Cars with start/stop engines

ThemFifaGoals

Recently got a new car that has the start/stop engine..apparently it saves fuel, the environment ' all that malarkey. It was a bit weird at first, stopping at lights & having your car cutting out when you put in neutral but you soon get used to it

The other day I got caught in some bad traffic, literally didn't move for 10 minutes or so. I had my headlights, the radio & heating on for that time while the engine was off. Now I understand that the engine only stops if the conditions are right but I was nearly afraid that the battery would die. It didn't, the car restarted when I pressed the clutch in but it got me wondering, would the car restart itself if the battery got to low levels of power? How long can you leave the engine off for while using things like the radio & headlights?

Guy:Incognito

If the battery is below optimal levels the engine wont shut off. It'll start up again well before it gets to the stage that there isnt enough to restart it.

HeidiHeidi

Mine starts up by itself sometimes.

Frightens the bejaysus out of me!

Sh1tbag OToole

I think most systems will start it again periodically. Cars with this will usually have bigger batteries than the standard one. If the battery is new it should last at least an hour possibly 2 or 3 with all the stuff on before it dies

CiniO

How does the heating work when engine is off?

Guy:Incognito

CiniO wrote: »

How does the heating work when engine is off?

From the heat of the engine, same as if its running. It take a fair while to cool down the coolant.It doesnt happen instantly when the engine is turned off.

It'll start up again if it cant maintain the temperature.

CiniO

Guy:Incognito wrote: »

From the heat of the engine, same as if its running. It take a fair while to cool down the coolant.It doesnt happen instantly when the engine is turned off.

It'll start up again if it cant maintain the temperature.

Hmm.
From my experience it doesn't work like that in normal cars. I never had car with start/stop though so maybe it's designed somehow different.

In short heater takes heat from coolant, which is circulating around the engine.
It's circulating, because water pump makes it circulate, but when engine is turned off water pump doesn't work as well.
Effect is, that if you turn off the engine, and leave your heating on, it's literally 20-30 seconds before cold air starts blowing, as there is no more warm coolant circulating through the heater, and coolant which is there already get's cooled down so quickly.

So that's why I wonder if there's any other design in start/stop cars.

ThemFifaGoals

Sounds like you just have to trust the car & it will do the right thing..I was a little wary of it because in my last car, there was a time when I parked up & had the radio on for 20 minutes with the engine off..the battery died & I had to be jumpstarted. I feel more confident in it now having read your replies.

Does it actually save fuel though. I always taught turning the engine on burned fuel or is that nonsense?

bazz26

It's more designed to reduce Co2 emissions under test conditions. I suppose if the engine is shut off then it's purpose is to save fuel and doesn't pollute as much but in the real world from my experience, it saves very little in fuel anyway.

CIP4

ThemFifaGoals wrote: »

Sounds like you just have to trust the car & it will do the right thing..I was a little wary of it because in my last car, there was a time when I parked up & had the radio on for 20 minutes with the engine off..the battery died & I had to be jumpstarted. I feel more confident in it now having read your replies.

Does it actually save fuel though. I always taught turning the engine on burned fuel or is that nonsense?

Sounds like your old car had a battery that was on the way out. A newer car with a decent battery will easily stay an hour with headlights radio etc on and still start up I mean the chances of you sitting that long stopped in start stop mode. But as said above there is safety systems car won't turn off if battery is not properly charged and if it detects the battery running down it will restart the engine well before its flat. The car measures the voltage of the battery itself without necessarily displaying it.

As for does it save fuel stopped for a few minutes yes 30 seconds maybe not so much. Stopped for 10 minutes yes you saved a bit maybe 0.1 l of fuel which is abit a car will burn somewhere between 0.5-1 litre of fuel an hour idling when heated up now that just a broad rough figure.

Toyotafanboi

CiniO wrote: »

Hmm.
From my experience it doesn't work like that in normal cars. I never had car with start/stop though so maybe it's designed somehow different.

In short heater takes heat from coolant, which is circulating around the engine.
It's circulating, because water pump makes it circulate, but when engine is turned off water pump doesn't work as well.
Effect is, that if you turn off the engine, and leave your heating on, it's literally 20-30 seconds before cold air starts blowing, as there is no more warm coolant circulating through the heater, and coolant which is there already get's cooled down so quickly.

