Is Auto Stop/Start Healthy?

[Yabi]

So I was driving in NYC the other day and my car must have auto stop/started twenty times in less than five minutes and it got me thinking, can it really be healthy for the engine to turn on and off that many times in such a short amount of time? I thought about turning it off but isn’t that exactly the use case for auto s/s? Curious if folks smarter than me can chime in.

Ps, NYC traffic is madness!

[guglielmo]

Just turn it off. The starter might go one day, but probably long after you sell the car.

[dbuxton13]

Short answer: Not unhealthy.

Long answer, if you really really want to know the engineering behind it:

Automotive engineers don't use 'traditional' starter motors in these situations. The starter used for start-stop systems combines several technologies, designed for multiple, long-term use.

(1) The gear ratio from the starter-drive pinion to the flywheel ring gear is optimized to make the starter's motor turn more slowly. This can be done without materially changing the design of the transmission or flywheel at all on existing designs.

(2) The composition of the carbon and copper brushes on a start-stop motor differs from its traditional counterparts to increase longevity without accelerating the wear on the commutator.

(3) Rather than rely on oil-impregnated bushings for the rotating assemblies, start-stop starters mostly use needle bearings.

(4) The solenoid on start-stop starters decouples the mechanical action of engaging the drive pinion into the flywheel from the electrical action of stopping and starting the motor. This allows for a dedicated design to turn power on and off to the motor, optimizing contact design and wear, against contacts that have to be integrated as part of a spring-loaded plunger. This also reduces the electrical load requires to turn the engine, so that there is enough current available for accessories/lighting to operate during the start event.

(5) Finally, start-stop motors are integrated with other technologies that identify when each cylinder of the engine will reach top-dead center. That lets the fuel injectors pulse and fire during the middle of a complete rotation of the crank, against having to wait for a complete revolution that lets the first cylinder reach that position to start the fuel-spark timing sequence.

Source: https://www.greencarreports.com/news...r-cars-starter

[Yabi]

Short answer: Not unhealthy.

Long answer, if you really really want to know the engineering behind it:

Automotive engineers don't use 'traditional' starter motors in these situations. The starter used for start-stop systems combines several technologies, designed for multiple, long-term use.

(1) The gear ratio from the starter-drive pinion to the flywheel ring gear is optimized to make the starter's motor turn more slowly. This can be done without materially changing the design of the transmission or flywheel at all on existing designs.

(2) The composition of the carbon and copper brushes on a start-stop motor differs from its traditional counterparts to increase longevity without accelerating the wear on the commutator.

(3) Rather than rely on oil-impregnated bushings for the rotating assemblies, start-stop starters mostly use needle bearings.

(4) The solenoid on start-stop starters decouples the mechanical action of engaging the drive pinion into the flywheel from the electrical action of stopping and starting the motor. This allows for a dedicated design to turn power on and off to the motor, optimizing contact design and wear, against contacts that have to be integrated as part of a spring-loaded plunger. This also reduces the electrical load requires to turn the engine, so that there is enough current available for accessories/lighting to operate during the start event.

(5) Finally, start-stop motors are integrated with other technologies that identify when each cylinder of the engine will reach top-dead center. That lets the fuel injectors pulse and fire during the middle of a complete rotation of the crank, against having to wait for a complete revolution that lets the first cylinder reach that position to start the fuel-spark timing sequence.

Source: https://www.greencarreports.com/news...r-cars-starter

Great write up, thanks!!!

[Nez136]

I also read somewhere that the starters are good for something like 20,000 starts.


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[Yabi]

Thanks everyone! I appreciate the feedback!!