Any electron wranglers able to think out a simple circuit ?

[MysterG]

Yeah, the golf does that too. That's the sensor I mentioned about disconnecting a few posts up above. The tweak to the ECU code I mentioned actually changes the parameters for the stop start to be active. It raises the minimum acceptable voltage up to a point above what the battery can put out. Trouble is that this means it's totally disabled unless you get the ECU RE reprogrammed again, and as far as I know, it seen as emissions control tampering, and is subsequently an MOT failure.

But it can't be the same as the Fiesta. During all the lockdowns we hardly used the car and due to that the battery was low and the stop start did not active for months. It was only after a hundred miles or so journey it started working again.
If yours is flatting the battery surely something must be at fault?

We've been back to short journeys for months and again it does not stop/start..

 

[daleyd]

We had an Alfa giulietta for about 18 months and the stop/start never worked in all that time, apart from once…no idea what would happen for MOT as I can’t imagine it would ever actually work for them to test

 

[Domdom]

If it's a VW based car as I think I read above, as long as it's not a Lambo or Phaeton it can be disabled with VCDS. I just set one of the parameters (battery voltage) to a high value. Never cuts out at a junction now.

 

[Reman]

But it can't be the same as the Fiesta. During all the lockdowns we hardly used the car and due to that the battery was low and the stop start did not active for months. It was only after a hundred miles or so journey it started working again.
If yours is flatting the battery surely something must be at fault?

We've been back to short journeys for months and again it does not stop/start..

I sometimes go weeks at a time without using the car, but most of it's control units are still busy crunching pointless data and sucking in power even when the cars parked*. Then when I go anywhere it's usually to do a 4 mile round trip to go to Lidl's for my shopping, then Tesco for the few bits Lidl doesn't stock. So I start the car, get to the end of the road, and the stop start kicks in. I disable it, the car restarts and go to Lidl. Then I start the car at Lidl, stop to the carpark exit, and the system stalls the car again. Disable it and carry on to Tesco. Then it's the same thing again as I leave Tesco's carpark. So during this typical 4 mile trip the starter guzzles power 6 times rather than the 3 it actually NEEDS to do. It's those 3 unnecessary restarts I want to stop happening.

(* There's a brilliant comedian who actually mentions this exact problem in one of his shows. REALLY funny guy called David Crowe. Worth a watch if you've got an hour to kill......

).

We had an Alfa giulietta for about 18 months and the stop/start never worked in all that time, apart from once…no idea what would happen for MOT as I can’t imagine it would ever actually work for them to test

An Alfa with an electrical quirk? Surely not. The electrical systems on Italian cars are usually so reliable.

If it's a VW based car as I think I read above, as long as it's not a Lambo or Phaeton it can be disabled with VCDS. I just set one of the parameters (battery voltage) to a high value. Never cuts out at a junction now.

Yeah, but tweaking the voltage parameters also prevents you from turning it on when it could actually be useful. If on a long trip and stuck in a propper stop start traffic jam (Usually because some clueless so and so has spread their caravan over two and a half lanes of motorway 10 miles ahead) having it automatically do the engine stop/start thing might help save some fuel during those 10 minute periods where you're just sitting stationary, between the infrequent 5 car length of progress you actually make on your trip, but stop/start kicking in just because I've momentarily come to a full stop at a T junction just winds me up.

All I'm trying to do is change the default state of the system from on to off, but without the inconvenience of completely disabling the system and having to plug a sensor back in or get a code string changed back on those rare occasions when I might WANT the system on.

Yes, I could use a post-it note on the steering wheel to prompt me to disable it every time I've started the car, but why should I force myself into learning to automatically turn something off whenever I get in the car?

 

[rtcosic]

There is something badly wrong there.

These systems monitor all sorts of parameters to enable the Stop-Start.

Battery state of charge is the highest level one. Stop-Start should not be enabled in the circumstances you describe.

Does it 'disable' the stop-start when the aircon is running? All the ones I am familiar with do this - or shut down the aircon compressor if the 'economy' mode is selected instead.

Does it disable the stop-Start when the Defrost setting is activated? The extra load of the screen heaters, fans and aircon should trigger disabling the Stop-Start.

