Stop start batteries... is it a sign?

It's likely to be one of the first things the car switches off if the battery is low.

Get a multimeter and see if the voltage has dropped a bit.

Mine does that, it apparently shows that the battery is getting older, and not holding a full charge. During colder weather the battery will get a hammering anyway.

Mine started working yesterday after a few miles drive, but normally I’m not driving more than about 15 miles with it being dark at each end.

I have got a little digital battery check jobby, that goes into the aux socket, needed one for checking the battery state on stored cars at work, I must remember to put it in the car and run a check on the static charge status, the car will need a service in another 6000 miles by which time the battery will be four years old, and may well need replacing.

Yes.

New battery may want programming in. Had similar with our Focus before the battery went. It worked again for a while and then didn't. I didn't have it reprogrammed as I didn't realise for several months that might be what the problem was and given that car's use as a short journey / runabout it's probably better for it and the battery that it doesn't work.

Yeah, I'm being lazy, i'll do the multimeter (battery under the boot panel is annoying for this). Car is coming up to 5 years old so it's probably about time.

Minimum temperature we've had in the last few weeks is about 19, so definitely not cold weather.

Like the idea of a battery check jobby.

Could also be a module needing reset, my Focus was all flaky until we got that done and it's been fine since.

Dunno what software and dongle an Alfa uses but it might be relatively cheap to pick up a suitable dongle and software to check what error messages are stored and what the battery health is like.

Do check if you have more than one battery.

My V70 had a beautifully hidden stop start mini sized AGM battery under the scuttle.

Dunno what software and dongle an Alfa uses but it might be relatively cheap to pick up a suitable dongle and software to check what error messages are stored and what the battery health is like.

I looked into that recently. IIRC it wasn't as cheap as you'd hope. Luckily I have a mate that runs a European car tuning business. I recently had to get a windscreen replacement and the firm didn't have ability to clear an erroneous fault code on the screen camera and therefore weren't able to replace the screen until I got it done. Massive PITA to go to an Alfa dealer for me, but my mate was able to do it.

Definitely only one battery.

I looked into that recently. IIRC it wasn’t as cheap as you’d hope.

Ah well, it usually sits on either end of two extremes. Was worth checking though.

I'd speak to your mate and see what diagnostics come back with, at least you might be able to reset the battery control module and let it relearn if there aren't any troubling fault codes.

Depends upon your car usage like others have said above. My mum's Nissan Note is used once a week if it's lucky and it can take a solid 30 minutes of running before the stop/start begins to work again at times despite the battery being less than a year old and coded correctly. The original battery lasted 6 years before it just packed up without any obvious warning.

Does it get taken out for long drives? It might just be needing a few good runs to get the battery charged up and ready to go.
Happens with my car as it does short journeys but a decent run seems to fix it for a few days.

It rarely gets used for less than 30 mins on the open road 50-70mph - should be enough i'd have thought.

Is this a typical sign that the batteries on its way out?

Our car battery is 11 years old and the stop start hasn't worked for at least 5 years. No issue with normal battery function.  Van is 6 and that's the same despite a 30 mile commute to charge it every day.

I definitely won't be changing them just for the stop start to work again.

Just bought a car and stop start doesnt work. Fully charged the battery and still doesn't work.

Either it's broken, not holding enough charge or the battery isn't correct somehow.

Its not a problem until you hit traffic snd watch your mpg drop and your the only one with fumes coming out the exhaust.

This happened to me on a fairly new car I bought 2nd hand. The car had been sat for sometime without the battery being trickle charged.

New battery and stop / start worked fine again

Standard car batteries cannot be recovered once the charge has got too low

As Matt mentioned, they often have a separate smaller battery, I know my Discovery has (currently not working)

Is this a typical sign that the batteries on its way out? Incidentally, I find it odd that there’s endless tech on modern cars, but nothing telling me what my battery health is.