So that's why I wonder if there's any other design in start/stop cars.

that might be the case in a crap car, but it's certainly not the case in my experience. it would take a lot more than 20-30 seconds of a piddly little impeller blower to cool down a radiator at 90 celcius to a substantially lower figure.

baring in mind things like heat will travel to cold (basic radiation), so the heat from the rest of the cooling system will continue to offer some sort of heat to the rad, the rad also is in my experience only holding 5-10% of the volume of the cooling system so there should be plenty of passive radiation from the rest of the system.

that combined with the fact that the engine temperature actually increases for a period after the engine is shut off due to the cooling system being effectively shut down means that temps in the cooling should stay up for a reasonable length of time.

that said, i know various premium manufacturers fit a secondary electronic water pump for situations like you suggest.

in response to the OP, when the power in the Astras battery is getting too low, the car will restart itself, it also won't shut itself off in the first place if there is too much of a draw on the electrical system.

corks finest

ThemFifaGoals wrote: »

Recently got a new car that has the start/stop engine..apparently it saves fuel, the environment ' all that malarkey. It was a bit weird at first, stopping at lights & having your car cutting out when you put in neutral but you soon get used to it

The other day I got caught in some bad traffic, literally didn't move for 10 minutes or so. I had my headlights, the radio & heating on for that time while the engine was off. Now I understand that the engine only stops if the conditions are right but I was nearly afraid that the battery would die. It didn't, the car restarted when I pressed the clutch in but it got me wondering, would the car restart itself if the battery got to low levels of power? How long can you leave the engine off for while using things like the radio & headlights?

Yes,car will start itself, if battery is running low,,,,Honda insight hybrid stop/start does anyway

Bigcheeze

Hate these stop start things in diesels. Who wants that shudder through the car every time you start.

Not noticeable in hybrids.

risteard7

Bigcheeze wrote: »

Hate these stop start things in diesels. Who wants that shudder through the car every time you start.

Not noticeable in hybrids.

Can you turn it off/disable it?

colm_mcm

risteard7 wrote: »

Can you turn it off/disable it?

Usually, yes. But any I've seen reset once you turn the car off.

MyStubbleItches

colm_mcm wrote: »

Usually, yes. But any I've seen reset once you turn the car off.

Wife has it in her focus. Button beside the gearstick disables it. It's part of her routine when she starts the car to disable it. This function will undoubtedly lead to turbo and starter problems down the road, especially in cars bought for cheap tax that spend most of their 5k Kms p.a. in towns.

CJhaughey

This isn't new. VW had this on MKII golfs way back in the 80's
Battery tech wasn't as good then so presumably it died out for a while.

HeidiHeidi

MyStubbleItches wrote: »

Wife has it in her focus. Button beside the gearstick disables it. It's part of her routine when she starts the car to disable it. This function will undoubtedly lead to turbo and starter problems down the road, especially in cars bought for cheap tax that spend most of their 5k Kms p.a. in towns.

Part of me thinks this makes some sort of sense.

But surely with this feature being installed in most if not all new cars, it's been tested to destruction by the manufacturers? If there were a serious risk of it damaging engine parts they surely wouldn't have it?

corsav6

HeidiHeidi wrote: »

Part of me thinks this makes some sort of sense.

But surely with this feature being installed in most if not all new cars, it's been tested to destruction by the manufacturers? If there were a serious risk of it damaging engine parts they surely wouldn't have it?

Extra stress on dmf's during startup too, I'd feel more comfortable with it disabled personally.

Sh1tbag OToole

CJhaughey wrote: »

This isn't new. VW had this on MKII golfs way back in the 80's
Battery tech wasn't as good then so presumably it died out for a while.

Didn't Fiat have it as well at one point in the 80's?

We're still using almost the same battery technology as in the 80's so don't know why it died out

CJhaughey

Sh1tbag OToole wrote: »

Didn't Fiat have it as well at one point in the 80's?

We're still using almost the same battery technology as in the 80's so don't know why it died out

Batteries have improved a lot though in terms of energy density and reliability.
Modern ECU's can also determine the state of charge which avoids the non-start problems that probably killed it first time around.

MyStubbleItches

HeidiHeidi wrote: »

Part of me thinks this makes some sort of sense.

But surely with this feature being installed in most if not all new cars, it's been tested to destruction by the manufacturers? If there were a serious risk of it damaging engine parts they surely wouldn't have it?

