New cars that shut off at stop lights and stop signs?

Post by **theWIFES_S70** » 27 Aug 2017, 18:40

Dropped my son off at college the other day and had to rent a car for the trip. (My wife wanted her car for the weekend...) So I get a 2017 Impala. Not a bad car if you like American cars, roomy, somewhat comfy, great 40-80 pickup for getting off and on the I80... But, the "fuel-saving" feature that shuts the car off at stop signs and turns the car on when you let go of the brake pedal...

These dealers are going to make a killing replacing starters every three years.

Any insight on this feature? Does it really save that much gas? A hundred-mile trip around here on Thanksgiving will amount to 10 years of starter wear in a day! I don't know about this feather.

https://www.autotrader.com/car-news/che ... ogy-227939

Post by **jimmy57** » 27 Aug 2017, 19:55

The starter is beefed up and so is flywheel. Volvo has had this on some 5 cylinders in EU for several years. All of the new 4 cylinders have it. I have been repairing cars for 40 + years and cars that die when you stop have been a big part of repairs. I took time getting used to it. Volvo's start-stop is among the least noticeable and I no longer pay much attention. It does save fuel for persons that do much stop n go driving. I am not sure if GM or others do this but Volvo uses a second small battery (actually a motorcycle battery as why re-invent the wheel?) to keep everything on for that moment when starter is engaged and needs full main battery current. By not shutting off accessory loads you don't notice the start sequence.

Post by **June** » 27 Aug 2017, 21:13

jimmy57 wrote: ↑27 Aug 2017, 19:55 The starter is beefed up and so is flywheel. Volvo has had this on some 5 cylinders in EU for several years. All of the new 4 cylinders have it. I have been repairing cars for 40 + years and cars that die when you stop have been a big part of repairs. I took time getting used to it. Volvo's start-stop is among the least noticeable and I no longer pay much attention. It does save fuel for persons that do much stop n go driving. I am not sure if GM or others do this but Volvo uses a second small battery (actually a motorcycle battery as why re-invent the wheel?) to keep everything on for that moment when starter is engaged and needs full main battery current. By not shutting off accessory loads you don't notice the start sequence.

A motorcycle battery, Volvo really thought of everything! The drive e is the main reason I have not bought a S90. There is no way to turn the feature off according to my dealership and no easy button on the dash like the 60's. I hate the easy button too. I understand the feature is required in Europe but I live in the USA. Really who wants the annoyance of the engine stopping and starting in a luxury car? I also prefer having a key with a ignition switch and the ability to unlock the car with the key.

The good news is Volvo is going electric. Undoubtedly the S/V 90 will come in full electric version and drive e will not be necessary. Also if Volvo does it right the electric version will drive as good or better than my T6 with as much power. I have driven a Tesla and drive was impressive.

June

Post by **mrbrian200** » 27 Aug 2017, 21:38

Does the Volvo start/stop system utilize a reversible alternator? Valeo I-StARS would be system most likely for Volvo to utilize.
If Volvo does use this type of system I would expect it to be pretty unobtrusive. I've seen and heard some start/stop enabled GMs which use the starter on the flywheel: It would probably get somewhat annoying after awhile in stop and go/inner city driving.

Post by **theWIFES_S70** » 28 Aug 2017, 20:39

Wow, I didn't know that Volvo was doing this already. The Chevy stop-start system is really clunky. It really "lets" you know you're experiencing a weird (annoying) emissions thing. Glad to know Volvo is doing it better than most!

Post by **jimmy57** » 08 Apr 2018, 16:15

The setting on Center Stack Display on XC90 is on S90, V90, XC60, and the XC40. All Volvos with S/S have the defeat feature.
The engine mounting helps with making it less noticeable and the engine starts with brake pedal lift to give the head start to make a delay reduced or eliminated.
The Valeo system is for Supplemental Propulsion plus battery charge plus regenerative SP battery charge. That is not what Volvo is using now. The alternator will be bigger and have capability of being a 3 phase electric motor. Fuel the engine less and drive the engine with that alternator-motor to lessen fuel use to get up to speed. Also can be used as additional torque and horsepower with full throttle briefly. When you coast and injectors are shut off the A-M charges the 48 V SP battery for free as a drag and reduces brake pad use. 48V charge rate, and thus drag level, is brake pedal apply level dependent. The A-M is 12V battery charge and power source (alternator) as normal the rest of the time. This is the story about this for now. Some details may be tweaked a bit before it shows up on Volvos.

