Part of Lesson Plan: **Perform a battery, starter, charging system test using the VAT-40 (updated) by Eli Jaramillo
Activity Overview / Details
During the next hour, you'll be demonstrating the use of the VAT on a vehicle to test the starting and charging systems. The suggestion here is to split your class:
- Half will accompany you to the lab where you'll use a lab vehicle to demonstrate load testing of starting and charging systems.
- The other half will remain in the classroom where they'll write essay-style answers for ASE-prep questions pertaining to testing of battery, starter, and charging system. Give them questions out of your classroom textbook.
- After your lab demonstration with the first group, you'll rotate the groups and take the second group out to demo the same thing. The first group will rotate back into the classroom to complete the same questions on battery, starting and charging system testing.
For your lab demo, on a shop vehicle, you'll be be cranking the engine over with the ignition system disconnected. While cranking, the starter should not draw more than a specified amount of amps. Excessive amps during this test could mean starter internal drag or starter circuit resistance.
Classroom group of students:
- Whiteboard: Write the questions for the classroom student assignment on the board.
- The assignment should be a group of questions pertaining to testing of battery, starter, and charging system. ( from your classroom textbook) Choose enough questions to take them 30 minutes, enough time for you to complete the demonstration. The questions should require the students to respond with written answers.
Lab group of students:
- Student Worksheet: Testing a Starter
- One vehicle with all systems working
- VAT tester (Volt-Amp Tester)
- Instructions for that tester if needed
- Take half the class out to the lab with you.
- Hand out worksheet Testing a Starter.
- Use the same worksheet as a guide for your lab demonstration.
Pre-checks/set-up on your demo vehicle:
Under your supervision, have select students perform the steps below.
- Turn off all switches, lights, accessories, make sure all doors are closed.
- Make sure the battery is in good condition. Perform a visual inspection. Check for cracks, corrosion, other damage.
- Test battery ‘open circuit’ voltage. If less than 12.4 volts charge the battery.
- Disable the vehicle ignition system. If in doubt, refer to the vehicle wiring diagram for the correct ignition system wire to disconnect.
Tester set-up on demo vehicle:
- Turn the large LOAD control knob fully counter-clockwise.
- Set TEST SELECTOR to the #1 STARTING SYSTEM.
- Turn voltage selector switch to 18V.
- Use the Zero-Adjust control to adjust the AMPERES ammeter to read ZERO.
- Connect the large alligator clamp tester leads, red to battery positive, black to negative.
- Clamp the green inductive ammeter pickup around the negative vehicle battery cable.
Perform starter test:
- Crank the engine over for about 5 seconds.
- Read the ammeter. The amperage draw should be approximately the following: V-8 about 200 amps. Six cylinder about 150 amps. Four cylinder abut 125 amps.
Your reading: _______ Within spec? ________
Based upon results from the above test: Ask the class for their opinion: Within spec?
Materials / Resource
- Worksheet: Testing a Starter [ Download ] Worksheet used by students in the lab.