start stop issues

[SuperV8]

On climate change and the rest,
You can measure yourself how much co2 is in your local atmosphere.
Here's a speriment for you to do.
Get co2 meter, go into the garage, shut the door and measure the concentration write it down.
Run the engine in the garage for 30 mins and take another reading. You can then see what your car can do to a relatively small volume.
Co2 can be measured historically from ice cores and others so actual we not only know how much co2 there is but also how much there was.

Emissions by sector: where do greenhouse gases come from?

Where do greenhouse gases come from? How much comes from electricity, transport, and land use?

ourworldindata.org

Here's a good source of all sorts of stats.

Acid rain was a thing, another thing was done and now it's not.
The hole in the ozone layer, again an actual thing, the cause identified, the way we did things was changed and now the hole is very much smaller and shrinking.

All these things are researchable while you're sat on the toilet. Actual science is available to all who can understand it.

It is problematic however that much of science requires understanding and that many people don't have let's say a science brain.
The COVID thing is a case in point, the ppl with degrees and experience try to give ppl with a limited grasp of anything scientific information to decide the right course of action.
A herd of ppl is a daft unpredictable thing, get one person and you can usually get the message across. Usually

One of the issues I think is the units the scientists are using in predicting temperature change - like one or two degrees global average warning means bugger all to most people - thinking so what!
A very interesting stat I herd which helped me conceptualise it, from a climate scientists was something like (don't quote me) - the last time the earth was in an ice age when the oceans were frozen over, the average temperature was ONLY 5 degree cooler! so yes only a few degrees average global temperature change can have very big effects.

Also found 'potholer54' YouTube channel very interesting

 

[Walone]

Hi all

getting to grips with the new(to me) 2.0tsi 190 dsg.
Start stop is doing some weird things.
It used to work quite often once it had warmed up.
Recently it wasnt working so, at the traffic lights I turned it off and turned it on again and the system kicked in straight away.
Yesterday on a longer journey ( no air con on) I couldnt get it to kick in at all.

Today the same thing, but somehow it showed a message.
whilst driving it said power consumption too high, when i was in traffic it said " engine needs to be running" It was.

I checked the battery on OBD11 and it said it was fine.
Any ideas what could be causing this?

Thanks in advance

Well, I parked my car at the airport for six days, since then the start/stop seems to be working too well!! Within 2 or 3 minutes leaving my garage today the start/stop worked, really strange, it's always worked quite well, but this is too well !! Original battery 7 1/2 years old.

 

[RUM4MO]

I've always initially, found that the auto Stop/Start was being enabled extremely quickly in my wife's August 2015 VW Polo 1.2TSI 110PS 6MT, but frequently I intervene and allow it to function only when I decide it should!
That car at 43K miles is still on its original EFB battery, although I thought it needed "sort out" maybe a year ago, and after running a re-con program on the CTEK smart charger, I re-reg'd the battery and it seemed that doing that stopped the battery being heavily re-charged at all times - I have a plug in 12V DVM so that I can keep an eye on the charging level.
I've found that the way that you drive the car can affect the way the battery gets charged - or otherwise drained/used, so that means driving the same journey smoothly/granny style, can easily lead to the battery getting used/drained, whereas, for the same journey at the same time of year, driving more "firmly" always means that the battery gets "filled" up so auto Stop/Start is normally always available, obviously the "smooth/granny" driving leads to better MPG but not much in the way of auto Stop/Start and driving more "firmly" leads to a slight reduction in MPG but auto Stop/Start is always available. So while auto Stop/Starts must lead to reduced emissions at certain points in my journeys, the overall emissions are higher - no surprises there then!

 

[andylong]

To know the state of charge (SOC) of the battery you'll have to disconnect it. Small loads will drag the voltage down down and a running engine will charge it. Charging circuits will predict the battery full based on charge acceptance and battery type.
Reregistering an old battery will reduce expectations from the charging circuit so it will never fully charge to previous levels.
In the case of efb and AGM, they are designed to work better at sub optimal SOC and so will last longer.

Alternators can produce more power with more revs, but they respond to load so to maintain output voltage they increase field voltage so you get more power at the same revs or potentially the same power you could get at higher revs with less field current.
Whilst it might be difficult to believe, alternator output is substantial at idle, it has to be, electrical load of the vehicle doesn't rise much with engine or vehicle speed you'll see your DVM up at 14.2 ish volts right away on start up. If your voltage is 14.2v your battery will charge as much at 14.2v at idle as it will at 5000 rpm.
There's a link below but essentially the bulk of alternator output is available from 1000 revs.
Driving style can't affect battery charging in way you suppose unless your battery or alternator system are faulty in some way.
The length of time spent charging will tho, but if you battery voltage drops stop start stops.
Dynamos are different, but alternators respond to current demand by in creasing the winding current to create more power and decreasing it as it spins faster. There's a limit ofcourse.
Once the engine is started the battery's job is over, it's all down to the alternator.
If the load at idle from the alternator slows idle then more fuel gets used to maintain idle but this is the same for all vehicles using an alternator.