If I flick through the display options on my (aftermarket) stereo - ie whether it shows the station, the track curently playing or whatever, one of the surprise  options is it displays the battery voltage.

Batteries take a long time to charge. The big stop-start battery in my Volvo would take 4+ hours of motorway driving to refill after standing for a long time.

Sharing my own experience. 2021 E Class Mercedes. Just had its 46v battery replaced after 18,000 miles. Would have cost me over £3,000 but covered under warranty.

I would drive to work (60 miles) and would get a message saying that the 12v battery needed charging. Then we drive to the Alps (11 hours non-stop) and even that wasn’t enough!

Turns out it was the 46v battery not feeding the 12v battery. Apparently they don’t like to be left alone and don’t actually charge well unless you drive for hours and hours.

Sounds like a design flaw to me, but let’s see what happens next. The dealer said that Mercedes have refused these warranty claims on slightly older cars because during Covid when cars sat idle for long periods they had lots of failures. Sounds lame to me, but might be indicative of lots of cars now having battery issues. The damage caused by battery drain and inactivity over the last 3 years has stored up lots of battery issues. ‘There’s a lot of it about!’

I've just had a thought @reeksy as it's an Alfa, do you get a warning light on the dashboard after a short, (5 mins?) time.

My daughter has a Fiat 500 which also doesn't do stop start, (that's 3 of 3 in our house!) but this one is because an actuator arm that depresses the clutch position switch has broken off. It's held on by a couple of pigeon shit spot welds and is a common problem apparently. Some Alfa's may be similar from the same company stable.

FunkyDunc
Free Member

This happened to me on a fairly new car I bought 2nd hand. The car had been sat for sometime without the battery being trickle charged.

New battery and stop / start worked fine again

Standard car batteries cannot be recovered once the charge has got too low

Sometimes you can get them going with a smart charger. With the price of stop/start batteries, it's worth getting a cheap one like the Maypole MP7428 I have. It was able to recover my car's battery which died after being laid up for covid. I seem to recall it detected the fault and went through some kind of recovery cycle.

Turns out it was the 46v battery not feeding the 12v battery. Apparently they don’t like to be left alone and don’t actually charge well unless you drive for hours and hours.

There are a few manufacturers who've had this issue with the 12v charging side of the 48v electrics. Some have rolled out software updates to fix. Others haven't (or their hardware doesn't have the capability to take a better software).

My V70 had a beautifully hidden stop start mini sized AGM battery under the scuttle.

I had the original version of that in my C30 DrivE a decade or so ago. The list of "special considerations" to protect the battery was HUGE. And they were about £600 to replace and recode to the car. By the time i got my second and third version of the system, they could (almost) be hot swapped. For about 100 quid.

@damascus

Either it’s broken, not holding enough charge or the battery isn’t correct somehow.

Or you need a software update, a module reset or something else that's seemingly unrelated. I thought my alternator was on the blink as all signs pointed to that, nope, was a software issue and an update sorted it.

In my case it was the first signs of battery failure. Stop start unavailable initially, followed by slower to turn over, followed by not catching on the first turn in very cold weather then it's time for jump leads. Can't complain really, it was the original battery and the van will be ten years old this year.

I always turn it off. Stopping and starting an engine constantly must be a sure way to premature wear.

I always turn it off. Stopping and starting an engine constantly must be a sure way to premature wear.

I also don't bother clipping my seatbelt in, as I don't want to wear it the mechanism.

I also don’t bother clipping my seatbelt in

Don't be silly.

No sillier than thinking that they don't actually design in margin for more stops and starts... and protections to make sure it doesn't stop when it would cause wear.

Same has just happened to a mate. Got new car, older car not used for a couple of months till he got round to selling it, stop start light now on. We've told him to drive it for a bit, if no change, new battery.

Stopping and starting an engine constantly must be a sure way to premature wear.

You should write into a car manufacturer - they need to know!

There are loads of safeguards that won't do it unless the conditions are such that it won't prematurely wear the engine so I don't think its that big of a deal. There will always be some stories you hear but of course, no-one posts on the internet that their car's fine.

