Starter motors and alternators have continued to evolve alongside the vehicles that they serve. This means that alternators become ever more powerful (typically 100 amps) and starter motors are now being designed for "start/stop" technology bought about by the need for ever more economical and environmentally friendly vehicles. With this technology the engine stops when ever the vehicle comes to rest but re-starts instantly when the accelerator is pressed. In a town environment the benefits could be huge.
But developments continue with the starter and alternator being combined and engineered to recover energy when braking, this energy is then re-used when the vehicle accelerates again. To achieve this the combined motor and generator is integrated into the engine or gearbox, whilst the stored energy waits to assist the engine whilst accelerating.
It is anticipated that using both of these technologies savings of 15% should be easily achievable.
But even today’s vehicles are using technology to a greater extent, alternators are now often part of a smart network. In the Alternator section of this site we have explained how the traditional unit was controlled, well things are changing and more and more the alternator and battery are monitored by the vehicles computer that acts as an energy broker for all of the vehicles systems. In effect this means that the alternator charges the battery to the optimum level, but if electrical demands start to exceed supply then the vehicle will start shutting down non-essential functions (heating fan, interior lights etc) via the CAN* system. So it is quite possible that the first thing you know about an alternator or battery fault is when the heater fan suddenly switches off.
*Control Area Network.
Some vehicles now have water cooled alternators.
An average car carries out in excess of 2,000 stop/start cycles in a year
Some alternators are fitted with free wheeling pulleys to help damp out the changes in engine speed that can damage drive belts.