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Listen carefully next time you hear a car idling, it’s a sound that you may not hear much anymore. And that’s a good thing. More and more automakers are using engine stop-start systems to boost fuel efficiency. The system, which shuts down a vehicle’s engine at idle and immediately restarts it when the driver presses the accelerator is becoming a popular technology.  It is a feature of all hybrid cars on the market now and now we are starting to see them on conventionally powered cars.

They save fuel

Stop-start systems can cut combined city-highway fuel consumption by 3-10 percent, and even more when they’re combined with hybrid drive systems. By eliminating engine idling, stop-start systems also reduce toxic and smog-causing tailpipe emissions. They are especially effective in city driving situations where a lot of stop and go driving occurs.

How they work

The brains behind engine stop-start systems is the main CPU that controls the car. Stop-start systems are designed so that depressing the brake pedal sends a “ready” signal to the engine controller. When the car comes to a complete stop, the controller shuts the engine down and pre-positions the starter motor, transmission and fuel injection system to provide a rapid engine restart. This occurs when the driver either depresses the accelerator pedal or releases the brake pedal. According to Newark Automotive of Newark, DE, a Chrysler, Dodge, Jeep, Ram dealer, most systems aim for the restart to occur in half a second or less.

What else stops

If you turn off the engine in your car or truck, the air-conditioning stops working too. That’s because most A/C systems use power from the engine to run their compressors. Losing your cabin AC isn’t a huge problem on mild days, or when the stop period is short, but it could be on very hot days.  What the auto manufacturers have done to address this is to put in circuitry that simply boots the engine back on if the cabin temperature rises too high.

A battery drain

Stop-start systems aren’t hard on engines, but they do demand a lot of the vehicle batteries. While a conventional car or truck might call for high amperage for the starter-motor three or four times a day, a vehicle equipped with a stop-start system might cycle that drain on the battery several dozen times a day.  This is harder on the battery and automobile manufacturers generally put larger batteries in cars that have stop-start systems.

Stop-start downsides

Are there downsides to having a Stop-start system? Well, many drivers find it disconcerting when the engine shuts off each time they come to a stop so there is some “getting used to it” involved. Finally, if the special 12-volt batteries needed for stand-alone stop-start systems do need replacement, they are about twice as expensive as conventional 12-volt lead-acid batteries.

Nothing New for Hybrids

Stop-start systems are old hat for people who drive hybrids. These cars always have incorporated stop-start for years to help improve fuel economy. Unlike stand-alone stop-start systems, which rely on 12-volt batteries to help keep costs down, hybrids are able to draw on their electric-drive systems’ robust but expensive nickel-metal and lithium-ion batteries.

Rapid Growth Predicted

Because of their simplicity and effectiveness, stand-alone stop-start systems may become ubiquitous on new cars and trucks in the U.S. in coming years.  The technology works and owners seem to be fine with them.

Earthgarage. Greener Car. Fatter Wallet.