As far as I can see it's a money making scam. After sales are a huge sector for manufacturers. My wife works for one of the larger manufacturers and after sales kept them going in Ireland over the recession.

bbability

On my fathers Opel Insignia 1.4 TSI. It drove him mad at first. If he hasn't been driving the car for a while it won't activate. He seems to be happy with it although he's not convinced its saving fuel.

air

Toyotafanboi wrote: »

it would take a lot more than 20-30 seconds of a piddly little impeller blower to cool down a radiator at 90 celcius to a substantially lower figure.

If you'd ever actually tried this on a few cars you'd find you're incorrect. As someone else has noted, on cars with a mechanical water pump (the vast majority) the coolant stops circulating when the engine is off. With the blower running, the coolant within the heater matrix soon cools down and without the water pump running there is nothing to replace it. You are correct that there is a lot of heat energy in the total coolant circuit but it's just not available for cabin heating with the engine off.
It would hurt fuel economy anyway if you did cool it all down for cabin heat. The prius even has a thermos that it transfers coolant into to help reduce engine warmup times.

On startstop and battery technology, I believe several models make use of super capacitors in parallel with the battery to reduce the load on the primary battery from the more frequent starting.

fred funk }{

Sure this stop/start thing shortens the life of the starter?

air

fred funk }{ wrote: »

Sure this stop/start thing shortens the life of the starter?

Supposedly the starters are uprated to handle the increased duty cycle, they also use tech to stop the engine at a particular point in it's cycle to ease restarting.

5W30

I absolutely hate this technology.

It also looks stressful for the battery when you're stuck behind a car with auto start/stop and you can see the tail lights dim as it starts.

They should really allow drivers to permanently switch it off.

ednwireland

5W30 wrote: »

They should really allow drivers to permanently switch it off.

i rented an ix20 a couple of years ago and when i switched off the start stop the computer reckoned it was doing more mpg (you could switch it off)

CiniO

air wrote: »

they also use tech to stop the engine at a particular point in it's cycle to ease restarting.

Could you elaborate a bit more about it please. I can't wait to find out what you mean...

Toyotafanboi

CiniO wrote: »

Could you elaborate a bit more about it please. I can't wait to find out what you mean...

i remember reading something before, i have no idea where or how it is carried out, but the concept was that the engine is stopped just before TDC on cylinder one, which should get you the quickest, most efficient restart.

i must admit in the Astra, the restart from the stop start is audibly seamless. you don't hear any cranking, it's like the engine just goes from silent straight to idling. it doesn't sound like a turn key start. so i guess this gives some weight to the optimized cranking position theory

Toyotafanboi

CiniO wrote: »

Could you elaborate a bit more about it please. I can't wait to find out what you mean...

Some Guy On Pistonheads wrote:

To undrestand how it saves fuel, you first need to undersatnd how stop/start systems work (And I can only tell you about the system I know about, so other manufacturer's may do something different)

For a start, the PCM (powertrain control module) doesn't just 'switch off' the engine, it applies additional load to the alternator to stop the engine in one of two positions (either cylinder 1 or cylinder 4 at TDC firing)it then remembers this stop position.

When the clutch pedal is depressed, the PCM flicks in the starter motor, just to get the engine moving.

As the engine was stopped at a point where it was about to fire, and some compression is still left in the cylinder, the PCM then injects a 4 m/s burst of fuel (about twice the amount used by an individual cylinder at idle) and fires the spark plug for that particular cylinder, meaning that the engine starts instantly, essentially starting within 180 degrees of crank rotation (During conventional engine starts, a modern engine doesn't run in normal operation for at least 720 degrees of crank rotation) -At the very worst, the engine will fire within 360 degrees of crank rotation, using a normal injection pulse for the next cylinder to fire

As for battery life, the system I know of runs two batteries of dissimilar capacity. This would normally cause a problem, as charging two different capacity batteries with the same charge current will damage the smaller battery - However, the PCM monitors the battery temperature and voltage of the smaller battery, and disconnects it from the charging system when fully charged or if the battery temp is too high (This is done using PCM controlled relays in the charge circuit)

So essentially, fuel is saved by using a different method of engine starting

air

CiniO wrote: »

Could you elaborate a bit more about it please. I can't wait to find out what you mean...

Did you think I was telling porkies?
The pistonheads guy summed it up nicely, can't imagine it's as easy in a diesel though!