 

[blackolive (Ste)]

I think with all the devices suggested it would just be easier to press the supplied button that switches the auto stop/start off

 

[8ob]

A glow plug timer relay like the basic landrover unit could be used to power up a normally closed relay.

Bob

 

[Reman]

There is something badly wrong there.

These systems monitor all sorts of parameters to enable the Stop-Start.

Battery state of charge is the highest level one. Stop-Start should not be enabled in the circumstances you describe.

Does it 'disable' the stop-start when the aircon is running? All the ones I am familiar with do this - or shut down the aircon compressor if the 'economy' mode is selected instead.

Does it disable the stop-Start when the Defrost setting is activated? The extra load of the screen heaters, fans and aircon should trigger disabling the Stop-Start.

No, the stop/start system works exactly as VW intended, It's just that it's not how I want it to work.

I hardly ever do over 3 miles on any leg of a trip, so that isn't even long enough to replace the power used by the first engine start of the day. With these short trips and the car not getting chance to charge the battery back up, it means each time I use the car it ends up with the battery a little flatter than it started. Because of this I already have to pop my car's battery onto the charger for it to keep up. The thing is, these extra restarts are eating into how long I can go between having to pop my battery on the charger. If I went on a 4 mile drive into town without disabling the system it would easily do 10 restarts each way, and that would mean I'd only get significantly less time between charges that I COULD if the system wasn't automatically on.

The system would be fine if I were commuting 20 or so miles a day, but as I don't, I fall way outside of the normal use scenario that VW envisaged when they worked out the parameters for this system (To the extent that I also have to remember to make a special trip to the motorway every few months so the DPF get's chance to do a regen).

I think with all the devices suggested it would just be easier to press the supplied button that switches the auto stop/start off

Well, I might be getting pushed into thinking that way too. My original idea was just a few quids worth of components (some of which I may actually already have in my little electronic parts tool box...... I know there's a couple of spare 555 timer chips in there from a project I did ages ago) and a stub of strip board that I could simply tap into 4 wires that are already right next to each other inside the centre console. Maybe adding a hidden latching switch under the edge of the gearstick gator so I could disconnect the system if I needed to, but nothing more complex than that.

A glow plug timer relay like the basic landrover unit could be used to power up a normally closed relay.

Now there's an idea that didn't even occur to me. I'll have to have a little prod about online to see how they work.

 

[Gareth J]

Thinking about it in a different way, could you just fit a voltage reducer that switches in via a toggle switch, so you essentially have and on/off for the system?

Or maybe it'd be fine with no voltage reducer and just cut the power to the stop start's voltage sniffer line with a switch. Although I suspect that might result in an error...


...edit, I see this has already been suggested!

 

[Morris]

Doesn't sound right to me. As rtcosic said there are many circumstances that disable the stop start function. Aren't modern alternators "intelligent" as well to cover the extra loads.
Wifey has a 2019 Suzuki swift sport and does mostly short journeys, never had any issues. The stop start is disabled automatically for a number of conditions and can also be disabled with a button (never bothered).

 

[MysterG]

No, the stop/start system works exactly as VW intended, It's just that it's not how I want it to work.

So it is intended for the stop/start to continue to work even if the battery is low? That makes no sense

 

[Domdom]

All I'm trying to do is change the default state of the system from on to off, but without the inconvenience of completely disabling the system and having to plug a sensor back in or get a code string changed back on those rare occasions when I might WANT the system on.

Do a search on Ross Tech forums to see if the default state can be changed. Has to be better than messing with hardware.

As for wanting it on in rare circumstances, well you do have the start button/key. Stop and Start will also be affected by Air-Con, electrical load, outside temp, and a number of other things. Rarely (if ever) would you see SS turn off the engine for more than a couple of minutes.

Also, the SS function does not operate if battery voltage is low. Your concerns about short trips are taken care of by the battery charge and monitoring module. I understand that SS can be irritating (hence why I disabled it) but the electronics know more about the battery state of charge than you do. Loads of R&D cash versus an opinion basically.

