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Flat Battery?

We'll find out why

Faulty or flat batteries are one of the most popular callout problems for our patrols. Stop-start or short journeys can deplete batteries if they are not regularly recharged. There are a few things you can do to prolong the life of your car's battery, but we can also help.

If you call us out because your battery is flat, we won't just jump-start your car, we'll check the battery's condition and try to discover how it became flat. The test procedure we use has been independently checked by other motor industry professionals.

If your battery fails the test, you should replace it as soon as possible – it may struggle on for a short time, but it will let you down again soon.

AA standard approved battery test procedure

  1. The patrol will attach a multimeter to your battery to check the level of charge.

    Any reading over 12.2 volts will indicate that the battery is in a condition that will allow the test to continue. (If the voltage is below 12.2 volts the patrol will start your vehicle and run the engine for about five minutes to recharge your battery.)

    At the same time the patrol will carry out other checks to confirm the output from the alternator.

  2. The next part of the test will determine the ability of the battery to meet the (loaded voltage) demands of the starter motor.

    This is a critical part of the test and the patrol will be looking for a voltage that should stabilise at a lower level than step 1 and remain relatively constant over a 15-second cranking period.

If the voltage fails to stabilise and continues to drop throughout the cranking period, the battery needs replacing. Although the car may start now, starting your vehicle in the near future cannot be guaranteed. In this situation we advise you to replace the battery as soon as possible.

If the test confirms your battery is in a serviceable condition, the patrol will carry out more diagnostic tests to locate the fault in your vehicle.

The battery test

  1. The patrol will measure the battery voltage.
  2. If the battery voltage is too low, the patrol will recharge the battery for about five minutes.
  3. The patrol will then test your battery by cranking the engine.
  4. The readings on our meter will inform the patrol whether the battery passes or fails.