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How to test car battery at home

How-to-test-car-battery-properly

It may be useful to know how to check car battery properly. It explains useful car maintenance tips to check battery voltage, to check battery terminals and determine battery electrolyte level. In addition, these test gives you information about the operating status, the state of charge and also the status of the alternator.

Testing a Car battery is essential before considering replacement. Indeed, if the problem comes from the alternator, the replacement of the battery may be unnecessary. Especially, if battery maintenance instructions are strictly followed, these tests may save you from needless battery change.

Procedure for testing a car battery

Here are the steps to properly check car battery and find out if it is out of order, recharge or replace.

Caution  : Remove rings, gourmet and any metal object that could cause a deadly short circuit if it came in contact with the plus and minus of the battery!

Test the battery charge

Begin by removing any metal objects (curb chain, ring, cuff, etc.) or you risk exposing yourself to a deadly short circuit.

If your car starts

To test the charge level of a battery, use a multimeter:

  • Choose the voltmeter and direct current mode of the multimeter (the symbol resembling the sign “=” and not the alternating current wave).
  • Select the 20 V position.
  • Connect the red multimeter cable to the “+” terminal of the battery.
  • Connect the black multimeter cable to the “-” terminal on the battery.
  • Start the engine &  accelerate until it reaches about 2000 RPM.
  • The measured voltage must be greater than 13.2 Volt:
    • If the voltage is higher than 15 V, the battery is overcharged. The voltage regulator is probably out of order.
    • If the measured voltage is less than 13.2 V, the problem probably comes from the alternator.

If your car does not start

Carry out the same operation, but with the help of another vehicle:

  • Park the cars close to each other and head spade, but do not touch each other.
  • Leave the starter car on.
  • Connect the black cable to the “-” of the healthy battery and then to the “-” of the battery to be serviced.
  • Then, connect the red cable to the “+” of the battery pack and then to the “+” of the battery to be serviced.
  • Then, start the car to troubleshoot.
  • Roll for several minutes to recharge the battery.

For detailed information visit methods of starting and recharging dead car battery.

Finally, perform the test using the multimeter as explained above.

Warning: Right connections is vital!. An inversion may cause dangerous sparks. If you are not sure please check how to jump starts a car.

Checking the acid level

Acid or Electrolyte level can determine the charge of the car battery.  The lead metal plates and cells of batteryadding water check car battery must be immersed in mixture of water and acid called electrolyte. The electrolyte level must exceed the plates by about 1 to 1.5 cm.

Simply remove the plugs to check the electrolyte level. If it is below the above stated level, simply add distilled water in it.
Caution! Never add sulphuric acid to used battery.

Above operation in not possible on Maintenance free batteries. In such batteries, plugs are sealed and liquid electrolyte is replaced by gel

Testing the car battery voltage

Again, be sure to remove any metal objects (curb chain, ring, cuff, etc.) or you risk exposing yourself to a deadly short circuit.

For this test, your engine must be cold and at standstill:check car battery voltage

  • Select the meter’s voltmeter mode.
  • Select the 20 V position.
  • Connect the red multimeter cable to the “+” terminal of the battery.
  • Connect the black multimeter cable to the “-” terminal on the battery.
    • If the measured voltage is 12.6 V, everything is normal and the  battery is charged properly.
    • If the measured voltage is between 12 and 12.3 V approximately, battery is discharged. Recharge it.
    • 13V or above voltage indicates that overcharged battery. Mostly it is due to the problem in charging circuit.
    • If the measured voltage is about 10.6 V, your battery is probably HS, it must be changed.

Check the color of the plugs

The caps of a battery are a good indicator of its condition:

  • Remove the plugs with a screwdriver.
  • Check their color:
    • If you observe a black plug, the reason is probably a short circuit and battery is HS.
    • In addition, black plugs also indicate overcharged battery and the problem comes from the charging circuit.
    • If the plugs have their original color, the battery is good, but may be discharged.

Regular auto maintenance and small trouble shooting tests help in keeping your car in good condition avoiding costly repairs.

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