Dead Battery?

Okay, went to go out in the 996, unlocked fine, everything A-okay during starup ('98 C2)... twisted key, click click click.. Volts showing 10v (rather than 12 i guess), drivers window acted weird, oh, and alarm went off a bit... Pretty sure the battery had lost charge (not sure how or why, car got used loads last week and weekend), but wanted to check with you guys first - does this sound like the battery? I opened the boot while i could - so i can access the battery... Can I just go get a trickle charger from Halfords (nearest Porsche garage is a long way away and I'm busy for the next few days), and if so, what spec do I need?

You want to get a 'batter conditioner', not just a trickle charger. I use a motorbike DATATOOL charger, that will maintain the battery without over charging it. http://www.datatool.co.uk/consumer/products/products/index.php?product=battery Not sure if Halfrauds do them, but plenty of places on-line do. P.

The car is stuck in the garage unfortunatley, and im a fair distance from the OPC and any indys.. So, I can nip to halfords to see if they have a battery conditioner? can i get one like the Porsche one? (cant afford to wait for the porsche or an online one!)

I fitted a Bosch Silver 7HN (75AH) battery to mine recently, and it's fine. I got it from EuroCarParts, but found it cheaper in Cstco two weeks later - £45! Before you disconnect the battery turn the ignition key to position 1, otherwise the alarm will go off as the siren has a backup battery.

You only need a battery conditioner if you are leaving the car unused for lengthy periods. An ordinary battery chager is fine for your situation where you just need to top up the charge. That said, if it's suddenly dropped to 10V it's likely that a cell has gone & it's new battery time.

On some of the OPC used car listings I notice the 996's have quoted "Stronger Battery". [Welsh Accent] What's that then?

"Northern European" countries typically get a stronger battery. Cars imported from Cyprus and the like, have lower power batteries as they don't have to crank the engine over at -10C very often...

The standard Porsche (made by Moll) battery is 80 AH. I think they fitted a "stronger battery" (higher AH rating I assume) as an option (M197), or quite often it is fitted to Bose-equipped cars.

Thanks, Yes, I was afraid a cell had gone. Unfortunatley, here in Chippenham we only have a Halfords... no EuroCar parts or anything - I guess I can try and find the nearest on the web as halfords brand battery was up at 75 quid!

I'd forgotten that - good point...

By the way, can anyone give me an idea of how long the charging should take? no point hammering away at a lost cause, just wanted to give it a chance... Found a euro car parts in Swindon, so should be able to drop by Friday for a battery if i need one!

Hi guys, Thanks for the help, just checked and seems to have charged fine - back up to normal operating volts and the car starts fine. I havent braved taking it around to the petrol station yet though, wouldnt want to be stranded on the forecourt!

by the way does the fact it charged and showed 12-13V on the voltmeter mean that a, cell hasn't gone? and that once fully charged it should be okay?

Mine did the same. Charged up and started ok when it was hot off the charger. Leave it overnight and it struggled to crank. Unless you can explain the reason for it going flat (oops, left the lights on), then the revival is likely to be short-lived. Any idea how old the battery is? They sometimes mark the date on top.

Hi. Unfortunately, it looks like you have a Porsche battery, ie. you have a crap battery. Had exactly the same prob; never use the car, big flat six to turn over = dead battery. Had to get RAC Prestige out to start - but it never recovered as one cell was gone - which is probably the case with you. It's usually the cell nearest the positive terminal that dies. Even with one cell dead you're knackered. I had to get a new battery. I also learned a big lesson and got one of these. £20!!! http://www.maplin.co.uk/Module.aspx?ModuleNo=98358&C=Maplin&U=SearchTop&T=BATTERY%20CHARGER&doy=27m3 I don't have power outside my house - and even if I did, I'd have got one opf these. She now spins like a top every time I turn the key. In fact, I think that my battery has been "down" since I've had the car, as I've never heard the engine turn as fast as it does now. All the best. Adrian.

okay, charged the battery most of this afternoon. Checked with mobile phone video - light in boot goes off - so I can't find a reason for the drain. Checked voltmeter in car 12.5v Didn't start her, but have locked with boot on the catch, just incase when i get back the battery is flat Though i did notice the alarm lights on the dash were flashing 2 LED's rather than just one (even when car close properly), i wonder if that has anything to do with the problem? anyone help there? If not, then it does sound like this dead cell, so i'll be off to Euro Car parts for a new battery I guess... dont know how old it is, but its a porsche one.

