Troubleshooting and checking the power supply system
Check battery, starter, and alternator leads and cables for loose, corroded, or damaged cable leads and wiring.
Check the charging current and charging voltage of the alternator.
Check that the alternator freewheel pulley is functioning properly. Raise the engine speed to 3000 rpm - without any additional consumers of electricity. Turn off the engine. Make sure the alternator clutch continues to rotate longer than the engine. In cold weather, the battery charge lamp in the instrument cluster may come on for a few seconds after starting. This is because the freewheel takes extra time to heat up the bearing grease. A solid battery charge light may indicate that the freewheel is not locked to the alternator rotor shaft. Check accessory drive belt tension. Check belt for wear (see section «Engine and control systems»).
Measure the power consumption at quiescent voltage.
Current measurement at rest (by car)
Open the hood.
Connect a multimeter between the negative wire in the harness and the negative battery terminal. Start with a measuring range of 10 A. Continue in a decreasing direction until a suitable measuring range is found. If the quiescent current is 10 mA higher than the maximum allowed, install a larger capacity battery in the car. If a high-capacity battery is already installed, find the main components of power consumption at rest. This can be achieved by measuring the quiescent voltages at the moment when the consumer fuses are removed one by one.
Then measure the quiescent voltage with the car locked and the alarm on. This will require a length of wiring long enough to take a measurement with the car locked, the hood and the alarm on. The wiring must be connected between the negative wire and the negative battery terminal. Connect multimeter.
Open the circuit after one minute to allow current to flow through the multimeter.
Calculation of the maximum allowable quiescent voltage.
Set the capacity of the battery in the car to calculate the maximum allowable quiescent voltage.
Formula: * Ah/504 h/4 = I mA (* = battery capacity, I = quiescent current).
For example: capacity / 3 weeks * 25% = rest voltage 65 Ah / 504 h * 0.25 = 32.2 mA.