Start stop stopped working on my car last winter unless it'd been driving for ages then it would do one or two starts and turn off again (it shows you if the system's active on the dash). So I had the battery tested and it was giving 400A instead of 800. That was enough to start the car normally but the system didn't like it so shut the start/stop off. New battery, all fine. If I don't drive it for a couple of weeks in cold weather it takes some time to refill the battery.

On the other hand our hired Kia rarely did start/stop, and that was almost new.

No sillier than thinking that they don’t actually design in margin for more stops and starts

Maybe they do, maybe they don't. So long as it lasts 3 years/100k or whatever their responsibility is, maybe that's 'their' target. I do know that generally lots of very expensive parts now need changing as routine service items eg DPF's, DMF's etc and engines are susceptible to a lot of wear and produce more horrible stuff at start up.

It's another way of frigging the data to pretend the emmisions are lower and fuel economy is higher whilst introducing more wear (additional batteries required and therefore replaced etc) and unreliability.

Conflating a safety system that has saved countless lives with a costly workaround that actually reduces reliabilty is a bit daft IME. Your cars, do what you like but I'm not joining in on this one.

 I do know that generally lots of very expensive parts now need changing as routine service items eg DPF’s, DMF’s etc

Do they? My 11 year old diesel hasn't had anything replaced yet.

engines are susceptible to a lot of wear and produce more horrible stuff at start up.

I think that's only when they're cold.  Are you saying that leaving your car running produces less horrible stuff?

additional batteries required and therefore replaced etc

Our three cars only have the one battery each

Conflating a safety system that has saved countless lives with a costly workaround that actually reduces reliabilty is a bit daft IME

Are you sure you meant to use 'conflating'? Because that doesn't make sense.

Maybe they do, maybe they don’t. So long as it lasts 3 years/100k or whatever their responsibility is, maybe that’s ‘their’ target.

Targets haven't changed in the 25 years i've been doing this. Cost of maintenance has changed (more emissions controls etc), but the time to massive and terminal failure is (broadly) the same, some may "fail" earlier due to being uneconomic to repair though.

I do know that lots of very expensive parts now need changing as service items eg DPF’s, DMF’s etc and engines are susceptible to a lot of wear and produce more horrible stuff at start up.

Soooo, you really don't know then, it's *cold* start that does the majority of the nasties, a minimal load, hot start barely even registers. Stop/start systems inhibit stops with a cold engine, they've been doing that since it was first introduced. DPF/DMF aren't service items either. Never have been, neither are catalytic convertors or NOx traps.

It’s another way of frigging the data to pretend the emmisions are lower and fuel economy is higher whilst introducing more wear (additional batteries required and therefore replaced etc) and unreliability.

FWIW, stop start is one of the best systems in a conventional driveline for reductions in emissions and increases in fuel economy for such a small added cost. Not sure if that many conventional stop start systems still uses an auxiliary battery anymore, i know most of the big players dropped them years ago. They weren't needed.

My car has a big battery for the start-stop and a small auxiliary battery which powers the alarm and remote locking etc. This is a good way to do it, IMO, because if your battery goes flat you only need to boost it enough to switch on the electronics, and the main starter battery (the expensive one) is protected. I don't think this is related to it being start/stop though.

The biggest downside IMO is that when the battery eventually needs replacing it's £250 not £120. That said, mine lasted 9 years so it's not a big cost in the grand scheme of things. And I'm happy that it's not chugging out pollutants when I'm stopped.

I would rather have one of the mild hybrids though so it spends more time stopped and can creep forward in traffic. Wait, no, actually I'd rather have an EV and get rid of all that ICE related bollocks.

This is a good way to do it, IMO, because if your battery goes flat you only need to boost it enough to switch on the electronics, and the main starter battery (the expensive one) is protected.

Interesting, is this the Merc?

I don't really understand though.... why/how is your main battery protected?