The BMW I8 uses a system like described but not so much as an MPG thing but as supplemental power to the 3 cylinder turbo engine for performance according to what I've read in tech literature. The other tidbit that I hadn't thought of is the extra things done to the belt drive for alternator-motor. Bigger belt due to higher load but also a dual side floating tensioner. The drive of alternator puts stress on one side and as a drive motor stress is on the other side.

93Regina · Post by **93Regina** » 08 Apr 2018, 21:06

jimmy57 wrote: ↑27 Aug 2017, 19:55 I am not sure if GM or others do this but Volvo uses a second small battery

Buick Enclave use to store battery in rear cargo area, but now with engine stop-n-go, its back in engine compartment, and its a full sized battery.

Most drivers will not notice engine off/on sequencing....it can be over-ridden in several ways...if AC is not keeping up, engine will stay on....there is no over-ride switch, last I knew.

Post by **mrbrian200** » 09 Apr 2018, 00:00

Thanks for clarification as to how the Valeo system is designed/implemented. The write up I saw on it was written somewhat like a press release and gave me the impression it might be suitable for use in conventional ICE start/stop systems. But without the noise and delay associated with starters on the flywheel.

You touched on engine braking. As far as MPG is concerned, I do not necessarily consider fewer cylinders/smaller displacement my friend. Depends on the terrain and driving style. Around here (Great lakes basin, 'not quite flat' rolling terrain) I really notice the difference in engine braking while traversing modest downhill grades between the S60 I5 and two previous comparable size sedans with V6s that were geared a little higher. I practice moderate hypermiling techniques when traffic conditions permit, which around here is about half the time. Previous V6 cars would coast/fuel cut in places where I can't quite take my foot off the pedal in the S60 or it'll slow unless I put it in neutral. I know that's not a good idea with an AT, I don't make a practice of it. Both of those previous cars virtually matched the econ I get with the S60 (low-mid 20s city, approaching 40 on the highway when conditions are right) despite having larger engines with more internal moving mass. But they were geared a little higher=less engine braking. Therefore they would coast with no added fuel more often. Also in play: despite having more reciprocating mass that's associated with more cylinders, when the trans is geared higher the lower rotational speed cancels out some of the 'negative impacts' of a larger engine as opposed to a smaller engine with a 'lighter' internal reciprocating mass but is revving faster. Remember Mass*Speed=energy.

The worst was my sister's old Jetta (MY02 2.0L I4 NA). That thing was kind of sucky in the econ department any time I drove it considering the small size of the Jetta. Frankly the FWD S60 does as good, maybe even a little better, without putting up with a boxed in/cramped interior of a compact. I'm 6'2".

Post by **abscate** » 09 May 2019, 09:19

My poor bride drove a diesel miniBus all over Italy with a standard and wondered why she get kept stalling it at lights. Unflappable as women are, she just pushed through and restarted it each time, about mid trip she mentioned it on a call home and I figured it out.

Post by **matthew1** » 09 May 2019, 09:30

theWIFES_S70 wrote: ↑28 Aug 2017, 20:39 It really "lets" you know you're experiencing a weird (annoying) emissions thing.

Hey if you're going to the trouble of building in a new component, might as well let drivers know it's there.

abscate wrote: ↑09 May 2019, 09:19 My poor bride drove a diesel miniBus all over Italy with a standard and wondered why she get kept stalling it at lights. Unflappable as women are, she just pushed through and restarted it each time, about mid trip she mentioned it on a call home and I figured it out.

Manual transmission stop/start?