Stop / Start and battery condition

[PHB1969]

So.....I bought my 2.5 f4t GTS new last August.
Set it up on ctek charger exactly the same way as my previous base cayman (Using agm mode and same earth points).
The base cayman always used to switch straight into stop start mode when I reached my drive end or first junction. The GTS doesn’t. To be fair, it’s not being used much, but on trickle I thought it would be perfectly topped up. For example, today I did c 35 miles, the last on the motorway and it didn’t drop to coast mode and never dropped to stop start Even when I returned home.

On other drives, it has worked fine, but after 20+ miles

Note - not in sport / sport+nor disabled by the centre button.

Any thoughts what might be causing this?

 

[JohnCRS]

I would understand variations in when stop/start was activated due to engine temperatures and other sensors, but this does not stack up with it not operating after 20+ miles. My first thought was confusion over whether it was off or on when the indicator light on the button was showing. This certainly has caused confusion with aircon. (Forgive me, I am not questioning your intelligence but I have certainly had to resort to the handbook on occasions)

I don't see how the connections you made with the charger would have any effect, assumin the charger itself is disconnected when in use. It would be interesting to hear from others, especially those with the same model as yourself.

 

[Motorhead]

Paul,

I wouldn’t think that your GTS should be any different from your previous Cayman, especially if it was also a 718, so what you’re describing doesn’t sound right.

The car’s under warranty so I’d get it booked in for a diagnostic check and any necessary remedial action.

Jeff

 

[PHB1969]

Thank you both.

Stop Start is definitively enabled as on some drives it kicks in eventually

I will call Teeside OPC regarding diagnostics - with relaxing restrictions does any know if OPCs are giving loan cars yet?

 

[Philip Morris]

Paul, Yes they are. I also use Porsche Teesside, my car was in for a small issue under warranty in May and I was given a courtesy car for a couple of days - FOC

it is going in a few weeks time, for first service of which I’ll get a courtesy car - but now have to pay £25, I believe this is the new policy!

I’m sure they will sort it out,

Phil

 

[911hillclimber]

Sorry if this turns out to be a red herring, but the start stop faltered and then ceased to work on my daily Skoda.

It was the battery failing, new one fixed it.

The car senses a failing battery and disables the function to save load on the battery.

 

[PHB1969]

Just spoken to Teesside - checked the obvious stop / start conditions sport / sport plus etc. Mentioned a couple of others which I wasn’t aware of - fuel level (car was full), greater than a 7 degree difference in internal to external temperature (Didn’t check if that was C or F). Cabin was set at 18, external was definitely not higher than 25.

He said there was a large range of additional parameters (note last trip was 33.2 miles and didn’t work at all). Car booked in for 27/08....earliest time for a courtesy car!

i will monitor and will try setting the internal temp to match the external temp to rule that in / out.

 

[Motorhead]

That’s a strong possibility Graham, although Paul says that he’s had the car on a battery conditioner and that stop/start seems to be intermittent even during and after a run when the battery should be fully charged.

Having said that, modern cars with their complex electronic systems seem to be particularly sensitive to battery condition, so it’s always a good first port of call when problems arise. Although it’s a new car, perhaps it was sitting in the showroom - or worse, in the compound - for a while pre-sale without a battery conditioner … plenty of time for battery problems to build-up.

Jeff

 

[PHB1969]

The ctek shows light 7 and then goes to 8 after a period of time (understand that is 10 days) So assume it’s fully charged and ok. Is also set on AGM mode.

OPC did say that if the system fails, you should get a warning message.....so they think it may be one of the multitude of parameters that hasn’t been met, which seems strange given I had no operating queries with the base 718 Cayman previously (albeit 2.0 vs 2.5). Hmmm.

 

[Motorhead]

Battery-wise that all sounds good Paul, so maybe the problem lies elsewhere. Maybe you can get the dealer to swap-out the battery as a precautionary measure?

At least it’s not a driving-critical problem, so you can continue driving as normal and get it check-out as and when.

Jeff

 

[911hillclimber]

Swop out is the best approach, nothing else to consider if it fixes it all.

on my Skoda, the car was delivered in mid 2014 and I had this issue 6.5 years later, original battery.

cold starting in winter was getting sluggish, but always started, it is a diesel, so works hard!