And "you only need to boost it enough to switch on the electronics" ..... for what?

(obvs you've got two batteries to go wrong instead of one!)

Edit: Wait.... do you mean if there's a power drain from the alarm/central locking system?  If so, gotcha - although there's also a number of systems connected to the main battery that could just as easily drain it.

Interesting, is this the Merc?

Yes.

The small one in the boot is to power the alarm and central locking and whatever else is needed when the car's off. The main battery is disconnected, at least I think so.

Car starter batteries are designed for maximum current delivery not maximum capacity. So the aux battery, whilst smaller, has good capacity. I've never run it flat, but if I did I assume I'd still be able to open the car manually and start it with the key which would (you'd hope) use the main battery which has been protected from being flattened by the alarm.

It's 9.5 years old and the aux battery still tested ok. It's in the boot under the floor, so it's an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

The Prius had a similar aux battery that you could flatten by leaving interior lights on, but since the main traction battery was 300V you couldn't boot up the electronics with that alone. You had to boost the aux battery using jump leads but as soon as you got everything booted up it would run from the 12V supply from the inverter/transformer off the traction battery.

My battery failed about 2 years after stop start stopped working, so mark it in diary.

They always fail when critical, day before airport run.

Nice to get a warning.

I’ve just replaced the AGM battery in my CLS. The stop start was intermittent at the best of times but it’s been difficult to start at all recently and a smart charger indicated the battery was at 60%. By using said smart charger on maintenance mode I haven’t needed to get the new battery coded and the start stop is fully operational.
I got the battery from ECP’s eBay shop for under £140 delivered.

I just swapped the battery as normal on the assumption that the aux battery would keep everything running whilst the main one was disconnected.

I thought that too but was assured I needed to use the charger. 🤷‍♂️

Seemed to work ok. I had heard that you on some cars you need to tell the car what battery it is so it can change charging or whatever accordingly, but I didn't do that. I seem to remember paying slightly more for a battery that was identical in spec so it wouldn't matter.

It’s in the boot under the floor, so it’s an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

So it seems that you can..... the battery for my car is under the passenger seat and is lead acid!

It’s in the boot under the floor, so it’s an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

So it seems that you can….. the battery for my car is under the passenger seat and is lead acid!

Indeed - see a transit with a lead acid directly under the drivers seat and the contacts for battery less than 2cm from the steel mechanism....

Seemed to work ok. I had heard that you on some cars you need to tell the car what battery it is so it can change charging or whatever accordingly, but I didn’t do that. I seem to remember paying slightly more for a battery that was identical in spec so it wouldn’t matter.

It's not the spec of the battery that matters, it's the aging factors. As they get older they need more energy to charge and the discharge curve changes. So all your electronics (and alternator/generator outputs may need to be tweaked).
Depends how shagged the battery was when you took it out.

Cars with 48 volt (and higher) system don't care, because the battery systems are doing all sorts of internal measuring and reporting out anyway. And they can monitor the 12v battery status much easier, as there's no alternator wanging random current spikes all over the place.

Didnt read all the replies. Ignore

It’s not the spec of the battery that matters, it’s the aging factors. As they get older they need more energy to charge and the discharge curve changes. So all your electronics (and alternator/generator outputs may need to be tweaked).

So the car just needs to be told that it's been replaced? There are various part numbers and coding for those parts in VW, not sure how much it matters.

Depends how shagged the battery was when you took it out.

Not really shagged. It still started perfectly well, just the start-stop didn't work much.

So the car just needs to be told that it’s been replaced?

I bought a used Fiesta for my daughters and it came with a new battery - but the stop/start didn't work.  A bit of googling showed that there was a short series of actions* that told the car the battery had been replaced.  Worked as expected after that.

*

Ign on for 10 secs
Press fog lamp switch 5 times
Press hazard switch 3 times
Wait up to 10 secs while watching battery light
Battery light flashes
Ign off.

