Car Battery Testing in Al Taawun

The test has four parts. Resting voltage comes first: a healthy, fully charged battery sits near 12.6 volts, 12.2 is about half charged and anything near 12.0 is flat. Voltage alone can mislead, so a conductance tester is clamped on next. It sends a small signal through the plates and reports cranking power in CCA, cold cranking amps, which is compared with the rating printed on the label. A battery showing 12.5 volts but only half its rated CCA will fail on the next hot afternoon. The tester also reports internal resistance and a state-of-health percentage.

Then the engine is started and the charging system is measured. Most cars should show roughly 13.8 to 14.7 volts at the battery with the engine running. A lower figure with the lights and AC on points to the alternator or its belt, and a higher one to a faulty regulator. If battery and alternator both pass but the car still goes flat when parked, the technician puts an ammeter in line and waits for the car's modules to go to sleep. A draw above about 50 milliamps means something is staying awake, often an aftermarket alarm, tracker, dashcam or boot light.