The alarm LED will emit a double flash for a short period immediately after you have locked it with the remote, during which time the alarm is checking the status of its inputs and arming itself. If eg. a door switch is in the unhealthy state, you will hear a beep after the double flash period has timed-out. If all inputs are healthy, the double flash should change to single flash. You probably already know this, but have you waited a while to see if it reverts to single flash? When my 4 year old OEM battery expired after 4 years, there were no other symptoms other than the engine wouldn't turn over. However, mine hadn't dropped to the point where only the relays would pick up and then drop out - ie. click click as you describe. I think the LED double flash could be related to the low volts. As mentioned previously, there is a back up battery contained within the alarm unit which will set off the siren if you disconnect the battery. This will be a rechargeable type, Nickel Cadmium or most probably Nickle Metal Hydride. As you say your alarm has gone off - the battery is so low the alarm unit effectively interprets this as a disconnection, but there has not been any re-charging carried out since. It could be your alarm system backup battery volts have now also gone low and your system is advising you of a fault condition by way of a double LED flash? Hope this makes sense.

concept = great deduction!

The backup battery is in the alarm siren, not the alarm control module. The siren and tilt sensor (to the right of the car battery) are add-ons to the system (fitted only to the UK and Belgium market). RoW cars just have the alarm horn to the left of the battery. Because they are add-ons, the siren and tilt sensor aren't included in the diagnostic tests with a PST2. I agree that the alarm will do strange things if the car battery is very low, and could explain the double-flash. If the age and condition of the battery is questionable (and you have already had it go flat on you for no apparent reason) I would suggest that a new battery would be a good investment. It shouldn't cost more than 1 1/2 tanks of fuel if you DIY, and you will also have eliminated it as a cause of any alarm problem.

Thanks for that Richard - I had an awful time trying to get a battery today, luckily ATS had the one you stated in stock - though Im not sure its wide enough, but i will see - you can probably adjust the footing no? Anyway, I'm going to attempt the battery change shortly! wish me luck!

job done wasnt that hard - infact the hardest bit was getting the old battery actually out, it was stuck so fast I reckon its been there for the last 9 years! I just need to check on her tomorrow morning to check it isnt an electrical problem...

Nice one - but beware, if you don't use the car all the time, and then only for short journeys, your new battery will eventually suffer a similar fate. I would have a look at that solar charger - it seems to work really well.

Thanks, the car isnt used daily, but does get decent runs out with work and fun... Though a mate with a 993 has offered me his Battery Conditioner cheap, so i might take him up on that!

Well, all seems to be okay - took her for a nice 30 minute run today though, just to keep her in good condition you understand

Has the 'double flash' issue with your alarm system gone away after you changed the battery?

It wasnt a double flash - it was that it looked like there were 2 LED's rather than 1... and its still the same, so i figure i just didnt notice before..

That'll teach me to READ THE POST in future![X(]

I was referring to the alarm unit as a whole. I should have said 'system'. One of these days I'll get it right and actually manage to help someone, which was all I was trying to do anyway.[&o]

Concept You were absolutely correct in your deduction, and the contribution was a very valuable one. I was just being picky about the precise location of the backup battery which wasn't entirely necessary and I hope to goodness it didn't upset you. Please don't be put off by me being an old fusspot.

Not at all. Better an old fusspot than a touchy old fool like me! [8D]

After reading this thread, I connected my DATATOOL battery conditioner to the car on Saturday... left it on charge till this morning. WOW ! The starter motor span so much faster. I always thought it was a characturistic of these cars to have a bit of a 'weeer weeer weeer splutter brum" start. Maybe my original 70Ah MOLL battery is getting a bit tired. Paul

I'm waiting for my Porsche conditioner to arrive as we speak [ ]

In the nicest possible way, I'm so glad to see this string! I've recently had the slow turnover issue with virtually no turnover at all if the clutch pedal was down. The other day the whole thing went flat, I let a friends son wash and vac it and he had the radio on! Jump start got it going and all ok now but at least I know what might be ahead. This forum is awesome!