As for stop/start we've only one vehicle with it fitted. It worked for about two weeks when I fitted a new battery, hasn't worked since, I won't be spending money to find out why.
Modern 'smart' alternators need syncing with their batteries in order for the system to work optimally. My understanding is that if the stop/start isn't working it's a sign your alternator doesn't know that you fitted a new battery. That could mean it's overcharging your battery affecting its longevity.
YMMV.
As I understand it that's exactly what it needs. I enquired at the local Merc dealer at the time, to be told they'd need to scan it first to check what work needs doing, that'll be a large chunk of money +vat please, and that'll sort it? No, then will book it in to have the work carried out, for more money.
Hard pass thanks.
That was 3 years ago, no ill effects for the van, or my wallet since.
@submarined. interesting explanation and like others I often disable mine when I get in the car (2019 C class) As someone who considers themselves quite mechanically sympathetic I have had the concern that starting and stopping the engine (sometimes within seconds) can cause wear. As you say I reassure myself (as with lots of things) that there are a lot of clever people designing these systems who know much more than me but the system on my car can literally stop and start a couple of times within a few seconds as you slow at a give way for example.
Edit: its also a mild hybrid that turns everything off except ancillaries when driving. The first time the engine cut out at 70mph on the motorway was a bit disconcerting...
Our Honda Jazz does the auto stop/start thing when idling in neutral (so, sitting at lights etc). Lately it's not been doing it, and I suspect it's because it's being used for a lot of short journeys so the battery isn't getting a proper charge.
I figured it would do no harm to stick on a battery charger overnight. I have a charger, I presume I can just connect it and let it do it's thing, there's nothing I need to bear in mind cos of the stop/start shenanigans?
Yeah short trips kill those stop start systems, they’re super picky about battery health. Slapping it on a smart charger overnight is totally fine, just make sure it’s AGM compatible if your Jazz uses that, otherwise you’re kinda wasting time. Honestly though, if it keeps happening, battery might already be on its way out, those systems drop out fast when voltage dips even a bit.
@submarined. interesting explanation and like others I often disable mine when I get in the car (2019 C class) As someone who considers themselves quite mechanically sympathetic I have had the concern that starting and stopping the engine (sometimes within seconds) can cause wear. As you say I reassure myself (as with lots of things) that there are a lot of clever people designing these systems who know much more than me but the system on my car can literally stop and start a couple of times within a few seconds as you slow at a give way for example.
Edit: its also a mild hybrid that turns everything off except ancillaries when driving. The first time the engine cut out at 70mph on the motorway was a bit disconcerting...
I assume that's a parallel hybrid? Essentially both the engine and motor are connected to the gearbox via a clutch so the car can select drive from one, the other or both at any time so it can cut the engine whenever it's not needed (i.e. when coasting). The startup procedure on those is actually pretty clever, the car puts power through the electric motor, then uses that to spin up the engine, which makes sure the oil is primed etc, then after a few cycles it starts injecting petrol to make sure the cylinders are 'wet' (not in a way that would wash fuel into the oil, you just don't want it to be lean when it starts up), then a couple of cycles after that it starts to fire. It's a bit more involved than the way old cars started up by just doing everything at once until it started after a random number of revolutions.
I thought the term "mild hybrid" was more often used to describe things like the Ford system though which is basically beefed up 48V alternator/starter/motor driven off a belt, sort-of replacing the need for a turbo on a small engine?
Back in the early days of hybrids Honda made the Insight with a series hybrid drivetrain, which was actually better in a lot of ways as everything was permanently engaged, but the Prius won out with it's party trick of being able to drive round the car park with the engine off.
Regardless of that I'd not worry about the engine stopping and starting. How many people do you actually know who've worn out an engine in the last 30 years?
Our little Fiesta that we've had from (almost) new is now on 185k miles, the OH rags it on the motorway flatout with zero mechanical sympathy, it has always used a little oil between services and she never checks it until it gets noisy so it's been run dry a few times. It's only ever been serviced with whatever oil and filter was cheapest and met the spec at ECP. The only thing I can point at and say it's been a problem because of short journeys is the exhaust keeps rotting as it's obviously full of condensation (and I only ever buy the cheapest <£100 full system because it's cheaper to keep thawing a new one one than pay for the nice OEM ones!).
Modern cars are just so well built that unless there's a specific fault, they just don't wear out like they did. Even wet-belts or 7mm cam chains. Imagine telling someone in the 80's that their engine would do 70,000 miles on nothing more than an oil change and they might need some inspections/preventative maintenance after that. They'd laugh at you and go of to adjust their tappets.