Special Circumstances

air wrote: »

Did you think I was telling porkies?
The pistonheads guy summed it up nicely, can't imagine it's as easy in a diesel though!

I wonder... diesel has more compression and no throttle to contribute pumping losses so it may in fact be easier to get that beautiful diesel starty noise:D

*Kol*

Special Circumstances wrote: »

I wonder... diesel has more compression and no throttle to contribute pumping losses so it may in fact be easier to get that beautiful diesel starty noise:D

I have no idea how it works in a diesel but it's a seamless start in the A4 TDi. I normally turn it off if I am in traffic that has it stopping and starting every 30 seconds. This morning it switched itself off while i was parked but came on again after about a minute, perhaps to keep the heating going?

5W30

*Kol* wrote: »

I have no idea how it works in a diesel but it's a seamless start in the A4 TDi. I normally turn it off if I am in traffic that has it stopping and starting every 30 seconds. This morning it switched itself off while i was parked but came on again after about a minute, perhaps to keep the heating going?

The cheating device falsely detected an emissions testing environment :pac:

billy few mates

I have the start/stop on a petrol VW Golf and the automatic start is practically seamless, you barely notice it starting in the nano second it takes to fire up. I also have the DSG gearbox so when I come to a stop I just flick the hand brake switch and wait, when it comes to moving off I just touch the accelerator and it just moves off, it's effortless, almost like driving a golf buggy. I never switch it off...

colm_mcm

neighbour has a golf 1.2 tsi and it starts up instantly, no audible cranking.

5W30

colm_mcm wrote: »

neighbour has a golf 1.2 tsi and it starts up instantly, no audible cranking.

Being a petrol and a small light engine helps

sunnysoutheast

We have a BMW and Audi both auto with stop/start. Took a while to get used to it but it's second nature now. Take your foot off the brake and off you go. Fairly easy to anticipate when it will be a pain in queuing traffic so I just deactivate it when needed.

I think somebody on here posted a while back that the systems aren't a major reliability headache based on their fleet experience.

In the US you can apparently get a BMW coded to "remember" the stop/start setting between switchoffs, but not in Europe.

CiniO

Toyotafanboi wrote: »

that might be the case in a crap car, but it's certainly not the case in my experience. it would take a lot more than 20-30 seconds of a piddly little impeller blower to cool down a radiator at 90 celcius to a substantially lower figure.

baring in mind things like heat will travel to cold (basic radiation), so the heat from the rest of the cooling system will continue to offer some sort of heat to the rad, the rad also is in my experience only holding 5-10% of the volume of the cooling system so there should be plenty of passive radiation from the rest of the system.

that combined with the fact that the engine temperature actually increases for a period after the engine is shut off due to the cooling system being effectively shut down means that temps in the cooling should stay up for a reasonable length of time.

Sound rational in theory, but it doesn't work like that in practice.
Take any random car, warm it up, put max temperature and blower fan on, and turn off the engine (but keep the ignition on so the fan can run). I can guarantee, it will be less than a minute when cold air starts blowing.
Me living in fairly cold climate for many years, had a chance to try it on variety of cars, and that was always the case.
Just try it yourself on your car.

that said, i know various premium manufacturers fit a secondary electronic water pump for situations like you suggest.

That could obviously help to use heat accumulated in the whole coolant, instead of just small bit of it in coolant actually located in heater element.
But can you point any examples of cars which have such pump?

air wrote: »

If you'd ever actually tried this on a few cars you'd find you're incorrect. As someone else has noted, on cars with a mechanical water pump (the vast majority) the coolant stops circulating when the engine is off. With the blower running, the coolant within the heater matrix soon cools down and without the water pump running there is nothing to replace it. You are correct that there is a lot of heat energy in the total coolant circuit but it's just not available for cabin heating with the engine off.
It would hurt fuel economy anyway if you did cool it all down for cabin heat. The prius even has a thermos that it transfers coolant into to help reduce engine warmup times.

That confirms my experience in this regard.

CiniO

air wrote: »

Did you think I was telling porkies?
The pistonheads guy summed it up nicely, can't imagine it's as easy in a diesel though!

I must say I did.
I'm converted now - so much new technologies which I'm not aware of yet.

Eric Cartman

CiniO wrote: »

Hmm.
From my experience it doesn't work like that in normal cars. I never had car with start/stop though so maybe it's designed somehow different.