Hope you will report back on all the findings so We learn from this.

 

[PHB1969]

Read an interesting post on another forum - suggesting key fob battery based on their own experience:

If the fob battery is low, the KESSY system has trouble confirming that the key is in the vehicle. For anti-thieft reasons, the vehicle is not permitted to start with out confirming the hash or passkey code from the RFID chip, in the key fob; thus the engine is not permitted to auto-start after shutdown.

I‘ve just placed a prime order for a CR2032 and will give that a shot.

 

[911hillclimber]

That's interesting, during my Skoda sort out I too changed the fob battery as that was getting erratic, did nothing, but was another function that was weakening.

hope that fixes it, but was all fixed changing the atm battery in one fell swoop!

 

[Motorhead]

Paul,

You should have been given a spare key when you purchased the car. Why not try that first to see if it cures your problem?

Jeff

 

[PHB1969]

Thank you - Very good point - sometimes cant see the wood for the trees!

 

[911hillclimber]

Sorry, no.

I assure you it is only me who suffered from that syndrome![]

 

[PHB1969]

So - tried 2nd key and battery swap in the original key. No difference. Went out and after 38 miles, coast worked but no stop start working. Changed multi function display to show battery when car is running show 14.4v and sometimes 14.5v which I understand is normal. When engine off and ignition on battery starts at 12.5v and drops to 12.1v over a period of about 30 seconds

Does that sound like the battery?

I’ve been trying to speak to Teesside all week - I think they have some staff off, want to understand if they can do diagnostics whilst I wait, rather than having to wait to end of August for a courtesy car.

....and assuming it’s battery 3 things, why does my CTEK appear to be reporting everything as ok? Is the battery covered under warranty (assume it is)? Are they likely to suggest that having it on a CTEK has caused the problem?

Thank you

 

[911hillclimber]

Just my 2p:

As you are dealing or trying to deal with an OPC, I would simply approach them with the faults you have noted, and ask if they will do a check while you wait to confirm or otherwise the issue.

I would leave everything else out of the conversation.

 

[PHB1969]

Update on this - car on CTEK MXS 5.0.

Connected to positive terminal and the negative to the bolt that holds the battery securing strap (at the front of the battery).

CTEK runs through full charge and maintain cycle - did a video of it this morning with light 8 on solid (as it has been on for more than 10 days).

Drove to OPC - 40 miles no stop / start no "coast" mode.

Just received the health check video - in which they tell me the battery was only 63% charged which is why the stop start isn't working.

They also told me the CTEK doesn't charge the battery it just maintains it at the last charge rate it was at when the vehicle was turned off.....is that true?? The manual says it is a "charger".

The way the unit is connected recognises the issue of not connecting to the negative terminal.

They have said they wont change the battery as it is not at fault - all I can think is:

- CTEK duff? Although worked 100% on the previous Cayman.

- Battery duff and loses charge at such a rate that when the operating temps etc are met, it is below the 80% charge rate that is required to allow the stop / start to work.

I've asked them to go and check the battery again as if there is a problem with catastrophic charge loss then I would expect it would manifest.

They have suggested bring it back if it continues - I've told them no, that they need to investigate.

In the meantime, I will also check out the returns process for the CTEK to hopefully eliminate that if they wont do anything else.

Any thoughts??

 

[BrianJ]

The only thing I can think of is that the battery is defective and won't accept 100% charge. A bit like a phone battery deteriorates over time to say 60% original capacity. You can charge it up as far as it will go (ie "fully charged") but under those circumstances it is still only 60% of original capacity. An iPhone will tell you it is fully charged but if you look at the battery charcteristics data it will also tell you it is only achieving 60% of original capacity. If the car battery is behaving like this, the CTEK will charge it up as far as possible, but the car's stop/start etc will know it is only at 63% (or whatever) and won't activate. So to me, it sounds more like a defective battery than anything else, presumably still under warranty as the car was new last August. I've used a CTEK MXS 5.0 on current 981 and previous 987 for years without any problems like this.