Robuk

It would be interesting if someone could actually post how the Porsche system works, similar to this below for Hyundai.

Attached is A PDF from Hyundai UK explaining about the AMS system. The text from this pasted below.
This model has an engine ECU controlled alternator and this is designed only to operate in a way that reduces fuel consumption and emissions. So effectively it will actually do very little unless it really needs to, which means that until it detects an electrical load from things such as headlamps, HRW etc it will do the bare minimum to charge the battery up. If the customer is only doing those sorts of short journeys and not using any electrical items then the starting of the engine has taken charge out of the battery, but without any electrical items being used it won’t put that much back into the battery again. The Alternator Management System (smart charge) works in a very different way to a conventional alternator. The conventional alternator is charging at all times whenever the engine is running, and will increase its output back to the battery depending upon electrical load and the speed it is being rotated at. In the AMS system the charging function of the alternator is controlled electronically by the engine control ECU based upon various sensor inputs and how the vehicle is being driven, so it can be that the alternator will not be charging the battery at all dependent upon the circumstances at that time. Effectively as the alternator is controlled via the ECU it will only charge the battery when necessary, this is to reduce emissions and improve fuel economy. In certain conditions the system will only charge the battery in small amounts.
So if the vehicle is only used for short journeys, and as the system often does not charge at all after a cold start, if you are only doing low mileage the starting of the engine can take more charge out of the battery than the system will put back in again.

Strassenkurven

Is everyone here talking about the 971?
My 970.2 has kept the auto stop/start button lit up for the two weeks I've had the car. I don't know what a previous owner did, but it definitely remembers my last setting between drives.

DogWood

yeah "not staying off" thing is a 971 issue, for 970 drivers the off button keeps it off.

Robuk

Have you actually tried switching it on, if it is staying off it could be a low battery.

user 8298308

My 2016 4S definitely doesn't keep start/stop in "off" mode between drives. Always reverts back to On.

Robuk

If your car has one of these attached to the ground lead of the starter battery just disconnect the small black plug, stop/start will now be deactivated.

KINGSRULE

It changed in 2016 to always on......

KINGSRULE

Does this apply to 971?

Robuk

As the 970 has stop start I presume the 971 will have, just check to see if a similar sensor is attached to the starter battery ground cable, this sensor in pic looks exactly the same as my Merc`s.
Disconnecting is same as if sensor failed, it should not throw a CEL, if you decide to try it smart charge will revert to standard charge with no regeneration. For piece of mind purchase one of these, https://www.ebay.co.uk/itm/New-LCD-C...-/282137850944 . Then drive car for a day and note down the varying charging voltages, probably be from 12.5 (no charging) to 15-16 (regeneration). Unplug sensor and charging voltage should then be no lower than 13.6/8 volts (float charge) to 14.4/6 ( actual charging battery voltage), this can vary slightly, my Merc`s are float 13.8 to 14.2 charging volts. Drive car for a while and watch voltage. The Merc`s have had no issues over the 8 months I have been driving with this disconnect. As said it is no different to the sensor failing, if you have any issues just reconnect the sensor.

Strassenkurven

yes.. it keeps the setting that I've left it at. Mine is a 2014.

Robuk

Perhaps your year model had this choice and later models don`t, would be interesting to compare with other owners of same model year, things can change in same year though.If that is not the case then it may be helpful to others if you could contact previous owner.

B Russ

Is there any reason NOT to be in sport mode All the time?

Robuk

Well in sports mode the auto gearbox hangs onto the gears longer, so I suppose to get better MPG you might just slip it in economy if you are say driving a longish distance at a restricted speed limit, 50 MPH here in the UK, other than that NO. Does stop start go to OFF in sport mode.

B Russ

I believe Auto stop is disabled in Sport mode

krabman

Defaulting to start/stop on is not required in sport, sport+, and individual, because the car was not certified with the EPA in those modes, it was certified in normal and with start/stop on which means it must always default to start/stop on and in the normal mode at start-up. I've already explained why this is in my previous posts so some of you may want to read those so you understand what's going on.