I know the systems are supposed to be designed for multiples more of stop/starts but they would say that wouldn't they...?
You're in the wrong thread. Here:
https://singletrackworld.com/forum/off-topic/conspiracy-corner
Mine's staying off unless my use pattern changes.
I'm not so sure. There's 1000's upon 1000's of YouTube vids covering premature failure of engines and early retirement of cars due to repairs not being economically viable. Certainly, the majority don't seem to wear out or suffer tin worm in the way they once did but try buying a digital dash for a 10 year old car. It'll be a write off. Cars don't need tappets so much now but they do need induction manifold cleaning due to being gummed during direct injection or they need a DPF/DMF/EGR/PCV or some such or even some horrible plastic parts that's failed because (surprise, surprise) plastic is not great for extended duty involving many, many heat cycles and/or impact. Aye it's cheap to produce alright but beyond the usual 3 years warranty, hmmmm.
It's not wonder people are moving to mobile white goods its just a shame the depreciation curve is cliff like.
my Jazz is 6 years old and basically doesn't do it when the weather is cold.
Anecdotally, I've seen the opposite too. The stop doesn't occur if it's 30'C outside and the aircon is belting its tits off.
It's almost like someone thought not to cut off the alternator when battery load is high, or something.
Presumably stop/start architecture can differ by manufacturer?If you're in a V90 it's got two batteries. There are probably 20 different architectures for stop start. Some have one, others have two.
Really! That's a load of rubbish. Emission tests are based on the engine running which it's not while stopped.No, they aren't, current emission cycles stop the engine 5 or 6 times in the ~20 minutes they take to run. I say current, but they've been like that for at least 15 years.
I know the systems are supposed to be designed for multiples more of stop/starts but they would say that wouldn't they...?Yes, I do. Failing starters are really bad, as they are a pig to replace, and the on cost for the upgrade (on a 12v system) is pennies. (Going to a 48v system isn't pennies, but it can do loads more!) The suppliers are also keen to *not* have starters fail. As they have to pay for those that fail *in* warranty, and all of the failures (all those thousands that are being hidden from us) give them a bad reputation.
It's almost like someone thought not to cut off the alternator when battery load is high, or something.At last count the system looks at low double digits of signals before deciding if it should shut off or not.
Maybe a bit late but... I've a Ford Kuga that historically chews batteries (on its 4th in 8 years - 2nd one for me in the 4 years Ive had it).
We've been away over easter camping, and that does the battery in, as loads of stuff livens up every time the door is opened (all interior lights (and can'tbe turned off), front and rear marker lights, display, computers etc). So has to use the Noco jumper pack 2 or 3 times in the week away. One of the most used £200 spends I have !!
The current Varta battery was fine for working the auto stop-start for about 5 months from new . Then nada for the subsequent 20 months. My driving is mixed - some short stuff, but plenty of 10-20-30 miles, and the odd properly long trip in there too - eg round trip to see the daughter is 500+ miles.
Anyway after a 6hr / 300 mile drive home in traffic etc, low and behold, not only was Jesus resurrected from the dead on Easter Sunday, but by the end of Easter Monday my car battery seems to have been resurrected from the dead too. Its back to working the auto stop-start !
I assume that's a parallel hybrid? Essentially both the engine and motor are connected to the gearbox via a clutch so the car can select drive from one, the other or both at any time so it can cut the engine whenever it's not needed (i.e. when coasting).
I doesnt power the car. If I lift off the engine cuts out and everything stays on but the car starts to slow.
@mert. Nailed it.
All I can add is that there are often 2 catalogue references for a starter motor for the same vehicle - S/S model and standard model. They beef up the starter on a S/S version.
someone says ~3% improvement in emissions and presumably a bit in fuel consumption? A few years ago, I turned off the air-conditioning over winter to 'save' fuel. All good until I turned it back on and it leaked due to dry seals or some such. Cost a couple of £k to sort - dashboard out etc. An example of well intentioned actions costing more in the real world.
You're comparing what you, as an amateur, decided to do off your own bat and against long-standing advice to a system designed by several manufacturers...and deciding they're all equally useless?
https://www.rac.co.uk/drive/advice/car-maintenance/air-con-myths-busted/
You're comparing what you, as an amateur, decided to do off your own bat and against long-standing advice to a system designed by several manufacturers...and deciding they're all equally useless?
I'm deciding what I do based on the direct costs I may face putting right issues that may be encountered after following the advice of the experts. On the aircon, the advice at the time was to switch off to save fuel.
Air-con is another feature that I'd rather live without.
