Honda Worldwide | Technology Close-up



	Precise control of charging and discharging the battery When the starter is unable to crank the engine due to a discharged battery, a vehicle equipped with an “idling stop system”, will not start. To prevent discharging of the battery, even when operated in traffic, the charging capacity for the “idling stop system” is set higher than usual.

Charging system designed to prevent discharging of the battery

It is necessary to increase charging capacity for an “idling stop” vehicle compared to a vehicle that with idling. This is necessary because the battery is not charging when the vehicle is stopping for a traffic signal etc.
An “idling stop” vehicle cannot restart if the battery is discharged and the starter motor cannot crank the engine. To cope with the aforementioned, the charging output from the ACG starter in the “idling stop” vehicle is designed to such a level that prevents the battery from discharging even when operated on congested roads using the “idling stop system”.

Reduced friction from the power generation

When an “idling stop system” is applied, due to lack of power generation during stopping, the electrical loads, such as the headlamp, draw a considerable amount of power from the battery when stopping. Power consumed from the battery during stopping is quickly recovered from the alternator when the engine revolutions increase and the power generation starts. A considerable amount of mechanical energy from the engine must be consumed for the power generation by the alternator, resulting in weak vehicle acceleration.

Friction from power generation

The charging voltage at the time of start is regulated.

To reduce friction from power generation, and to ensure strong vehicle acceleration when equipped with the “idling stop system”, the charging voltage is lowered to 12 volts from the normally regulated voltage of 14.5 volts for a prescribed period of time. In doing so, the battery is not charged during vehicle acceleration, and charged only during constant speed or deceleration. Charging during deceleration is especially effective because it means an efficient use of energy.

Charging voltage regulation