How automakers tackle automatic start-stop without adding wear and tear – Jalopnik

There is no doubt that automatic start-stop technology delivers tangible fuel economy benefits. A study by the Society of Automotive Engineers (SAE) found that drivers could potentially see a 7 to 26% improvement in fuel economy. However, this depends on the use, hence the wide range. The longer you idle during your commute, the more likely you are to witness better fuel economy.

But perhaps the biggest misconception surrounding automatic starting and stopping is the increased wear and tear on the engine/components. While there is some truth to that (although it’s not as dramatic as you might think), it’s worth pointing out that cars with the technology built in are designed to address these issues. Understand that the car’s battery and starter motor are major players here, as are the control modules and alternator. Manufacturers are fully aware of the additional stresses that some of these components will experience over the life of the vehicle.

Take the starter for example. Denso, which supplies starter motors to several car manufacturers, has three different versions, specifically designed with automatic start-stop in mind. You have a fairly traditional starter, with improved ring and pinion operation for less wear; a tandem solenoid (TS) version that reduces the required electrical load; and a “permanently engaged” design that is quieter, faster and more efficient between stop-starts.

Some cars use an integrated starter-alternator design, which often includes a separate control module to run programs that protect the system from the increased stress of repeated stop-start cycles. Technically you could say that a start-stop alternator is different to what you would find elsewhere, although this generally depends on the car, make, supplier and so on.

Most OEMs specify a deep cycle absorbent glass mat (AGM) battery for their automatic start-stop systems. They also use advanced power/battery management modules to keep the alternator and battery under control. Because AGM batteries are less temperature sensitive and have a much lower internal resistance compared to standard wet lead-acid batteries, they can charge relatively quickly after the engine is turned on. Ergo, better recovery after a start.

That said, using the wrong battery can ruin things, and without realizing it, people may blame the auto start-stop system instead. However, start-stop is not without possible errors. Your engine mounts may be subject to increased wear and tear due to repeated starts and stops, or the battery itself may fail due to a voltage mismatch, all of which can lead to increased maintenance over time. Although AGM batteries can last longer, they are quite sensitive to overcharging.

You may be concerned about your car’s engine wear, especially in cold conditions when keeping a car engine warm is important, but the on-board computers are smart enough to monitor the oil temperature and act accordingly. If the engine has been switched off for too long (via start-stop) or is about to get cold, it will start again to prevent internal damage. In addition, there are manufacturers such as Federal-Mogul who are developing special polymer-coated bearings for start-stop engines that can withstand up to 300,000 starting cycles or more, which is three times the life of a normal main bearing.

Long story short: don’t worry too much about automatic starting and stopping; it can actually be great. Like it or not, technology is here to stay. However, if you want to retrofit the system (for whatever reason), this may not necessarily be an easy adjustment or even a good idea.