It's very rare that'll use it. Last summer was stupidly hot.... 39°C in the shade here in Italy. Used it a bit then, but I honestly prefer to open the windows and get a bit of a breeze in..... I'm driving around in a 3,5t van. It's very rare that I'll drive faster than 100km/h. I think, in my case, the aerodynamic saving of having a window open is negotiable.
Would rather do away with another potential fail point.
Having air con running can prevent stop/start too I think.
....
Yeah short trips kill those stop start systems, they’re super picky about battery health. Slapping it on a smart charger overnight is totally fine, just make sure it’s AGM compatible if your Jazz uses that, otherwise you’re kinda wasting time. Honestly though, if it keeps happening, battery might already be on its way out, those systems drop out fast when voltage dips even a bit.
....
Jazz is 6 years old and basically doesn't do it when the weather is cold.
It's on the original battery. It's currently doing plenty of motorway work (450 a week plus local running) and I'd expect the battery to be as good as it can be.
The S/S system clearly monitors the battery. If the battery state is poor (short journeys, lots of S-S, old battery, lots of drain eg zircon in summer, screen heaters on in winter, I think even high ventilation fan speed) it's less likely to activate. Once you've driven for a while and the battery charge is sufficient it starts working again.
From the RAC - "Car batteries typically last between 3 and 5 years. While some can last up to 6 years, 3–4 years is the average lifespan before they start to fail or require replacement."
I'd *guess* based on how all other batteries get killed that how you use a vehicle will affect the life - with both a lot of use and weird patterns of use where the car gets driven rarely both reducing life but I'm not a lead acid battery expert and they may behave differently.
I replaced the battery in our Caddy yesterday. It was the battery that was in it from new I'd guess (we got it at a year old) which means it's done 8 years. Stop-Start was only working after it had been driven recently. Left for a few days and it wouldn't be doing it at the start of drive. That actually seems a really good failure mode to me - much better than failing to start.
That reminds me of the Audi A3 auto I had as a courtesy car last year. Was around 2010 vintage I think. Pulled up to a junction, foot on brake.. stop start kicks in. Not in neutral or park, still in drive just pulled up to a junction. Felt so wrong and bordering on dangerous that I had to turn it off every time I got in the car.
That is literally how stop-start works in an auto. As soon as you take your foot of the brake the engine starts. If you're really worried about the time it takes to restart the engine releasing the brake and putting your foot back on it will restart the engine immediately (and I think it doesn't stop again until some time has passed or the car has moved - not sure - it just works). Very very occasionally, an I think usually in car parks or slow speed manoeuvring, ours gets confused and you have to put it in park and manually restart. Rare, and I've not worked out what triggers it.
I really like the silence and complete lack of vibration when stationary. It's also much nicer being on the pavement or on a bike alongside or behind vehicles that don't have their engine running spewing out fumes.
That said, I've never driven with it on a manual - is it more intrusive then? (I can't imagine ever choosing to drive a manual again though)
That said, I've never driven with it on a manual - is it more intrusive then? (I can't imagine ever choosing to drive a manual again though)
In a manual it does it whenever you put the car in neutral and take your foot off the clutch. It usually starts again in the time it takes you to push the clutch down.
If you're REALLY violent with it, you can get it in gear and take your foot off the clutch while it's still trying to start, but the only people I've seen stall/kangaroo off the line like that are the ones that are on their phones. Any normal person it's un-noticeable doing it while the lights go amber.
That said, I've never driven with it on a manual - is it more intrusive then? (I can't imagine ever choosing to drive a manual again though)
In a manual it does it whenever you put the car in neutral and take your foot off the clutch. It usually starts again in the time it takes you to push the clutch down.
If you're REALLY violent with it, you can get it in gear and take your foot off the clutch while it's still trying to start, but the only people I've seen stall/kangaroo off the line like that are the ones that are on their phones. Any normal person it's un-noticeable doing it while the lights go amber.
Yeah I'd say it's decent on most manuals I've driven. Because you've actually put it into neutral there is that natural command over the system so it pretty much works exactly as you would want it to.
On the other hand my biggest beef with the system on my auto (DSG) is that it cuts the engine at approx 5 mph. So in heavy traffic, if the speed briefly dips below 5mph and then speeds back up, it will stop and then have to restart the engine a split second later. Sometimes this causes quite a noticeable delay/thump through the drivetrain as it gets its act together.
It's almost like someone thought not to cut off the alternator when battery load is high, or something.
Amazing isn't it. Start/stop already tuned to work when it makes sense, and automatically disabled when it doesn't it. Yet people permanently disable it... because they like to be "in control". Anyway, our tiny car doesn't do start stop when really cold. It does when warm. I'm a windows open over air con person though. Which ironically I can't always do when queuing in urban areas in hot weather because everyone else has their engines permanently on...
