Flat battery - after a new alternator!

Julio Geordio · Nov 17, 2009

Hi all,

Long time since I posted (the engine failure was on behalf of my friend and neighbour - soon to be ex 997S owner as he has it up for sale!), but hopefully you will allow me to pick your brains and experience!

My 997S is almost 5 yrs old, 53k miles, and has been pretty faultless (coil pack and battery excepted and expected so no grumbles at all). However, about two months ago I started to have starting problems, basically a flat battery, and I had to have it jump started a couple of times. The battery was only a year old, but I thought that as I had bought a Halfords battery (I was stranded and it was the only one I could get on a bank holiday weekend), then it may be that. So a month ago, after continued problems, I took the car to my local non-franchised, non specialist garage, only because I expected them to say "it's a battery problem", and just swap in a new one. However, they said the battery was fine (apologies, Halfords), and the alternator needed replacing (there had been no warning messages on my dashboard to indicate any charging failure....). So (long story) after having me by the short and curlies, they fitted a reconditioned alternator for £915. Guess what, today the car failed to start again! I had to be jump started in a dark car park.

There is clearly a battery problem, alternator problem or something else I don't know about. Any ideas or similar experiences?

My thinking is that I will go back to the same garage and get them to test the alternator only, nothing else. If they've fitted a duff replacement then they can replace it. If it isn't the alternator then I expect it was never the alternator and I will ask for a refund and go to my new favourite Porsche independent for their opinion.

In my humble opinion, it was never the alternator as a) after a good run, it was always good for at least a few days, and b) there were never any warning lights coming up.

Many thanks!

adrian996 · Nov 17, 2009

they fitted a reconditioned alternator for £915

Hi Chris.

Firstly, you have my sympathy as I'm afraid that you've been well and truly shafted by the garage that sold you that alternator. I had a NEW Porsche alternator fitted by my independent for just over £300 (yes, fitted also!). I'm pretty sure that my local OPC had quoted me circa £450 for the exact same part and job so I went to my indi - as you do.

It sounds like your car is regularly used (judging by the mileage and age) - is this right...? If not then your problems could literally be due to lack of use. Your car runs an alarm system and probably a Tracker of some sort also. This saps the battery of its energy over time if the car isn't driven regularly. Your problems then begin when you try to start the car (maybe after being sat idle for a fortnight) and she's slow to turn over - thus putting a lot of strain on the battery, bending the lead plates and making the cell (usually nearest the +ve terminal) fail. This all equals a knackered battery.

I would not go anywhere near the garage that you got the alternator from until you've had it independently tested. Are you with the AA or RAC? If so they should be able to do this for you FOC. If not then just find a local auto-electric dealer and ask them to test it for you. I strongly suggest that you do this so that you can see for yourself what voltage the alternator is kicking out when the car is a idle speed - it should be 13.5 to 14.4 volts. If it isn't then you do have a faulty alternator and a clear reason to ask for a full refund or new alternator. If they won't give you a refund I would suggest that you check the alternator model against one that your independent would have supplied you with to ensure that the garage has supplied you with the correct one in the first place.

The best of luck to you. Indi's from now on then, eh..?

Julio Geordio · Nov 18, 2009

Thanks Adrian

My usage has dropped massively in the last 5 months. I have only done 3k miles in that period, and the majority of my journeys are v. short. Whenever I go on a decent run, the battery (or start up in any case), is fine for a couple of weeks. I did wonder at the time if it was simply my low usage if it wasn't the battery.

Indi's all the way for me from now on. I would have gone there this time, except I naively just assumed that it was the battery, and would be a quick change. A (frigging expensive) lesson learned.....

matt643 · Nov 18, 2009

Its usually the regulator that fails. The rest of the alternator is very robust. The regulator was £37 for the alternator on my 986 when it failed a couple of years ago.

Julio Geordio · Dec 8, 2009

Update:

Still having problems with battery discharging so took it to OPC today. Turns out that the cable connecting the alternator to the negative terminal on the battery (I think he said negative) has corroded and basically it's losing 2v between the alternator and the battery. Cost of cable £58+ VAT. Labour cost to replace? £1,104 +VAT. Apparently the engine has to come out. They also said that the alternator would never have been a problem.

I don't know if I'm most annoyed with the crappy local garage who stitched me up on the new alternator, me for not going to an OPC or indie in the first place, or Porsche for designing a car where a frigging engine has to be taken out to replace a cable!

So, I'm speaking to my local indie, who doesn't think the engine has to come out and will confirm tomorrow.

Anybody on here had a similar scenario or know of any recalls?

adrian996 · Dec 8, 2009

Just wait to hear what the Indi says, Chris.

blueSL · Dec 8, 2009

No experience of a 997 but, normally, there have to be heavy gauge cables between the battery and the biggest drain - starter motor - and the (only) current source, the alternator. If the connections are loose, you get into a viscious spiral of bad connection, increased resistance, cable gets hot, corrosion sets in, connection gets worse and so on. All made worse when the engine and battery are at opposite ends of the car.

Let's hope the Indi can replace the cable without removing the engine...

JFK · Jan 7, 2010

Is the problem sorted now ?

I am having a similar problem with my 2004 C2S.

Did the engine have to come out ?

Best

JFK

pwebb · Jan 7, 2010

ORIGINAL: Julio Geordio

My 997S is almost 5 yrs old, 53k miles, and has been pretty faultless (coil pack and battery excepted and expected so no grumbles at all). However, about two months ago I started to have starting problems, basically a flat battery, and I had to have it jump started a couple of times.

Hi Julio, have you seen this thread? Your experience sounds fairly typical

http://www.porscheclubgbforum.com/tm.asp?m=517379

Ian W · Feb 2, 2010

ORIGINAL: Julio Geordio

Update:

Still having problems with battery discharging so took it to OPC today. Turns out that the cable connecting the alternator to the negative terminal on the battery (I think he said negative) has corroded and basically it's losing 2v between the alternator and the battery. Cost of cable £58+ VAT. Labour cost to replace? £1,104 +VAT. Apparently the engine has to come out. They also said that the alternator would never have been a problem.

I don't know if I'm most annoyed with the crappy local garage who stitched me up on the new alternator, me for not going to an OPC or indie in the first place, or Porsche for designing a car where a frigging engine has to be taken out to replace a cable!

So, I'm speaking to my local indie, who doesn't think the engine has to come out and will confirm tomorrow.

Anybody on here had a similar scenario or know of any recalls?

The engine DEFINITELY DOESN'T need to be removed. My 5 yr old 997S had problems charging last year - part of the problem was knackered bearings and diode pack in the alternator itself (refurbed locally with new bearings, brushes, pulley and diode pack for just over £100) and the other was an unusually high resistance in the heavy duty cable that carries the current from the alternator to the battery. This cable connects the back of the alternator then runs down the back of the engine to a junction box (on or near the side of the gearbox from memory) where it connects to a cable that runs forward to the battery. My indy (R&D, Manchester) replaced the cable and junction box whilst the alternator was away for refurb without moving the engine at all. Everything has worked as expected ever since.

JFK · Feb 9, 2010

Porsche Hatfield replaced the starter/alternator cable on my 2004 C2S for about £600 last week - the engine needs to be dropped apparently.

The difference between starting when hot or cold now compared to before is like night and day - the starter now spins the engine up with vigour and confidence is restored. I'm really pleased to have this long standing problem sorted with many heart stopping moments but only two batteries being needlessly replaced and one breakdown.

From what I hear expect to see more of this problem...

JFK