Answer to Question #189748 in Mechanical Engineering for Yashwanth Kumar

Question

4. Explain the maintenance procedure and the various tests to be conducted on a lead acid battery of a vehicle. How do you carry over maintenance work on DC generator 

Answer 1

$\textsf{The maintenance procedure on a lead acid battery }$

1. Charge the battery fully, then let it rest for 4 hours.

If you’re testing an automobile battery, take the vehicle for a 20+ minute drive, then shut off the engine for 4 hours. For other types of lead acid batteries, charge them all the way before letting them rest for 4 hours.

While it takes a bit of time, this process of charging and then resting the battery gives you the most accurate measurement with the voltmeter.

2. Put on safety gear and turn on your digital voltmeter.

While you won’t be opening the battery cells to do this test, it’s best to play it safe and put on thick gloves, long sleeves, and protective eyewear. Remove any dangling jewelry as well. Turn on the digital voltmeter by pressing its power button and watching for the display screen to show “0.0”.

Buy a digital voltmeter at any auto parts or home improvement store, or online.

3. Touch the voltmeter’s positive probe to the battery’s positive terminal.

The digital voltmeter has 2 probes, one red and one black, connected to the voltmeter device. Place the metal tip of the red, positive (+) probe to the red, positive terminal of the lead acid battery.

If you’re checking a vehicle battery, you don’t have to disconnect the cables attached to the terminals. Just be sure you’re touching the actual battery terminal, not part of the cable attached to it. In some vehicles, you may have to lift off a red plastic cap to access the positive terminal.

4. Touch the voltmeter’s negative probe to the battery’s negative terminal.

Follow the same process as before, but this time with the black, negative (-) probe touching the black, negative battery terminal. Do this while continuing to hold the positive probe to the positive terminal.

Always touch the positive probe to the positive terminal first, then touch the negative probe to the negative terminal. If you connect the negative probe first and the positive probe touches any conductive material, you may short out the battery—which may damage it or, in rare cases, cause a dangerous explosion.

5. Check the display reading on the digital voltmeter.

Under normal circumstances, a 12-volt lead acid automobile battery should give a reading between 12.4 and 12.7 volts. Other types of lead acid batteries have varying ideal voltage readings, so check your battery’s product manual or look on the manufacturer’s website.

If your vehicle battery has a voltage reading below 12.4, it’s not holding a charge properly. In this case, either the battery itself is failing or it’s being drained by a “power parasite” in your vehicle—for instance, a map light you left on or a tablet you left connected to a charger in the vehicle.

Pull the negative and then positive probes away from the battery terminals once you’ve completed the test. This greatly reduces the possibility of accidentally creating a short circuit.

$\textsf{The maintenance procedure on a DC generator}$

The inspection maintenance of a DC generator installed should include the following items:

• Security of generator mounting
• Condition of electrical connections
• Dirt and oil in the generator — if oil is present, check engine oil seal. Blow out dirt with compressed air.
• Condition of generator brushes
• Generator operation
• Voltage regulator operation