Porsche Start Stop

[7and911]

Never had a car with start/stop. Awaiting delivery of 991. Any one of you gents had a view about the effect of start/stop on the battery and/or the starter. It wouldn't be good to save a few pounds a year on petrol then pay a fortune on a new battery of a starter...

Thanks

[IPK]

It just makes me drive in Sport all of the time!

[Ady128]

Well, Porsche must have tested this to destruction and apparently according to James May it does save fuel. You'll get used to it.

[Bennachie]

No you won't. Just get used to switching it off with your left hand as you twist the starter with your right.

I hate it.

I am old. When I drive my car 100 metres down the road and it stops running at the traffic lights, it is broken........

[7and911]

will pressing the button also cancels coasting?

[mr pg]

Ady128 said:

Well, Porsche must have tested this to destruction and apparently according to James May it does save fuel. You'll get used to it.

Looks like Porsche have left testing GT3's to destruction to owners!

[paul0843]

Would not buy a car without it.
Agreed takes a bit of getting used to at the beginning
but eventually when in traffic u don't even notice..
Consumption improves dramatically and when u fancy a bit of fun u turn it off..

[7and911]

Question remains... Will it affect the life of the battery and starter?

[anonymous-user]

7and911 said:

Question remains... Will it affect the life of the battery and starter?

It must do if you think about it as both items are going to get more use. Also Porsche are going to make more money replacing them. Win-win on their side. I'm not at all convinced it's a good idea for the owner.

[truck71]

Bennachie said:

No you won't. Just get used to switching it off with your left hand as you twist the starter with your right.

I hate it.

I am old. When I drive my car 100 metres down the road and it stops running at the traffic lights, it is broken........

This, total pita. No doubt effective but bloody annoying.

[Pope]

It can be coded default ON / OFF or LAST MODE - just ask at your OPC for them to do it as you like it (has to be done on the tester)

BTW the battery is an AGM type not trad Lead/Acid - designed for Start/Stop type demands and the Starter is a stronger design (it just sounds like it starts easier - like a small person sneezing in the boot!)

Also the DME and the sensors attached know which cylinder the engine stopped on so it can fire up quicker (no longer has to turn over twice to find tdc no.1 before initiating ignition/injection)

[Matt Seabrook]

A lead acid battery has about 40-50,000 start cycles for a good quality battery. An AGM should be good for 360,000 starts and can deep cycle better than a lead acid battery. As Pope has said the spark can be fired on the cylinder that was due to fire and almost wouldn't need assistance from the starter motor. So don't worry to much about the battery

[m3evo321]

I had not even heard of AGM batteries... AS we are all aware the 'normal' battery in a conventional Porsche is best kept on a trickle charger to stay in tip top condition if the car is not used on a regular basis.
Therefore is there an advantage to us all if we started using AGM batteries??????

[Pope]

http://batteryuniversity.com/learn/article/absorbe...

The power of the internet......

[ORD]

I doubt it has been tested for long term effects on the engine. Does it operate even before the oil is up to temperature? I bet it does, which is bound to make it on balance a bad thing (except for stupid mpg figured that mean f all in an 80k car).

[Matt Seabrook]

m3evo321 said:

I had not even heard of AGM batteries... AS we are all aware the 'normal' battery in a conventional Porsche is best kept on a trickle charger to stay in tip top condition if the car is not used on a regular basis.
Therefore is there an advantage to us all if we started using AGM batteries??????

You have to be careful with AGM batteries as you can't use a regular battery charger to charge them. If you do you can drastically shorten the life of the battery. One of my BSU (Battery support unit) needs to be set on AGM the other does it automatically. These "battery chargers" have a saw tooth programme to charge the battery so as not to knacker them by over heating the battery. I must be honest I'm not sure if the maintenance charges a lot of us use would be any good for an AGM battery. I would say if the car is put away for three or four weeks then there would be no need with an AGM battery to keep it topped up as they are quite a lot more powerful.

Edited by Matt Seabrook on Sunday 23 February 20:41

[mhh]

How common is the re-coding? I had this done on my M5 but my OPC said it isn't possible...

[sidicks]

ORD said:

I doubt it has been tested for long term effects on the engine. Does it operate even before the oil is up to temperature? I bet it does, which is bound to make it on balance a bad thing (except for stupid mpg figured that mean f all in an 80k car).

As with most of these set-ups from other manufacturers, it is only active if the engine is already up to temperature.

[truck71]

Unfortunately in porsche' s system it activates from cold.

[sidicks]

truck71 said:

Unfortunately in porsche' s system it activates from cold.

"The auto start/stop function may remain inactive under particular circumstances, for example: extreme outside temperatures, when the SPORT button is selected or if battery charge is low."