We have one time or another suffered the inconvenience of a flat battery.. It is frustrating indeed.

We find that ..

How can we best avoid such unpleasant situation without incurring high costs?...

Firstly, we must understand the battery's role in our car.

In short, we need battery power to START or OPERATE our car's onboard electronics.

The activity of the alternator or dynamo is governed and controlled by ECM (Engine Control Management) or PTM (Power Train Module).

Vehicle Charging System	Battery Power Management

• Modern cars have a float current measuring between 11.80V to 14.99V generated by the alternator when the engine is in operation or car is in motion. This current is supplied to all vehicle onboard electronics for operations and to charge the battery.
  
• Voltage supplied is reduced when the car reaches cruising speed where engine load is relatively low.
  
 
• This particular mode is featured in most Asian (ie. Japanese, Korean) makes in order to enhance fuel efficiency as less fuel is consumed when the alternator load is reduced. This is known within alternator design as VARIABLE LOAD RESPONSE.
  
  
• Alternator function is governed by the ECM. When the Battery Current Sensor + Battery Temperature Sensor signals are relayed back to the ECM and compared to engine load parameters, the ECM adopts the look up tables and controls the output functions of the alternator.
  

  Battery Current Sensor

• Due to emissions control and the need for better fuel consumption, post-2002 car models are designed with IDLE STOP SYSTEM or CHARGE CONTROL function in the vehicle charging system as explained above.

* You will recognise the idle stop system / charge control fitted vehicle by the STAR rating emissions sticker found on the rear panel of the vehicle