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Charging query

S

Spookymooo

New member
Joined
11 Sep 2013
Messages
23
2005 997 C2 3.8S

Following the appearance of "battery charging" warning I have started to remove the alternator to ascertain which regulator to order (following advice from helpful forum member)

I have also seen threads concerning the failure of a starter motor to alternator cable which has been cited as a common problem on early 997s. (Caused by overheating, leading to conductivity breakdown)

How could I confirm the cause of this problem before I start buying bits and pieces?

Cheers Rob
 
I think you should start with a multimeter and look at the voltage, usually about 12.5 Volts without the engine running, going up to around 13.6 Volts with the engine running.
 
Voltage read outs

Thanks for advice.

I've just tested the voltage and measured:

Battery voltage with engine off : 12.5 volts

battery voltage with engine idling : 11.8 volts

Battery voltage at all rev ranges : 11.8 volts

Definitely something wrong here. Can I safely assume it's the alternator or regulator?

Cheers Rob
 
I expect this to be a problem with the alternator, it isn't charging the battery. If you are removing it check the brushes for wear or if they are sticking in their holders. I would assume that the lower voltage with the engine running excludes the earth strap from your problems .
 
Spookymooo said:
2005 997 C2 3.8S

Following the appearance of "battery charging" warning I have started to remove the alternator to ascertain which regulator to order (following advice from helpful forum member)

I have also seen threads concerning the failure of a starter motor to alternator cable which has been cited as a common problem on early 997s. (Caused by overheating, leading to conductivity breakdown)

How could I confirm the cause of this problem before I start buying bits and pieces?

Cheers Rob
Click to expand...

Hi there
Have you sorted this yet ? This exact thing happened to my 2005 997 C2s.
The other symptoms my car had were:

1. Slow to non existent cranking on hot start (OK ish when cold).
2. Battery needing constant top up charging.

When I tested the voltage at the battery = voltage at rest 12.5v, voltage when idling 11.8v, voltage @ 2000rpm 12.8v.
But the important aspect for my particular issue, was the voltage at the alternator at idle was 13.5v !

This meant that I was having a voltage drop from the alternator to the battery of around 1 volt.
This was the conclusive proof for me that the alternator cable was at fault. I googled 997 alternator cable and found a brilliant article with write up and picture sequence on how to replace it.
I went to my local dealer and they had one in stock (upgraded part number, so a known fault) it cost £80. I fitted it and it has totally transformed my car. I get 13.8v at the battery so it charges itself completely now, regardless of what type of journeys. But the biggest improvement is in the starting of it, it used to crank over really slowly (ridiculously slowly starting it when hot) to the point that I never really had confidence that it would definitely start ! But now it cranks over like it is on steroids !! cold, hot, or just after turning it off, at all times it is perfect.

I think that this problem affects a lot of 2005 2006 997s and it is only when it gets really bad and stops charging the battery that people have to sort it.

I hope you have already sorted out your car but if not I hope this is of some help to you or anyone else having this issue.
It has completely transformed my ownership from having worries about flat batteries and worrying if my car would start, to now having total confidence in any journey of any distance.

Andy.
 
Success

Cheers Andy,

The problem was the alternator, the windings had gone open circuit and it was totally useless.

I managed to keep the original shell and a company in Bristol called "Sparks" rebuilt it for £150 maintaining original spec and appearance.

Before the alternator was done I was experiencing the odd stall at low revs...since replacement all fine so I guess the electrical demand was being starved at low speed and caused a cut out.

Out of interest, how did your new cable differ from the original. Was it difficult to refit as I've heard it can be a bit of a nightmare.

Cheers Rob
 
Re: Success

Spookymooo said:
Cheers Andy,

The problem was the alternator, the windings had gone open circuit and it was totally useless.

I managed to keep the original shell and a company in Bristol called "Sparks" rebuilt it for £150 maintaining original spec and appearance.

Before the alternator was done I was experiencing the odd stall at low revs...since replacement all fine so I guess the electrical demand was being starved at low speed and caused a cut out.

Out of interest, how did your new cable differ from the original. Was it difficult to refit as I've heard it can be a bit of a nightmare.

Cheers Rob
Click to expand...

Hi Rob. That is great that your car is sorted, and the rebuild has saved a lot of money so that is really good.

As for the cable, it was quite different from that original, the cable itself was slightly thicker but the biggest difference was the cable ends (fixing points that bolt to the alternator, starter and the joint on the gearbox) and the way that they were crimped onto the cable, much more substantial !!

I was very nervous about taking on such a big job on my new to me, dream car ! I am a competent DIY mechanic and it was quite a long job BUT I followed a brilliantly written article that I found, which included pictures and to be honest if you take your time it was actually very straight forward in the end. As a result of this I would be very happy to work on my 911 as they are brilliantly thought out cars to work on.
So in a nut shell, the alternator cable is definitely NOT a nightmare to do, IF you take five minutes to read that article or five minutes chat with someone who has done it.

Cheers Rob.

ps if anyone has this issue, here is the article.

http://www.6speedonline.com/forums/997/289189-3-8s-how-replace-alternator-cable.html
 
Just a word of caution. Alternator cable change is fine on a manual but a dog to do on a tiptronic as the gearbox has to be lowered. I learnt this the annoying way having followed the same instructions which are for a manual. Had the helpful indy do it and hot starts are much better.

Nick
 
My car was overcharging according to history and the alternator changed, everything tickety boo at the moment.
Another example of cutting corners with cheap suppliers to make a few more Euros (Deutschmarks) :x
Great article, that's why this forum is so good :thumb:
 
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