So the car just needs to be told that it’s been replaced?

Essentially, yes. The car knows the spec of the battery, and the curves etc when it's a new battery. Then adjusts as the battery degrades.

There are various part numbers and coding for those parts in VW, not sure how much it matters.

How many wires did you connect to the battery, more than two. i.e. Does the battery have it's own ECU?
If not, coding and part numbers means nothing.

Quick work of warning on this subject. My 80 Y/O dad had Halfords replace the battery on his stop/start Ford Kuga and it never did seem right and hardly ever start/stopped anymore. less than 2 years later he’s had a load of random electrical problems that have been traced to a duff battery.

The battery had a five year warranty but Halfords flatly refused to look at it as apparently “you have to remove them every once in a while to charge properly”. Which is clearly horseshit as the car sees weakly use. I have escalated it on his behalf but hit a brick wall from their customer ‘service’ as a result of this Halfords have made sure they’ll be getting no more of my money as I think it’s pretty poor form.

How many wires did you connect to the battery, more than two. i.e. Does the battery have it’s own ECU?

I think there's a few all bundled into the same connector. I'll have to do some more reading.

https://www.bannerbatterien.com/en-gb/Battery-knowledge/7-HOW-TO-Correctly-registering-start-stop-batteries

@reeksy I take it its a Giorgio platform car of some sort. They are so notorious for it. Practically the only thing that ever goes wrong with them. My Giulia ate its factory battery at 18 months. I half-joke that the mafia knicked half the lead from the factory during production.

The IBS that monitors the battery health under the boot floor may need a software update, but 90% of the time its the batt itself that has gone. Other symptoms will be the heated rear window will refuse to demist.

The only thing you can do is replace it. Then you need to bung it on charge overnight connecting via the IBS negative terminal in the boot (the post that the arrow below goes over, not points at).

[img] [/img]

Thanks @hot_fiat - it's a diesel Stelvio. Never have a need to use the demist in Queensland (or and of the heated seats, wheel etc), but i'll check it all out.

The only thing you can do is replace it.

You mean the battery?

Why do i need to do an overnight charge on a new battery?

I have a 2013 1.6 diesel Doblo with stop start. I got the car at 2 years old. Stop start never worked reliably, and when it did kick in I would shi*e myself thatthe car had broken down.

The battery looked fine on every test I could reasonably do, but replacing it solved the problem entirely and now it works all the time.

Yes replace the battery not the IBS.

The overnight charge through the IBS tells the unit that it’s a freshly charged battery.

Alternatively I think you can do it via the EOBD with MES by setting a flag in the ecu but you’ll need a license. At 5yr old I doubt you’ve a security gateway so it should be pretty straight forward.

You know how to clear the post battery change array of warnings? In a big car park, park up, switch car on, into Drive, go forward a little and go full lock to the left, then full lock to the right, left and right again. Should shut it up.

Also: the quick negative connector that is actually highlighted in the picture - after you’ve changed the battery make sure this is well and truly seated and clicks home. Give it a proper wiggle. I’ve seen a few garages fail to reconnect them with panicky posts from people saying “ooh my Alfa died with loads of errors”, when in reality the poor thing suddenly didn’t have a battery for a few seconds as they drove over a bump.

And all that^ has just reinforced my prejucide that this is a botched solution looking for a problem. No thanks. 🙃

And all that^ has just reinforced my prejucide that this is a botched solution looking for a problem.

What is a botched solution? The battery management stuff is nothing to do with start/stop.

Start/stop works, it saves fuel and reduces pollution. Don't worry about it any more than any of the rest of the million things in your car that can fail.

When you're cycling in town would you rather ride down the side of a queue of cars producing pollutants, or a queue of cars not producing pollutants? If you live near a junction, do you want cars sat outside your house all day idling, or off?

I really like start-stop in the Giulia. It's very seamless and there's loads more going on under the hood with electric circulating pumps for the water, the chargecoolers and most importantly the oil which keeps all the pressures at idle levels or higher and prevents boiling in the turbo bearings on the exhaust side.