EDIT: Just to add that the charge module also holds details on the battery type, date installed, serial number and capacity in AH. It does have a curve where it adjusts things to compensate for battery aging, loss of capacity etc and this is why a new battery has to be "coded". In fact, the important part is changing the serial number since this is what tells the charge module that a new battery has been fitted. 100% necessary? No, but it is what performs the reset to get back to optimal charging for a new battery. My point is that this charge module is a lot more intelligent than might first appear to be the case.

 

[skotl]

How about introducing a 555 into the circuit?

Something along the lines of:

Generating a delayed pulse of 0,5sec with one 555 timer upon powering up the circuit

In the link below, this circuit I found is what I needed. Only the length of the pulse and the delay are not what I want. When I want just 0.5sec before pin 3 is up and the pulse duration I want i...

electronics.stackexchange.com

That was my thought.

Also, if you can't be faffed doing it yourself have a look at the Carista capabilities for your car: https://caristaapp.com/vehicles

I paid £15 on Amazon for the device which comes with a free month subscription - bought it only to disable the stop/start functionality on my car and it was worth every penny.

 

[500e]

It can be dangerous with the delay coming out of junctions.
Neww skodas have no button

 

[Reman]

So it is intended for the stop/start to continue to work even if the battery is low? That makes no sense

No, as I said, it works as intended. The stop/start systems turns off when the battery is getting flat, but the problem is that by the time the system disables stop/start the battery's only got enough power for a handful of restarts left in it anyway, so by the time that kicks in it's already at the point where I'd need to put the car on charge anyway.

Do a search on Ross Tech forums to see if the default state can be changed.

I looked into the VCDS and Carly systems, and both kill the stop/start by raising the minimum voltage that the system needs available for it to activate. Generally it makes the system think the batteries too flat to risk enabling stop/start, and that prevented it from working even if you do wanted it on. You also get an annoyingly bright permanent warning light on your dash (Same as if you disconnect the sensor on the batteries positive lead). At least with my idea I could turn the system back on using the original button if that light became a distraction at night.

if you can't be faffed doing it yourself have a look at the Carista capabilities for your car: https://caristaapp.com/vehicles

I looked at the Carista one, but was too put off by the idea of a monthly subscription to bother looking into it any further. I decided that I'd use it so infrequently that I'd end up having to pay a tenner for a months subscription every time I wanted to tinker with something. I don't know how that one disables the system, What car do you have, and can you still turn the system on if you want?


Oh, and just to pre-empt the next question, No, the battery's fine. The original gave up about a month ago, so I fitted a brand new one then. It's also the correct spec of Lucas AGM battery for this specific model of stopy/starty bluemotion Golf, so we don't have to go down that road either. ......... The car's currently working 100% as VW intended.

 

[voipio]

I just turn stop/start off when starting the car. It's not really that much faff. I know others do the same.

 

[daleyd]

I just turn stop/start off when starting the car. It's not really that much faff. I know others do the same.

That's what I generally do, the button is quite accessible in mine (BMW) - and even if it's been on for a journey I always end up tuning it off just before I get home as there is a road just up from my house with bad visibility (But very quiet so very little traffic). You have to stop but are generally setting off again straight away, if I don't turn it off it cuts out for a sec then is started again

 

[skotl]

...

I looked at the Carista one, but was too put off by the idea of a monthly subscription to bother looking into it any further. I decided that I'd use it so infrequently that I'd end up having to pay a tenner for a months subscription every time I wanted to tinker with something. I don't know how that one disables the system, What car do you have, and can you still turn the system on if you want?

...

Yeah, but it was literally the £15 one-off. Used the free month subscription and didn't renew.

It's an Audi and the feature I enabled was "remember state of start/stop when ignition is restarted" so that means I turned off start/stop once and have never had to touch it again. It stays off whenever I restart the car.
That does mean that if I went mad and decided I did want it enabled then I just need to press the switch once and it will remember it.

 

[skotl]

More info from Carista: https://blog.caristaapp.com/disabling-start-stop-systems-199150b6356c

 

[Domdom]

You also get an annoyingly bright permanent warning light on your dash

Not on my 2014 Skoda Superb you don't. Nor my mate's Passat that I did.