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Would Auto Start/Stop Reduce Starter Life?


My 2013 BMW 328i has a fuel-saving feature (as perhaps many other new cars): As soon as you stop at a stop sign or red light, the engine turns itself off automatically, and once you release the brake pedal, it starts again. In a traffic or city driving where you may stop, say, 30 times, the starter works on average 30 times more than a regular car. Of course, the fuel economy may become significant; the car stops running idle for a total of 20+ minutes in each commute. I am concerned that the savings in fuel (and emission) would cost lower life of the starter than a car without this feature. What do you think of this feature?

It’s not the same starter. It’s a completely different set up. In some cars, like the Prius which has been around a long time it does this as well. There have been no issues that we are aware of in premature starter failure. Nor, are there issues with golf carts and many other vehicles where this is designed in. After all, the starter motor is just an electric motor, and in some units, not yours perhaps, stays engaged all of the time where the biggest wear occurs, either by belt or gear and acts as an alternator when the car starts. It may be the most reliable part of newer cars with this feature. In some other cars like mild hybrids, it assists the gas motor once started and helps provide propulsion. These things are perfectly capable of outlasting…the car and perhaps the driver.

Certainly the starter works harder and more often, but it should be designed to handle the work. I’d expect it to last, but time will tell.

This isn’t like a Prius. I think it’s a regular starter system beefed up to handle the load. It should handle it but it’s new, so who knows. I’ve read the BMW system isn’t the smoothest. I’d probably turn it off.

It isn’t like this isn’t a proven technology. If a golf cart starter can last as long as it does ( many years) with restarts that far exceed many cars…it ain’t rocket science. Not to say they would operate the same, but the ONLY reason it would be prone to failure during the life of the car is if we’re designed to. It’s neither a huge expense or a daunting engineering task. And, I will bet, not only isn’t it the same starter, the least of your worries, but it doesn’t engage in exactly the same way, the biggest of your worries. My reference to the Prius is only with respect that restarting in cars has been around for a while. If you can’t take existing technology that works, tear it appart and copy it, you can’t work in China…or anywhere else.

I think it’s just another useless feature on a vehicle like tire pressure monitoring systems. The thing that I would be concerned about is properly warming up the engine during short commutes. That can affect the life of the engine. I hope BMW has some way of keeping the system deactivated until the engine reaches proper operating temperature. If it doesn’t then starter and battery life will be the least of your worries.

Yepp, BMW system is same as Prius. There, I saw it on the Internet. Must be true.

Europe has had this setup for a long while now, it’s just starting to come over to the states to help with CAFE

It would drive me nuts especially when its 10 below zero and trying to stay warm in traffic. I would be disconnecting it. Pay $60,000 and it won’t stay running at a stop light?

Missileman, I’m admittedly not familiar with these systems, but i’d bet that engine temperature is a factor in whether the engine is shut down when stopping. The cat converter would have to be kept hot to do its job well, the engine would have to remain hot to maintain efficiency, and with all the effort that goes in to ensuring that these things I doubt if temperature would be ignored as a variable in the ECU programming.

I’m just guessing. But I’d bet breakfast that temp is considered.

I consider that there is an average number of events without breakdown for any component. Under that supposition if it is the same starter motor as used in a regular car I would expect by your stats 1/30 the average life expectancy. Hopefully they built a better starter motor. So the next step would be to estimate fuel cost savings vs starter motor replacement expense, all things being equal.

Well, I don’t know how or why the starter in question would last as long or longer than a standard starter on a standard car, but if it is true, why don’t they make one that good for the average car?
I know I would not be interested in a car that died at a stop light and started up when you let off the brake.

Money. It costs more to make a starter that lasts the number of cycles necessary for a start/stop system than it does to make a starter that’ll last the number of cycles necessary for a conventional engine system. Personally, I’d rather have what I have for the price I paid than have everything designed to last forever and not be able to afford a car.