Battery Conundrum

Stevie996 · Apr 2, 2012

I think I have a similar problem with my 2009 987 gen 2.

My local OPC disconnected my battery recently and did some recoding. Since then my interior lights stay on for over 3 minutes when the key is removed. If I lock the car they go out. The handbook says they should stay on for 30 seconds.

It's back to the OPC tomorrow for them to sort out.

Could it be the battery?

Steve

Buddy · Apr 2, 2012

I changed the battery on my car last May and fitted a Moll due to having the extended warranty, took the battery home from the OPC and charged it to max, before fitting no problems with lights etc.

And I'm currently using a trickle charger, the old battery is connected to a second charger to see if it will be ok for reuse as per Ctek claims and it does charge in a short time but I've not had reason to refit to the car.

I've not previously heard of anyone having such problems when changing to the Bosch Batteries either.

Richard_Hamilton · Apr 2, 2012

And why would they "protect" a 3.4 and not the 2.7? Seems nonsensical to me, but so does the problem!

Steve Brookes · Apr 2, 2012

ORIGINAL: Richard Hamilton

And why would they "protect" a 3.4 and not the 2.7? Seems nonsensical to me, but so does the problem!

I didn't mean it like that. I meant when the S model was changed from the 3.2 to the 3.4, that a change 'might' have been introduced. But you're right, none of this is making sense. All I can establish is that everything works as it should with Moll but not with three other batteries (2 x Bosch and one non branded motorfactor type battery). The Moll is by far the oldest of them all and struggles to turn the engine over. Hence I can't relie on it.

If buying a Moll from the OPC would be guaranteed to fix the problem, I would do it but at the moment I'm not sure it will! The easy answer would be to pop into my OPC and ask them to fix my interior light problem. However, they'd probably say; "we found the problem sir, you didn't have a Porsche battery in so we've put one in for you" but wouldn't mention the bit of secret coding that they did at the same time when they swapped it. [

]

Steve Brookes · Apr 3, 2012

ORIGINAL: whhuer

There is an additional wire to the negative terminal, as per the photo which hopefully has uploaded.
My thinking is that as there are a number of items which control these lights, ie door switch, door locking, ignition and manual switch, with a delay if the car is not locked, then an electronic circuit will control the operation, possibly via a solid state relay. With a good fully charged battery the voltage with the engine running the battery voltage will be about 14v but if the battery is on its way out then the voltage will be lower. If one of the electronic components is sub-standard then this could cause the problem you are encountering. Hopefully any such electronic circuits will not be part of another module, i.e. the ECU.

Regards
Wolfgang

Thanks Wolfgang, the wiring on mine looks the same. I'll check voltage outputs with the engine running for the Moll battery and then with the S5. It'll give me something to do at the weekend.

However, if the problem is associated to the state of the battery I would expect the interior light problem to be with the Moll and not the S5 because the Moll is the older battery, is on its was out (struggles to turn over the engine) and it's generally regarded to be a poorer battery than the equivalent Bosch Silver.

rich mich · Apr 3, 2012

i think the next step you should do is try another moll battery off another boxster and see if the problem goes away (can anyone with a 987 s swap their battery just to see what happens). i changed my moll battery on my 987 last year,to a bosch and had no problems with it .i work in vechicle electrics (21 years at ford ,jag,volvo and landrover ,engine dyno testing) all this talk of coded batterys is nonsense, (a battery is a device to store energy the only thing i can think of is if the lights are can bus controlled it might be corrupting the module somehow.

Motorhead · Apr 3, 2012

A rather obvious question Steve but have you spoken to your local OPC?

a) They might have experienced the problem themselves or have some suggestions.

b) They might let you try out a "spare" MOLL battery if you take the car in and/or let you have sight of the circuit diagram.

As Wolfgang and Richard have suggested, it's got to be related to a voltage-sensitive malfunctioning component.

Whatever, it's made an interesting post..!

Jeff

Richard_Hamilton · Apr 3, 2012

Steve - I hope I didn't sound confrontational. It is just that the 987 2.7 uses the same control units as the 987 3.4, so if there was some way of programming a unit to recognise a security device in a battery, then you would have thought they would programme all models the same. You would also have thought that they would make the effect of fitting a non-Porsche battery more severe, like refusal to start, perhaps. I just can't see that Porsche would do such a thing, especially considering the ructions it would cause in the US.

I have no idea what is wrong, but I suspect that the module which controls the interior lights has thrown a wobbly. (Technical term). I wish you were closer to me, as I would happily swap batteries to test, and plug in the tester to see if there are fault codes stored.

Steve Brookes · Apr 4, 2012

I will get hold of a Porsche tech at our local 981 launch in a couple of weeks and get their opinion and then report back.

Buddy · Apr 5, 2012

Some recommend connecting a trickle charger before disconnecting a battery to maintain the memory in the radio etc.

But this is the weirdest battery problem I've ever heard!

On a related item, there is said to be a problem with the starter cable lead on 987's & 997's which overheats due to repeated attempted starts ends up needing replacement which on some cars is an engine out job. Just thought I'd mention it.

Steve Brookes · May 22, 2012

**UPDATE**

After taking some voltage measurements of the Moll and Bosch batteries both on and off the car. With and without the engine running. The problem with the interior light staying on decided to manifest itself with both batteries. Indicating that the times that the Moll 'cured' the problem was merely an aberration. BTW both batteries gave acceptable readings of over 12.6 V with no load, about 12.3 V when in the car and 13.5 V when charging. But the Moll still clearly struggled to crank the engine.

This of course meant that the car had a permanent problem of the interior light staying on (with the doors closed and engine running). So, I took it back to the supplying dealer (not an OPC) who immediately put on a new battery. However, the light problem remained. They then plugged it into their Porsche system tester, did whatever it told them to do, reset the system and now the light is working normally. The battery they put on is some sort of generic 80 amp battery and works fine. They agreed that the 5 year old Moll was just about dead (struggles to crank the car) and think that it was that which caused some of the car's settings to go out of synch. So, now I've got a new battery (free) and properly working interior lights!