positive and negative terminals of the battery
- Let the ground wire from the battery negative terminal run through the clamp for the current meter before connecting to the car’s ground (chassis).
- Start the car and run it at about 200 RPMs while monitoring both the current draw and the voltage.
The rated current draw mainly depends on the starter power rating and voltage. Refer to the car repair manual.
Check that the starter motor current is at or less than that specified in the car repair manual.
Expect the battery voltage when the car is starting to drop to as low as 9.6V or higher at 68°F – 77°F.
What Causes a Car Starter to Draw Too Many Amps?
If the car starter is pulling too many amps, it is likely that the starter motor is faulty. This may be caused by:
1. Starter motor is restricted and not able to rotate freely. This may be because there’s an object that’s jammed and locking the starter. Perhaps it is an issue with the flywheel or car engine?
Contact a qualified auto mechanic to support you.
2. There’s a short in the starter motor winding. A damaged starter with broken-down insulation will result in reduced winding resistance and it pulling too much power too.
3. Worn bushings and brushes. A higher than expected current draw by the starter may also be because the bushings and brushes are worn and need to be replaced.
A High Amperage Draw when Testing a Starter- What Causes This?
If the current draw by the starter is too much, it’s quite likely that it’s faulty. There may be a short in the motor windings or the bush or brushes are worn too.
If the starter’s current draw is higher than that specified in the car owner’s manual then it’s quite likely that it is defective.
Possible causes of an excessive current draw by the starter are a jammed or stuck starter motor, worn bushings or brushes, or a shorting starter motor.