Do stop/start systems wear out the starter motor? Discussion with an engineer.

[MetroMPG]

Flickr image: Doug McCaughan

Green Car Reports has an interesting article today about engine stop/start systems. It addresses one of the most common objections many gearheads have against the fuel saving technology: that it must wear out the starter motor.

The piece is an interview with an engineer at an OEM parts supplier, who explains how the starters in stop/start cars are designed differently than conventional starters.

Major differences:

• Lower gear ratio/higher torque starter motor reduces brush wear
• Stouter brush material composition
• Bearings instead of bushings
• Solenoid separates pinion engagement from starter motor contactor functions for greater control
• Communication with ECM to control fuel/spark in the individual cylinder which is closest to being able to fire up the engine

Deeper explanation & discussion in GCR's story:
Don't start-stop systems wear out your car's starter?

Now if only they would interview an engineer to explain why stop/start systems don't cause additional engine wear from oil drain-down.

[t vago]

My takeaway is that vehicles that have dedicated start/stop systems also have starters engineered to do start/stop. Traditional cars without start/stop will likely see increased starter wear if start/stop is implemented.

[MetroMPG]

Makes sense. Ask me in 20 years how my now 20 year-old conventional starter has held up, being used much of its life like a "stop/start" starter.

Side note: a new-looking Mercedes sedan startled me slightly the other day as I was biking past and its starter motor engaged as it pulled out from a side street stop sign.

[t vago]

Yes, there are also the questions of exactly how extra wear would one expect from a traditional starter in a start-stop role, and if it would be possible to retrofit some of the newer features on the traditional starter (like the needle bearings or better brush material).

[Hersbird]

He basically admits it does wear the starter and why wouldn't it? The question is do ALL the systems use a better built starter? Does that also mean it lasts just as long but costs 2 or 3 times more? Do they also think to make it easy to change?

[jamesqf]

Not all start-stop systems even use the starter motor.

[jakobnev]

Now if only they would interview an engineer to explain why stop/start systems don't cause additional engine wear from oil drain-down.

Maybe it does, but a modern engine still outlasts the rest of the car. (Just maybe)

[LittleBlackDuck]

Originally Posted by MetroMPG

Now if only they would interview an engineer to explain why stop/start systems don't cause additional engine wear from oil drain-down.

How long do you let your car sit before draining the oil? Seriously, if a minute or two of sitting with the engine off causes wear issues from oil drain back then the engine must be nearly at the point of self destruction or very badly neglected.

The article you quotes states that the off time is generally 45-90 seconds.

[MetroMPG]

Yeah, I was playing devil's advocate with the oil drain down question because it's another objection that comes up a lot in comments about stop/start systems, especially from traditional "enthusiast" sites.

You only have to look at fleet use of hybrids (eg. high miles taxis in urban service) for evidence that it's not a problem.

[oldtamiyaphile]

IIRC Renault claim 200,000+ cycles from their stop starter (that would be once a mile for 200K miles). Stop starter on my 2 cylinder is about the size you'd find on a V8. I'd be very surprised if anyone ever wore one out.

For non S/S cars, you can investigate using the (larger) starter from a diesel model, just swap over the pinion/ clutch mech. I did this on an older Mercedes.