Whereas on our old kodaiq or the T6 it seems like a bodge. It triggers too soon (you've often not stopped) and then springs back into life as it realises its mistake. There's an electric water pump, but that only kicks in if you've been giving it the beans, so really you're getting proper engine startup wear all the time.

Blimey, all this complicated shenanigans for a battery. Mixing Alfa's and electronics is always a bad idea. And yes, I had one, a 147 Selespeed when they came out, and it was forever going back to the dealers with electrical issues. Lovely car mind. Had to Microsoft 'reboot' it regular. All the components were Bosch but what ever the Italians did they messed it up.

Some mild hybrids do cut out early, if you are going slowly and lift off - but this is by design. Our hired Kia did this (when it felt up to the task, which was rarely)

There’s an electric water pump, but that only kicks in if you’ve been giving it the beans, so really you’re getting proper engine startup wear all the time.

Why does having an electric water pump make the engine wear?

I'm struggling with electric pump = engine wear.

I changed cars recently. It was not activating the stop/start at point of purchase. To be honest, I hadn't even clocked that it was a feature on the car. Two days later it was doing it every stop consistently. Seems like battery management simply wanted to see more charge in the battery to meet the criteria for enabling the feature.

VW only fit a coolant pump as a sort of half-arsed concession to the fact the engine is randomly off. When it does, the oil pressure drops to 0 and all the journals will start to drain. You'll subsequently get warm start-up wear when it fires up again. That doesn't happen on the alfa as the oil pressure is maintained, piston skirts and bores continue to get sprayed, turbos get fresh oil circulated through them as well as their bodies cooled.

Well weirdly enough this morning the low oil light came on. I topped it up on my way home from work… and now the stop/start is functioning properly for the first time in weeks.

Surely a coincidence, but nice nonetheless.

When it does, the oil pressure drops to 0 and all the journals will start to drain.

Not exactly true - although the oil is not pressurised it's restricted from returning to the sump so there's oil there when the engine restarts.

Whereas on our old kodaiq or the T6 it seems like a bodge. It triggers too soon (you’ve often not stopped)

Stop in drive at Speed, extra emissions savings, it's meant to do that, usually 3kph in a conventional ICE (non-48V) ndue to system safety requirements (related to brake vacuum and steering loads IIRC)

and then springs back into life as it realises its mistake.

You're reducing pressure on the brake pedal (loads of people do it), or the brake pressure calibration isn't very good, that triggers a restart.

There’s an electric water pump, but that only kicks in if you’ve been giving it the beans, so really you’re getting proper engine startup wear all the time.

???
Coolant circulation has no impact on engine startup wear, not with a warm engine. Oil circulation *might* but only if you're standing for several minutes. Most stop start engines i've seen have non-return valves or restrictors in oil galleries to prevent this, or slow it down massively.

@mert You sound like you're intimately involved in this area. Is that right?

Yes, i've been doing this for 20+ years.

K. So, I admit to a lot of (maybe blind) prejudice but I work on the principle of the simpler the better with vehicles.

They've got to a point where repair costs of insanely complex (often non essential) elements are making repairs non cost effective and so writing vehicles off. Very wasteful.

I've also worked on the principle that the less you stress a machine, the longer it lasts. So stopping and starting something 1000's of times more than strictly necessary *must* have consequences beyond the fuel/pollution savings.

Typically what's the fuel saving payback on a 2l diesel vehicle average use profile/average mileage please?

VW only fit a coolant pump as a sort of half-arsed concession to the fact the engine is randomly off.

I think the electric water pump is to circulate hot coolant through the heater matrix to keep the warm air blowing when it's stopped. There could also be an electric AC compressor for the same reason.

They’ve got to a point where repair costs of insanely complex (often non essential) elements are making repairs non cost effective and so writing vehicles off. Very wasteful.

