Dealing with random engine shut-offs? It might be your car's stop-start system

You've just bought your first car - the culmination of the hard work and hard-earned money. Finally, you can enjoy the convenience of coming and going as you please. There's no need to book a ride or wait for public transport to arrive.

Now, your drives are going smoothly, except for one odd thing: The engine seems to randomly switch off when your car is stationary.

It feels like something has gone wrong or is about to go terribly wrong. But hold on, don't head to the workshop yet because your car isn't broken! It's just the stop start-system and we'll explain how it works.

It's a fuel-saving function

As its name describes, a stop-start system helps reduce fuel consumption by switching off the engine when the car is stationary. So, when you're stopped in traffic or queueing to enter a carpark, the car turns off the engine.

The engine is automatically restarted once you release the brake pedal. In some cars, the engine may also restart once the accelerator pedal is depressed.

Now, we know what you're thinking. This function is highly irritating because the engine keeps "dying" and restarting. Worse, the shudder/judder that accompanies this process makes the drive feel uncomfortable.

However, the fuel used to restart the car is less than what your car would burn while idling. Over time, the amount of fuel saved will add up, especially if you typically drive during peak hours. That's something to think about considering that at time of writing, 95 RON is nearly $3 per litre!

Are there other downsides?

Apart from the shudder you feel when the car re-starts, the cabin also becomes warm since the air-con compressor isn't working while the engine is stopped. On especially hot days, this is very uncomfortable since the air-con only recirculates the existing cabin air.

The other disadvantage to this system is that your car needs to use more expensive batteries. By their nature, stop-start systems require the use of an Enhanced Flooded Battery (EFB) or Absorbent Glass Mat (AGM) battery.

We'll tackle the difference between an EFB and AGM battery in another story, but what you should know is that both types are more expensive than conventional (lead-acid) batteries, with AGM batteries costing even more than EFB ones.

Smoother stop-start systems

Not all stop-start systems are clunky. Cars equipped with 48-volt mild hybrid systems, for instance, have stop-start systems that are much smoother.

In fact, restarts are so seamless that if you weren't paying attention, you might not even notice the system in action. The 48-volt system also allows some cars to "coast" or "sail". This means when conditions are right, the engine switches off while the car is cruising. Don't worry, stepping on the accelerator immediately re-starts it.

Stop-start systems help reduce fuel consumption and tailpipe emissions, which is why more and more cars today have this feature. If it's really a bother, you may be able to switch it off. But before you dismiss it for good, give it some time because you might just appreciate its benefits.

ALSO READ: Car engine decarbonisation 101

This article was first published in sgCarMart.