When a car refuses to start, most people attribute the problem to the starter, which is a good start to diagnosing the problem. However, the battery might also be a contributor to this issue and should be the first place to look when troubleshooting.
This way, you might save yourself from replacing a starter in good condition. The amount of current a starter draws is dependent on the state and voltage of the battery. The current drawn might also be affected by the condition of the starter and circuits.
- What Causes a Starter Motor to Draw Too Much Current?
- How Do You Test a Starter Current Draw?
- Should a Starter Always Have Power?
- How Many Amps Should a Starter Draw?
- What Does the High Starter Current Draw Test Usually Indicate?
What Causes a Starter Motor to Draw Too Much Current?
There are several possible reasons responsible for a high current draw. These include engine problems, a faulty battery, circuit issues, and faulty starters.
01. Low battery voltage
This can be understood by looking at the formula of power. Power is the product of voltage and current draw; hence, the lower the voltage, the higher the current. Therefore, if the voltage supplied by the battery is low, the starter compensates by drawing a higher current.
A few things can cause low battery voltage, and it’s important to check for all of them before replacing your battery.
First, make sure that all of your connections are tight and corrosion-free. A visual inspection of the terminals should quickly tell you the condition of the battery connections.
Next, check the voltage at the battery itself using a voltmeter. If it’s below 12 volts, your battery is most likely dead and needs to be replaced.
Lastly, check the voltage at the alternator. If it’s low, the alternator may not be charging the battery correctly.
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02. Short circuit of the starter motor
A short circuit of the starter motor can occur for a variety of reasons.
The most common cause is when the ignition key remains in the start position for far too long, leading to overheating of the starter and damage to the internal insulation.
A faulty solenoid is another possible cause for a short circuit of the starter motor.
To check for a short circuit of the starter motor, first, make sure that the battery is disconnected. Then, check the continuity of the starter solenoid’s windings using a multimeter. If there is no continuity, then the solenoid is defective and must be replaced.
03. Jammed starter motor
If the starter is wedged or stuck, more current is drawn. Since running starter motors use less current compared to when stalled, more current is drawn. The starter motor could become stuck if the pinion teeth do not lock.
04. Faulty starter
A bad starter might draw too much current from the battery and might even lead to battery drainage if not noticed early.
How Do You Test a Starter Current Draw?
You will need specific tools (ammeter and voltmeter) to complete the setup that will help you determine how much current your starter draws. Before starting the test, check the state of your battery.
Ensure it is in good condition and fully discharged to ensure accurate results. Examine circuits as well. Before beginning the test, ensure the engine is at the normal operating temperature because a cold engine will draw more current.
- Attach the voltmeter to the negative and positive terminals of the battery to measure the battery voltage.
- Connect the clamp-on ammeter. You could use an electrical system tester instead of an ammeter or a voltmeter.
- Disconnect the ignition and fuel to prevent the engine from starting during the test.
- Then monitor the voltmeter and ammeter simultaneously as you crank the engine.
- The engine should not be cranked for more than 10 to 15 seconds, and there should be a 2-minute break between each crank to allow the starter to cool.
You might need your car’s manual for this process to ascertain what the normal current draw should be. The current draw measured should either be lesser than or at the normal amount, while the voltage drawn should be around 9 to 10 volts depending on the temperature.
Related content: Can a Bad Battery Cause Engine Hesitation?
Should a Starter Always Have Power?
Yes, a starter should always have power because it needs a high current to turn over the engine. This current can only be provided if the battery has sufficient power. A discharged or weak battery cannot power the starter with enough current to turn over the engine.
This is one of the reasons some people attach a car without starting the starter. Meanwhile, it is the battery that is the cause of the issue. The car’s battery and the starter are linked in such a way that an issue with one can lead to potential risks in the other.
How Many Amps Should a Starter Draw?
This will depend on the car’s engine, as a bigger engine will require more amps to start. To find exactly how much amps your car uses when starting the engine, check your vehicle’s owner’s manual or a repair manual.
The amount of power your starter uses will also depend on the environmental conditions. On a frosty morning, you will surely get higher readings compared to a sunny afternoon.
A v8 will draw up to 600 amps when starting the cool off to 150-200 when running, while a four-cylinder vehicle will surge to 200-250 and taper off to 80-100 amps.
What Does the High Starter Current Draw Test Usually Indicate?
When performing a starter current draw test, a high current draw usually indicates a faulty starter or other likely engine problems. A high current draw might also occur if the test is not conducted correctly. If the engine is not at normal running temperature before the test, the current draw might be higher than normal.
If the bushings or bearings inside the starter are worn, the result could be a high current draw because this issue would displace the alignment of the magnetic field of the starter.
Please note that the bigger the engine, the higher the current draw; hence, do not compare the current draw of one car to the other. Instead, consult your car’s manual to know the normal current draw of your vehicle.
Here are some questions one might have when dealing with a problematic car starter.
What Does a Low Starter Current Draw Test Usually Indicate?
When performing a starter current draw test, a lower than normal current could be caused by high resistance in the starter circuit. High resistance could be caused by corroded connections, loose connections, or carbon accumulation in the solenoid or relay contacts.
What Should Be Disabled Before Performing a Current Draw Test?
The ignition and fuel systems should be disabled before a current draw test to prevent the engine from starting.
Can a Bad Starter Drain Your Battery?
Yes, a bad starter can drain your battery. If you do not notice this quickly, you might drain your battery faster than you might imagine, especially when you keep trying to start the car with a bad starter.
If you turn your ignition switch and your car clicks but does not respond, you might have a faulty starter or a battery issue on your hands.
Due to the connection between the starter and the battery, it is possible to take a battery issue for a starter issue and vice versa. In either case, the first place you would like to start your troubleshooting is at the battery before you move on to the wire connections and the starter.
If your battery and circuit tests are favorable, you might need to perform a starter draw test to confirm the problem.