It's not quite like that, I don't think. MOST stuff is the same as it always has been, but there is certainly more of it. Most of it is to do with reducing pollution - so what would you rather?

And really - cars are better than they have ever been. The reason that working cars keep getting scrapped is because people at the other end of the market keep buying new ones. That means there's simply too much supply. People don't want to spend more on a repair than the market value (which I think is absolutely the wrong way to look at it) and this calculation can be affected by the high cost of repairs OR the low cost of a replacement.

Typically what’s the fuel saving payback on a 2l diesel vehicle average use profile/average mileage please?

It's not just about fuel cost, it's about pollution.

So, I admit to a lot of (maybe blind) prejudice but I work on the principle of the simpler the better with vehicles.

It's never simple. A simple petrol engine is going to be noisy, inefficient and/or underpowered, and pollute a lot.

I work on the principle of the simpler the better with vehicles.

Jeepers, you missed that boat decades ago!

I’ve also worked on the principle that the less you stress a machine, the longer it lasts.

I would imagine that simply driving a car is more stressful to a car than a warm start.

Typically what’s the fuel saving payback on a 2l diesel vehicle average use profile/average mileage please?

That will depend on where you drive/how many times you stop!

On an WLTP emissions cycle with active stop start system will save you about ~1.5% fuel economy.
No idea what a "normal user profile" looks like. So i couldn't tell you.
But in heavy traffic city driving, with lots of stop start and such like you might get up to 10% on a short, cross city, journey compared to not having it.
On my drive to work it saves me about 0,0001% of nothing because i have a long drive and virtually no lights or traffic to contend with.

I’ve also worked on the principle that the less you stress a machine, the longer it lasts. So stopping and starting something 1000’s of times more than strictly necessary *must* have consequences beyond the fuel/pollution savings.

Stress usually isn't something you worry about until something is being asked to work outside it's design criteria.
And this duty is designed in. (And typically, in a 12v ICE it'll be around 10-12 times the number of starts, not 1000's. Maybe triple that in a 48v car. Also, starting the engine from a vehicle instructed stop typically takes around 1/10th the load of a key start. There are even some that can start using ignition/fuel injection rather than the starter. I've played with it, and we have built some protos, but it never went to volume as 48V ICE took off, and that doesn't need it. In fact, we reviewed removing the engine speed indication/rev counter for 48v cars, but the engine start (soft start) is so inobtrusive that it's sometimes not possible to tell if it's running or not.)

They also have upgraded of modified ring gears, starters, batteries, fuel pumps, injectors, restrictors or non return valves in oil channels etc etc.
FWIW the total hardware upgrade cost to add stop start to a 12V ICE car in the first place was so low that other than the battery + extra harness ($$) and starter ($), most of the changes we made to the rest of the car we just included in all cars because it was easier than having multiple part numbers

They’ve got to a point where repair costs of insanely complex (often non essential) elements are making repairs non cost effective and so writing vehicles off. Very wasteful.

Much of that is legally mandated emissions equipment, if you're talking powertain/stop/start/engine. If you'd all been driving round with stop start active for the last 15 years, we might not have needed all of it. (i joke, of course we would...)

Would be interesting to hear what you think it "non-essential" though. From a that powertrain perspective.

If you want to try scary stop start, try the latest 48v cars with coast and sail functions.
Lift off the pedal at up to 180kph and the engine disengages itself from the road wheels and then switches itself off until you hit one of half a dozen exit criteria. One of which is stopping... Think the next gen audi's are going 200+

Very wasteful.

Everything about consumer goods is wasteful in one way or another.

Everyone's trying to do something about it (as it's profitable to be less wasteful) but the first one to blink and actually do something concrete about it will probably be the first to go bankrupt.

There are a few initiatives around recycling and reuse, but nothing (yet) properly joined up, except for (sort of) recycling and reuse of EV batteries. Which will take a while yet.

Lift off the pedal at up to 180kph and the engine disengages itself from the road wheels and then switches itself off until you hit one of half a dozen exit criteria.