In short heater takes heat from coolant, which is circulating around the engine.
It's circulating, because water pump makes it circulate, but when engine is turned off water pump doesn't work as well.
Effect is, that if you turn off the engine, and leave your heating on, it's literally 20-30 seconds before cold air starts blowing, as there is no more warm coolant circulating through the heater, and coolant which is there already get's cooled down so quickly.

So that's why I wonder if there's any other design in start/stop cars.

secondary electric pump , my e38 has one and even with the engine off I can engage 'rest' mode on my climate panel and get lovely hot air (20 minutes is the longest I've used it and it was still hot then, can't vouch for how long it would stay)

Toyotafanboi

CiniO wrote: »

Sound rational in theory, but it doesn't work like that in practice.
Take any random car, warm it up, put max temperature and blower fan on, and turn off the engine (but keep the ignition on so the fan can run). I can guarantee, it will be less than a minute when cold air starts blowing.
Me living in fairly cold climate for many years, had a chance to try it on variety of cars, and that was always the case.
Just try it yourself on your car.


That could obviously help to use heat accumulated in the whole coolant, instead of just small bit of it in coolant actually located in heater element.
But can you point any examples of cars which have such pump?

I recall a member on here replacing such a pump in their new-ish 7 series. Can't remember who exactly. I think, but i'm not 100% that Rover 75's have it too?

I've never tried it with my own car, I was more applying it to something similar to thermostatically controled central heating in housing, where the system would go dead and stop circulating but you would still get good convection/ radiation from the rad for a good long time before it cools. Now I know a household rad is much bigger but compared to the space it's heating etc it's similar. I'lkeep an eye to it during the winter in the Astra.

*Kol*

5W30 wrote: »

The cheating device falsely detected an emissions testing environment :pac:

I did laugh out loud when I read that!!

Toyotafanboi

CiniO wrote: »

Sound rational in theory, but it doesn't work like that in practice.
Take any random car, warm it up, put max temperature and blower fan on, and turn off the engine (but keep the ignition on so the fan can run). I can guarantee, it will be less than a minute when cold air starts blowing.
Me living in fairly cold climate for many years, had a chance to try it on variety of cars, and that was always the case.
Just try it yourself on your car.


That could obviously help to use heat accumulated in the whole coolant, instead of just small bit of it in coolant actually located in heater element.
But can you point any examples of cars which have such pump?

I recall a member on here replacing such a pump in their new-ish 7 series. Can't remember who exactly. I think, but i'm not 100% that Rover 75's have it too? A secondary water pump was the term I think.

I've never tried it with my own car, I was more applying it to something similar to thermostatically controled central heating in housing, where the system would go dead and stop circulating but you would still get good convection/ radiation from the rad for a good long time before it cools. Now I know a household rad is much bigger but compared to the space it's heating etc it's similar. I'lkeep an eye to it during the winter in the Astra.

Eric Cartman

also some of these cars (particularly diesels) could have a webasto parking heater which will heat the cars coolant from fuel.

Jesus.

Just hired out a Peugeot 5008 diesel. It cuts out even when I pull up at a yield sign for like 2 seconds. Is this what Stop/Start technology is all about? I thought it might only happen after being pulled up for a few seconds but not like this. The car is also beeping any time I pull up behind another car in traffic (not on his bumper).

Surely this isn't normal behaviour for a car. Should I bring it back?

MuppetCheck

Beeping could be the parking sensors.

Once the conditions are met the stop/start will work. Leave your foot on the clutch if you're going to a yield sign. Simples.

Jesus.

MuppetCheck wrote: »

Leave your foot on the clutch if you're going to a yield sign. Simples.

With the greatest of respect Muppet, fu*k that!

Can it be disabled easily?

TheChizler

Jesus. wrote: »

With the greatest of respect Muppet, fu*k that!

Can it be disabled easily?

You're hardly going to put it in neutral at a yield sign?

dar83

Jesus. wrote: »

With the greatest of respect Muppet, fu*k that!

With all due respect who puts the car in neutral at a Yield sign?!

There should be a button somewhere either on the dash or in the centre console to turn it off. You may need to hold it for a couple of seconds or just press it once, not sure how it works on a Citroen.

The parking sensor beeps sound a bit over enthusiastic though, I've not had that experience unless I stop in traffic and then move slowly forward and also be a bit too close tonhe car in front. Even at that you can disable them by press the parking sensor button (which should be close to the stop start one if its anything like the Golf).