Alternator Output Curves - Balmar

Alternator Output Curves Alternator output is dependent on a number of factors: battery condition and capacity, wire size, engine horsepower and engine RPM, battery temperature and alternator temperature. Of these factors, alternator speed and temperature are the most important. The following...

balmar.net

 

[Matt_anderson]

You buy that?

Take the starter for instance. Yes, they make the starter better quality but how many more starts does a stop-start starter do? Ten times more? Is the starter ten times stronger? And the system does not wait until the engine is up to temperature before it kicks in. If you drive in town you could be looking at three of four times the number of cold starts.

Stop-start is like a lot of other things that were introduced to tick a box and get brownie points. I'd rather uses fractionally more fuel and keep the engine running. By the way, I track my actually fuel usage for both of our cars and have done for decades. Having the stop-start active or disabled made no noticeable difference to the MPG. Maybe it would if you sit in traffic for hours.

Out of interest, why have you tracked actual fuel usage for years?

 

[Mr Pig]

Out of interest, why have you tracked actual fuel usage for years?

I can't remember why I started doing it. I think I wanted to see if there was any economy difference between regular and super unleaded maybe? The only car I've had that got more MPG out of super was a Nissan Primera GT. Once you get into the habit it's very easy.

Brim the tank, reset the trip counter. Next time you fill up, brim the tank again and make a note of the fuel that goes in and the miles you've done and work out the MPG when you get home. I keep a note of it on my service record.

The MPG you get from a tank can vary quite a lot and you get to see trends. It's an easy and useful thing to do.

 

[RUM4MO]

For me, it just makes sense to record fuel usage along with the distance run - very much the same as keeping records month to month of home energy usage, both allow you to spot if/when something has changed enough to be of concern.

Also, with modern cars having fuel computers, it is even easier than it used to be when you needed to work out your own figures, okay maybe the car's fuel computer could be less accurate, but as long as the %age error is constant then the recorded data is still very relevant.

 

[Mr Pig]

Also, with modern cars having fuel computers, it is even easier than it used to be when you needed to work out your own figures..

From comparing them to manually working it out I've found that the computer is not very accurate. I know, you'd think it would be? But it doesn't seem to know, it's just guessing. It's like the fuel gauge, it's only approximate.

I've been doing this for decades now and it takes no time at all. Too easy to not do it.

 

[andylong]

It should be very accurate, mines not but still useful I find. Presumably the fuelling or the sums are wrong.
I guess what matters is how you use what is a tool.

 

[SteveGSXR600K1]

I use the Fuelio app to record my fill-ups. The average MPG that Fuelio generates compared to what the car generates is usually 2-3 MPG under. Keep meaning to look into an adjustment you can make using OBDeleven, to make the cars calculation more accurate.

 

[andylong]

I wonder if the over reading of speed carries over to the odometer etc

 

[mjj4]

I wonder if the over reading of speed carries over to the odometer etc

Yes it does. My T4 under reads by 5% and it's very noticeable when Waze says 100 miles for a journey and the trip only gets to 95.

Not many people take this into account when working out fuel economy. Some Speedo's over read close to 10% which makes a considerable difference when people think they're getting 40mpg and they're actually getting 36 (as an example).

It used to be able to be adjusted using VCDS under consumption correction, but I'm not sure if it's still the same on newer VAG models.

 

[SteveGSXR600K1]

I wonder if the over reading of speed carries over to the odometer etc

My dash cam shows MPH from GPS data, so very accurate. Always a few MPH below what the car shows on the dash.

Sent from my SM-S918B using Tapatalk

 

[Tonythepony]

Obviously there is a sensor that could be faulty on the stop start system . I had one go and the stop start system wouldnt work as the sensor couldnt pick up when the car was stopped and trigger the stop start but I think there may have been a stop start error message on the msd ?

 

[RUM4MO]

Obviously there is a sensor that could be faulty on the stop start system . I had one go and the stop start system wouldnt work as the sensor couldnt pick up when the car was stopped and trigger the stop start but I think there may have been a stop start error message on the msd ?

Are you sure about that, remember there are certain conditions that need to be met before auto stop/start will get enabled.
For instance, I currently find, in warmer weather at least, if I drive my wife's 2015 VW Polo in "granny mode" it will end up with seriously good MPG figures, but will not have auto stop/start enabled at the first few stops after a 10 mile eco drive in open traffic, the reason for that, from viewing the charging voltage, is that the battery has been getting "bled" of charge to save using the alternator, and so at the first few stops at traffic lights, the engine stays running to charge the battery back up. On the other hand, when driving it in a bit more spirited manner, over the same journey and traffic conditions, the battery is getting well charged so auto stop/start is always enabled after that 10 mile run in open traffic.

If you are having trouble, maybe consider buying in via ebay, a cheap plug in 12V DVM and keep an eye on the displayed voltage under differing conditions, and maybe vary your driving "pattern" to see if you can influence the battery charging. Doing this will also allow you to see when or under which driving conditions either reduces battery charging or increases it.