Bench testing is an off-car operation to inspect starter functionality. For suppliers and buyers, it’s necessary for you to measure the original performance before installation. The testing directly matters to the starters’ quality and lifespan. You may rework and return the products, leading to delivery delay and even reduced customer satisfaction.
Preparation
With a complete set of tests, you can evaluate the starters accurately and diagnose the underlying starting problems, rather than testing a starter without removing it. The tests consist of voltage, rotating speed and current draw. Before starting the test, you need to prepare the following tools and information:
Tools and Instruments
·Goggles and gloves: Protect you against short circuits and other safety issues.
·Vise or other helpers: Secure the starter motor.
·Battery or other power source: A power supply to the starter motor.
·Jumper cables: Connect the battery to the starter.
·Jumper wire: Used to activate the solenoid.
·Voltmeter: Measure the initial voltage and the voltage under the load.
·Ammeter: Measure the current to observe its consumption.
·Tachometer: Measure the starter’s actual output speed during bench testing.
How to Bench Test a Starter Motor Step by Step
During the testing, pay your close attention to the clothing against getting caught by the starter gear. Follow the proper installation procedure: always connect the battery’s negative terminal first, then the positive.
How to Test a Starter with a Battery？
Step 1 Check the battery: A fully charged battery reads 12.4V~12.6V. Below 12.4V, the battery directly affects the accuracy of the test result. If the battery lacks energy, you should use a battery charger to power the battery first.
Step 2 Secure the starter with a vise: A high-speed spinning gear would move the starter. It may damage the starter and result in inaccuracy as well.
Step 3 Connect the battery’s negative terminal and starter case: Using the black negative jumper cable correctly and ensure it’s a complete circuit.
Step 4 Connect the battery’s positive terminal and the solenoid stud- B terminal: Using the red positive jumper cable properly and don't confuse B terminal and S terminal.
Step 5 Connect the meters: Voltmeter, ammeter and tachometer are individual instruments, so they can connect to the starter together:
·Voltmeter: Its negative leads to grounding (starter case) and the positive leads to B terminal.
·Ammeter: input to battery positive, output to B terminal.
·Tachometer: For the starter bench testing, an induction-type tachometer can avoid damaging the starter spinning at high speed
Step 6: Connect the jumper wire to the B terminal: the other end leads to the S terminal.
Step 7: Connect the jumper wire to the S terminal: Touch the other end of jumper wire to the S terminal of the solenoid, just last for 1~3 seconds. Or, it’s safer for you to use a remote-start switch.
Step 8: Observe and record: the reads change immediately when the current flows in the circuit.
How to Test a Starter with a Multimeter
A multimeter is often used to test the starter voltage rather than its current draw and rotation rating when simulating the actual operation. Because the multimeter can’t withstand the current flowing when the starter works. It’s efficient for you to prepare a voltmeter, ammeter and tachometer to complete the comprehensive testing.
How to Bench Test a Starter without a Solenoid
A starter without a solenoid is generally used in older vehicles. When you’re testing, the battery negative terminals also connect to the grounding. One end of red jumper cables leads to the input terminal ( is the B terminal in the starter with a solenoid ). Once the red jumper cables touch the input terminal, the starters engage and the gears spin at a high speed.（Also it’s safer to use a remote-start switch)
Normal Starter Test Result
When a car starter functions normally, the engagement and disengagement perform fast within 3 seconds. Also, you can see the gears move out and in to start the “engine” and all readings are as follow:
Normal rotation speed: 3,000-5,000rpm
Normal voltage under the load: 10-11V
Normal current under the load: 150-250A
Signs of a Faulty Starter and the Causes
If the car starter exceeds or fails to meet the normal readings above, you often notice a loud clicking or slow spinning. Even worse, the starter has no response to the signal.
There are some common reasons:
· Short circuit and aged insulation : Flows the current more than the common.
· Bearings wear: Cause the slow rotation.
· Poor contacts: Carbon brushes can't conduct the current effectively and the contacts melt.
· Damaged gears: Gears can’t engage properly and cause a vibration and loud clicking
· Clutch pulley slipping: Fail to drive the gears but the starter spins freely.
Whatever you diagnose the root cause during the bench test, the starter would perform worse in the actual environment.
How to choose the starter suppliers based on the testing result
From the results, you can evaluate the production quality and quality control capabilities. As a buyer or supplier, you can make a careful decision to partner with the starter (parts) suppliers or not. Purchasing the starter parts for replacement is also an acceptable solution.
Conclusion
To enable the starters to function optimally, you simulate the real-world environment and analyze every aspect before sales and installation. This would assess the issue of returns and improve quality control.
FAQ
How to Test a Starter with a Power Probe
Follow step 3 and step 4 to connect the battery. Then the power probe adds extra power to the S terminal, driving the flywheel to engage the gear.
How to Bench Test a Starter Solenoid
You can use a multimeter to test a starter solenoid to check it for potential problems.