On the other hand my biggest beef with the system on my auto (DSG) is that it cuts the engine at approx 5 mph. So in heavy traffic, if the speed briefly dips below 5mph and then speeds back up, it will stop and then have to restart the engine a split second later. Sometimes this causes quite a noticeable delay/thump through the drivetrain as it gets its act together.
My A6 did that, it was bloody annoying and didn't feel terribly safe coasting to standstill with the engine not running.
My A6 did that, it was bloody annoying and didn't feel terribly safe coasting to standstill with the engine not runningYeah, we actually thought about that when we designed the system... Surprisingly.
I got the A6 after a BMW that did stop start properly. I actually thought the A6 was faulty at first and had to check with the dealer that it was supposed to do that.
My A6 did that, it was bloody annoying and didn't feel terribly safe coasting to standstill with the engine not runningYeah, we actually thought about that when we designed the system... Surprisingly.
Painful, isnt it @mert. Its like reading advice about bikes on a motoring forum 🤣
There isnt a single, even half an argument here that, unbelievably, hasnt already been considered by the hundreds of design, mechanical, software, manufacturing, reliability Engineers that made your car.
"My S/S cuts in whilst the car is still in drive"
The gearbox drops into false neutral.
"The S/S doesnt work when the heated seats are on turbo, the wipers are going like billy-o, the lights are on and the air con is flat out"
Yeah, funny that...
"The S/S cuts in before I've come to a complete halt, thats dangerous!"
There is a vacuum pump and accumulator providing you with brakes and the power steering is by electric motor directly on the column
"Its never hot enough to use A/C in this country"
Your one of those people driving along the motorway in winter with all the windows steamed up, arent you?
"I read one article about soemthing called a 'wet belt' on the internet and now I've decided its the worst thing to hit society since the plague"
But you quite like that lovely quiet running smooth and economical engine dont you? Wouldnt fancy a CVH knocking away in your Fiesta in 2026 I'm betting?
"My mechanic told me he only sees these models when they are broken"
The less said about that statement the better here. If mechanics designed cars, they would be absolutely, unbeleivably, awful.
etc etc etc.
"I read one article about soemthing called a 'wet belt' on the internet and now I've decided its the worst thing to hit society since the plague"
But you quite like that lovely quiet running smooth and economical engine dont you? Wouldnt fancy a CVH knocking away in your Fiesta in 2026 I'm betting?
So the only options are a modern engine that clogs its own oilways or a 40+ year engine design?
There's going to be a lot of modern cars with these types of engine going to an early grave as they just wont be economically viable to repair. Plenty of other manufacturers manage to design reliable modern engines.
"I read one article about soemthing called a 'wet belt' on the internet and now I've decided its the worst thing to hit society since the plague"
But you quite like that lovely quiet running smooth and economical engine dont you? Wouldnt fancy a CVH knocking away in your Fiesta in 2026 I'm betting?
You can file wet belts away in the same "industry innovations" folder as stopping the engine before the car has stopped to save 0.2g of CO2 on the test cycle and burying critical functions three levels deep on a touchscreen to save 20p on the BOM.
It's shite engineering that doesn't benefit the owner of the vehicle.
I've personally scrapped a car that was less than 10 years old because of premature wet belt failure (yes it was serviced on time with the correct oil).
Just imagine how much embedded CO2 has been squandered on that single car.
Now multiply that across all the Puretechs and Ecoboosts that have shat themselves in the same way.
Yeah, I don't really appreciate the sneary 'we know better' posts from the industry 'experts'. You may be experts in your field but have no responsibility/liability for the longer term implications of some of the decisions you implement. We (your customer, so a bit of respect please) bear those. So forgive me (us) if we don't blithely applaud every 'innovation' that makes the product harder to use, less reliable and more costly over its (diminished) life time.
TBH, i'm not sure what the thought processes behind dipping a polymer/EPDM/synthetic rubber belt running at high speed and load in hot oil actually were. Even writing it down sounds weird.
That would almost certainly fail the very first stage of a properly done risk analysis. Hell, we spent the first 3 decades of belt driven ancillaries making sure they *didn't* get sprayed with oil.
I mean, i know what the reason is, engines are getting noisier and more clattery due to DI and lighter weight construction. A belt is at least quieter. And cheaper than using proper sound deadening and smart/active mounts, or a properly isolated chain. Which is what a lot of other manufacturers do instead.
as stopping the engine before the car has stopped to save 0.2g of CO2 on the test cycleThe tech/strategies used to stop the engine while moving are also used for sailing and coasting (which usually sits in the same part of the powertrain management structure as fuel cut out).