That's all very interesting info @mert - love it!

I know some cars drop their rpm to idle levels when coasting - how does that work?

it’s about pollution

Time to burn the Witch - I don't care about this. Or rather, it's not the primary driver. The amount of driving I do now, any efficiencies would be offset by some **** with a 2s lawnmower on his/her/its Sunday cut.

Jeepers, you missed that boat decades ago

Yeah I know. Compulsory 'upgrading' hence all the bellyaching. We have no choice (other than to buy a Series 1 I suppose) but to accept all the bells, whistles, knobs and knockers (not stop/start specifically) which add weight, complexity, cost and often, accelerated obsolescence. The cost of trundling all this shit around is real but we're mythering about my reluctance to embrace a 1.5% stop/start saving as the Holy Grail...

That will depend on where you drive/how many times you stop

Yeah I know, but when they (Mert) design stuff, they tend to make assumptions (guess) and take them into account as design/use parameters.

this duty is designed in. (And typically, in a 12v ICE it’ll be around 10-12 times the number of starts, not 1000’s

I meant over the life of the assembly so I'd image a 'normal user' (sorry, there must be a set of useage patterns stuff is designed against Shirley) will do 1000's of extra stop/starts even on Ye Olde 12v systems?

Would be interesting to hear what you think it “non-essential” though

I was thinking more generally about short life/built in obsolescence. Glass dashes for example. How many of the current crop will be scrapped in ~10 years because of a dry joint in their £5k TFT 2 foot long 'instrument cluster' when the cars residual is less? They do it because 'the customer wants it' when actually, it's probably just cheaper to make...

Everything about consumer goods is wasteful

Yeah I know but I choose to repair (within reason) rather than throw away. I buy white goods with 'guaranteed' for 20 years parts availability (whatever that means: 'have a seal Mr Lo, that'll be £1m please...' ). I also try and keep stuff beyond the exciting 'new, new, new' phase and use 'till ferked rather than just spaffing consumerism. If stuff is sold in a way that's inherently difficult to live with longer term, it makes that very difficult. I'm not talking about keeping a car for 40 years but I am thinking it shouldn't be fit for the tip after 10 - like the shit produced in the 70's but for different reasons.

Sigh, I sound like my Grandad. Sorry.

The stop/start went seasonal on my VW when it was about 5 years old (original battery) and gradually got worse until it stopped working completely at about 8 years old.

But I’m a skinflint and didn’t replace the battery until the car failed to start altogether in the depths of winter a year after that.

Stop/start went back to normal with the new battery.

I know some cars drop their rpm to idle levels when coasting – how does that work?

Usually by disconnecting one of the clutches in the gearbox, which clutch depends on if the box has an electric or mechanical oil pump. Problem is that in some cases it saves more fuel to keep the box connected and send the engine to fuel cut (zero consumption) and let the car decelerate very slowly, in coasting, it still uses a little bit of fuel to keep the engine turning over.

tend to make assumptions (guess)

Yeah, it's a bit of WLTP, bit of NEDC, bit of Real Driving Emissions a load of statistical data from test/customer cars. But the definitive thing is always the emissions certification. Hence the 1.5%.
And i can vaguely recall a standard starter is rated for 65 or 75000 starts and the stop start version is something like 300-350000.

They do it because ‘the customer wants it’ when actually, it’s probably just cheaper to make…

TBH, it's both. The customer wants it (because marketing), and we need to do it as cheaply as possible to remain profitable, also, we have to keep up with our competitors, who are also doing it.

And i can vaguely recall a standard starter is rated for 65 or 75000 starts and the stop start version is something like 300-350000.

Interesting to know that. My in laws are convinced stop start will kill the starter motor.

accept all the bells, whistles, knobs and knockers (not stop/start specifically) which add weight, complexity, cost and often, accelerated obsolescence.

I think that a lot of the additional weight increase has come about in the name of safety.