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Discussion summary
YOUR RESEARCHBattery Issues Again!
Reported or suspected cause
common
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
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Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
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Reported cause
The horn problem is common, but it won't be draining your battery - you just need a new horn.
Discussions that performed work without a confirmed outcome
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
have just run through removing each fuse one by one with the multimeter measuring current between (disconnected) neg lead and neg terminal on battery with key in accessory position.
Leading evidence: 'common' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'common' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Disconnect ) neg lead and neg terminal' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
have just run through removing each fuse one by one with the multimeter measuring current between (disconnected) neg lead and neg terminal on battery with key in accessory position.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I fitted a Halfords Calcium battery correct for my car as per the little Halfords guide.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I bought my 996 C2 2 weeks ago and replaced the battery on the 3rd day of ownership.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
Kept going flat, had the car tested for power drains etc but nothing, in the end he got another battery, and it was fine.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Disconnect ) neg lead and neg terminal
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
have just run through removing each fuse one by one with the multimeter measuring current between (disconnected) neg lead and neg terminal on battery with key in accessory position.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
The alternator is the next possibility, anyone know how i can easily disconnect the alternator to test the current drain of it and also if there should be any current drain through a healthy alternator?
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Suggestion · Original poster
have just run through removing each fuse one by one with the multimeter measuring current between (disconnected) neg lead and neg terminal on battery with key in accessory position.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
911uk: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T135432Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I know there is a comprehensive thread on flat batteries but I still am not sure what to do...
I bought my 996 C2 2 weeks ago and replaced the battery on the 3rd day of ownership. I fitted a Halfords Calcium battery correct for my car as per the little Halfords guide. This morning the car would not start and had to be jumped.
As far as I know, the only non-standard part on the car is an RAC Trackstar tracker. I have spoken to the authorised fitter who says there is no way the tracker could be draining the battery overnight. The voltmeter on the car shows 13.5-14v in normal driving.
Any ideas greatly appreciated.
Could the new one be a dud battery?
My father had a similar prob with a new battery on a BMW. Kept going flat, had the car tested for power drains etc but nothing, in the end he got another battery, and it was fine.
Not sure what the in-car voltmeter actually shows- I had a flat battery a while back and it was reading fine right up to the point the car wouldnt' start...
Could be a dud battery and the halfords calcium is ok but the one to get is bosch s5 010 or varta f18. the bosch is hard to find but the varta is 85ah and 800cca which is higher than even the porsche battery and half the price! you can get one from
www.manbat.co.uk
there are dealers all over.
I had a mega drain on my battery before. It was because of the the previous owners who had all sorts of gadgetry attached to the battery i.e speed camera finder, hands free kit, hands free aerial woven into the tax disc! plus a clifford alarm on top of the porsche one! dont ask.. and a stereo install that looked like it was done by two year olds! the garage gave me a box that weighed about 7 kilos, which were wiring looms and electrical junk that came out of the car!! good as gold now ;-)
Had a similar problem with my battery, one of the cells had gone. I went for a Varta replacement, it costs more but is much better IMO.
Every thing worked fine for 2 months, then that started going flat. I had it tested and the alternator needed replacing. Its been perfect ever since.
Take the Calcium back to Halfords - ask them to change/test it. No quibble guarantee
Why did you need a new battery anyway? How old was the old one?
Varta/Bosch are the same company, and although good (I've got Varta blue-top and Bosch Silver on other cars) I have a Halfords Calcium on the 993 and it holds charge very well, so as said above, it's either dud (unlikely) or you have a problem....
My favorite one - sit in the car with the doors closed and keys out of the ignition - do the windows operate?
Essentially you need to get a meter on the battery, and disconnect every system (pull the fuses) until you find which one is causing the drain. If it's the alarm of course, you might not be able to do this - any trustworthy 'specialists' nearby?
thanks for the help guys!
I have found the fusebox and when the snow stops I'll do a bit of investigating.
One of the horns does not work and I wonder if this might have some kind of internal short that is sapping battery power?
regards the original battery - when i bought the car it had a small unbranded battery on it despite the service history saying that jz machtech had fitted TWO new Bosch Silver batteries in the last six months for the previous owner! I think the dealer who had the car for 2 weeks in between may have pinched the shiny new Bosch and put a dud in it's place, that's why I changed it.
I have a Halfords trade card so £37 off a £99 battery was too good to turn down. (Thoroughly recommend the Halfords trade card by the way, easy to get and well worth it)
Camtune are not far away but i feel i should be able to do basic diagnostic stuff and save a bit of cash.
if it had two Bosch batteries in six months, I think we can safely say it has a problem
Don't forget the windows, and the lights in bonnet/engine compartment.
Good luck. :thumb:
The horn problem is common, but it won't be draining your battery - you just need a new horn. Your problem is one or a combination of the following;
1. Faulty battery
2. Faulty Alternator
3. Something is draining your battery even when the ignition is switced off.
Regarding point 3, if you charge your battery at the battery terminals over the weekend and the ameter, assuming your charger has one, is still showing current being drawn after 48 hours then you can start to eliminate the problem by pulling fuses until the current drops to zero. the fuse should then lead you to the cause of the problem.
Good luck
Ray
have just run through removing each fuse one by one with the multimeter measuring current between (disconnected) neg lead and neg terminal on battery with key in accessory position. with key in this position and doors open (interior/courtesy lights and dash lights on) I'm getting 7-8 milliamps (if I'm reading the scale right!) of drain. The removal of any fuse doesn't reduce this much...
The alternator is the next possibility, anyone know how i can easily disconnect the alternator to test the current drain of it and also if there should be any current drain through a healthy alternator?
My neighbours are probably really fed up with that damn alarm siren already!!
Ian Howells does have a point, I have seen the alternator draining the battery. Essentially the electronics in the reulator leak current to earth. the alternator regulator will be warm to the touch, in other words the current drain appears as heat. If you have interupted your -ve 12v supply by placing your multimeter in series with the battery and earth then you dont seem to be draining much current through anything, and that includes the alternator. If the car starts by jumping then it could be a faulty starter motor, i.e. the cranking amps are higher than your battery can deliver. I am assuming that the cold cranking amps rating of your battery is within the required specification.
The other thing you could check is to place the ameter in series with the battery again, then locking your car with the remote and then seeing how much current is being drained. It could be that something is draining the battery in this condition only. It's then a case of removing fuses as you did before to locate the problem.
Ray :dont know:
with everything connected as normal and the central locking locked, i am getting a reading of 0.09 amps between the -ve lead and the -ve terminal on the battery, is this excessive?
This could be the point where I give up and send the car to Camtune...
Whatever your final reason works out to be. Get yourself the little trikkle charger that they use on Porsche/Mercedes to keep the battery up while you track the problem down.
Big Bob
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