The stopping at 5-7-10 kph probably doesn't even save 0.2 grams on the test cycle, but does save actual real fuel in real driving when the full suite is used properly. But it's complicated to implement without having clonks on start up when the gear re-engages. Or making customer panic as the engine has just shut down at 90kph.
Think there used to be emissions credits for stopping at speed in the US and any other market that follows US structure as well (which is why every man and his dog implemented it as quickly as they could.)
On the aircon, the advice at the time was to switch off to save fuel.No one in the industry in the last 25+ years has suggested shutting the AC off to save fuel. More likely an expert on the internet.
Yeah, I don't really appreciate the sneary 'we know better' posts from the industry 'experts'.Stop posting garbage about how you think stuff works based on rumours and hearsay then? Some of it should be in the Conspiracy Corner.
Painful, isnt it @mert. Its like reading advice about bikes on a motoring forumTo be fair, it's more the new generation of auto journalists, commentators and "influencers" who have managed to get themselves a veneer of respectability through some means or other (these days it's probably slick tiktok/IG videos these days) who really have no idea what they are talking about. Just regurgitating half truths and deliberate misunderstandings to get clicks.
It's probably more than half of the market by now.
The automotive equivalent of laterally stuff and vertically compliant, or maybe it's the other way round. I'm not sure anymore.
t's more the new generation of auto journalists, commentators and "influencers" who have managed to get themselves a veneer of respectability through some means or other
As an expert in a very different field that gets even more stick than yours I wholeheartedly agree.
A video of a healthy Ford Focus having it's wet belt routinely changed after a life of rigorous maintenance does not make for Likes and Comments.
Whereas a ropey one that's been thrashed and neglected and has snapped or deteriorated and clogged the oil pipes does. They're then represented as another **** Focus wet belt issue because it pays the posters (often garages/mechanical businesses) to represent them that way.
I am not picking on the Focus, quite the opposite, our 13 year old wet belt, (not) exploding EcoBoost that we've had for 9+ years is great.
Yeah, I don't really appreciate the sneary 'we know better' posts from the industry 'experts'.
The thing is, you're extrapolating a completely unrelated reliability issue, driven by a completely different business need, to decide not to trust something that benefits a lot of people. Where does that stop? How can you trust the steering system by the same logic? The brakes? Fair enough if there was hoards of reports of failing starter motors and premature engine wear but there's not. It seems fair that people might be insulted by being tarred with one broad ford shaped brush for work they are proud of.
Yeah, I don't really appreciate the sneary 'we know better' posts from the industry 'experts'. ... We (your customer, so a bit of respect please)
They do know better. Us consumers are complete ****ing idiots. Cars are obsessively engineered to stop us doing patently stupid things or lessen the consequences of doing them.
Us consumers are complete ****ing idiots.
You only have to go shopping to conclusively prove this. I'm often left pondering how the shambling fu@kwits wandering around your average supermarket managed to get themselves there.
Auto stop start is not there primarily to save energy. Its there to stop killing pedestrians and cyclists by the pollution cars create when sat in traffic jams. Disabling it is a complete dick move. It make a huge difference
Its there to stop killing pedestrians and cyclistsYeah, we try that with loads of features, crickets.
"It'll save you tuppence ha'penny a month"
All over it...
On the subject of stuff in cars failing early, I've just paid a chunk of money to have the screen replaced on a 2018 VW head unit. Touch sensor failure in these is incredibly common apparently (and evidently - see pics). VW don't repair, and a replacement is getting on for £3k (!).
the place we went to told me 90%+ of their work is VW head unit repairs now (used to be 90% upgrades/installs). The pile of 'main units' from cars with separate screens is 2 deep!
Us consumers are complete ****ing idiots.
You only have to go shopping to conclusively prove this. I'm often left pondering how the shambling fu@kwits wandering around your average supermarket managed to get themselves there.
TBF most of them spend more time in the car park than the shops, performing 90-point turns to get out of parking spaces because they can't see any corner of their car so seem to think it's the length of an aircraft carrier.
Stop-start will obviously reduce fuel consumption/emissions. My understanding is that the emissions 'scandal' or whatever with VW was that they programmed the engine management to reduce fuel use at a narrow power/speed (whatever) band - at which the testing was done.
It only affected diesel engines anyway, not petrol engines like I have in my Ford, on which the auto stop/start gave up the ghost several years ago, and I can’t say I’m that bothered about it. The car is a 19-plate, and IIRC it’s still got its original battery. Starts perfectly every time, so 🤷🏼♂️
