Testing Car Battery

There are many different tests to check the battery's condition, the simplest is checking the voltage using a voltmeter, simply:

1. Connect the voltmeter positive to the battery positive terminal(not clamp) and voltmeter negative to battery negative terminal.(figure 1)

   Fig 1 : Battery terminal test

   
   











2. Although its acceptable to have at least 9.6v, recharge the battery until it reads 12v to 15v.
3. To check if the battery clamps are clean, repeat the test above on the battery clamps (figure 2) , the difference should be less than 0.1volts . If the difference is more than 0.1Volts , use a brush to clean the terminals and clamps using a mixture of baking soda and water , then rinse with water .

Fig 2 : Testing the battery clamps , the
difference should be less than 0.1Volt

Note on Multimeters : To check the battery using multimeter turn the knob to value close to 12v in the DC voltmeter section (20v in my case).

Note: Car batteries can become sulfated (sulfate coating lead plates) when undercharged, which make it a bad idea to place a load on the battery when the car is turned off.

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