Driving/Charging Operation (Alternator)

The alternator charges the starter and system batteries in parallel. The starter battery is disengaged if now the voltage of the starter battery is greater than the alternator voltage. Only the system battery is charged. If now in driving operation the system voltage drops below 9 V +/- 0.5 V, the starter battery is cut in to support the electrical system. This can result in both batteries discharging.