THE CAR’S CHARGING SYSTEM

As the battery deteriorates, due mainly to internal corrosion and sulphation, its internal resistance increases. Unfortunately, this fools conventional car alternators into thinking that the battery is charged fully, when it is not. The result is undercharging, which encourages more intense sulphation and increases the rate of deterioration. This assumes, of course, that the alternator is neither undercharging nor overcharging and that its drivebelt (part of the front end auxiliary drive FEAD system; see page 38) is unworn and tensioned correctly.

If you notice the battery voltage on a non-stop-start vehicle creeping above 14.8V in normal temperatures with the engine running, Yuasa advises that the charging system might be faulty and requires attention. The battery will need to be tested also, for any signs of damage due to overcharging. This advice does not apply to smart alternators.

On vehicles that are equipped with conventional fixed voltage alternators with internal regulators, a DIY test procedure can be performed using a basic multimeter, as outlined below.