Battery problems

KrisS3 · 29 Nov 2009

Hi all,

Well I know its been done to death but has anyone a definitive answer as to what drains the battery when the car is not in use??

Mines a 06 C2 and had a new OPC battery about 2 months ago. I mainly use it at the weekends but had to use my other car last weekend so basically 2 weeks and the battery was totally dead! I've now bought a battery optimizer to keep it topped up but seems a pain which I've never had with other cars standing or even motorbikes for 6 months.

All I can think of is alarm and tracker being active when parked up?

Your thoughts appreciated gents .........

Porsche · 29 Nov 2009

after 7 days the car should go into a stand by mode to prevent excessive battery drain which is what is on the 996 gen cars

if this isn't happening then you're going to have issues, maybe worth doing an amp test but what you describe should not happen unless you're not using car enough at weekend to charge the battery :?:

wizard993 · 29 Nov 2009

You should get more than two weeks from a new battery!

1) maybe it only had a 60% charge when it was fitted hence the short timescale.

or

2) It's knackered(not as uncommon as you may think, re a new battery), especially one that's been sitting around a while

Give it a good 24 hours on a slow 4-amp charge and see how you get on.

If it's flat after two weeks again, get it tested as it's probably a dead/faulty cell.

theogeor · 29 Nov 2009

One other thing that is worth checking is the alternator. If its not charging the battery properly then you will think that is the battery that is gone. Maybe the battery you have is still fine.

Theo

KrisS3 · 30 Nov 2009

Thanks guys. I've put the battery on the new fandago charger which is going through various modes of slow charge. The charger displays amps/volts and battery percentage charge held so if all is not well then it goes back to OPC for a replacement battery or (fingers crossed not) get the altenator tested.

whaletail · 30 Nov 2009

2 weeks? Luxury! regular viewers will know mine lasts less than 5 hours between a full charge and death. :sad:

andym · 1 Dec 2009

It could be the power cable which runs from the alternator to the starter motor. Check the output at the alternator and then at the battery with the car running, should be just over 14V, if it is less at the battery then it could be the cable.

There is a known issue with the connectors degrading over time causing resistance and voltage drop. So essentially the battery is not being charged properly. Another symptom is hard starting when the car is hot.

The cable is about £90 from Porsche and fitting should take around 3 hours although they have a book time of 6 hours on that job.

cheers

Andy

Ocean Blue · 2 Dec 2009

Battery

Kris,
Did you check that the Battery posts and lead connection faces where clean and that they had been sealed with a proprietary grease. If the lead has oxidised it can be difficult for the alternator to push a current through the battery. I've experienced a new battery where it was just slapped in and experienced the same symtoms as yourself.

whaletail · 2 Dec 2009

andym said:
It could be the power cable which runs from the alternator to the starter motor. Check the output at the alternator and then at the battery with the car running, should be just over 14V, if it is less at the battery then it could be the cable.

There is a known issue with the connectors degrading over time causing resistance and voltage drop. So essentially the battery is not being charged properly. Another symptom is hard starting when the car is hot.

The cable is about £90 from Porsche and fitting should take around 3 hours although they have a book time of 6 hours on that job.

cheers

Andy

Will this still apply even if the voltmeter on the dash shows 14v and charging?

I had a plan to disconnect the alternator and leave the car in my garage for 2 days to see if the battery still drained flat. My plan was scuppered by the fact that I can barely see the alternator, let alone touch it! :frustrated:

andym · 2 Dec 2009

whaletail said:
Will this still apply even if the voltmeter on the dash shows 14v and charging?

Not sure, easy to check it at the battery though with the car running, this is key to seeing the voltage at that end of the car, and not just the alternator output.

If it is 14-14.2V at the battery then it is likely something else and not the cable.

Just to clarify, the cable issue is a known fault on early 997's but the part number has not changed so there will be a more occurances as the cars get older.

KrisS3 · 2 Dec 2009

Thanks for the feedback guys. The battery is now recharged and the charger is showing battery at 100%. I'm going to check the battery over the next few days to see if there is any power drop when not in use. Terminal connections look ok but I'll double check them. After that touch wood I'll see how it goes and hope it's not alternator or lead.

whaletail · 6 Dec 2009

Have a feel of the alternator on a cold morning before you start the car. If it's warmer than the surrounding engine bits, the alternator regulator could be sucking the power from the battery and turning it into heat.

My car is going in for a new alternator on tuesday so I'l let you know if this fixes my problem. Or if I forget, check the 996 forum!

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