I still have the original battery in my C4S which has a production date of early 2003 and in-service date of 7-2003. The car is always plugged in with the 2 amp float charger whenever it's parked in my garage. I put on about 2k miles in the Hill Country over the past weekend. Totally I have 21k hard driven miles on the clock now.

When I start the car hot, I notice the engine has a hard time cranking over and some times it takes 2 cranks to start the car. I got worried. So I start to monitor the volt meter. It used to hit high 13s near 14 when driving and starting voltage is close to 13. Now it hovers at below 13 when driving and starting voltage is now 12 even. Not good.

After getting home, I plug in my Black and Decker charger that has the battery conditioning function. It ran for longer than I expected of a day and a half, then it went into charging mode for about 1 hour.

It worked. No more cranking problem. No more low voltage.

Just wanted to share.

 

I'd consider replacing a 6 yr old battery. You may not get advance warning when it finally dies.

 

Yea. That is my worry but I do want to see how much longer it will last. Maybe set of record or something...

 

Don't be an idiot. Just replace the battery.

 

Well, in theory, a battery does not die unless the lead plates have crystal deposite covered and ultimately short itself out. The crystals starts to build as soon as the voltage is below optimal (when ions are low). So if it is constantly charged at peak voltage, then the ions in the acid should be okay forever. I have a 2000 M5, that battery is a few years older than 6 years old and it has no problem so far because I regularly run maintenance on it and float charge it all the time. I just checked it and the "window" on it still shows bright green. Perfect health. Why change it if it aint broke right? I'll report back when either one ultimately dies. Don't hold your breath.

 

Alex, are you using a multimeter or the in-dash voltmeter to measure voltage?

If voltage measures 13v or less at idle, then your alternator may be on its way out. If voltage measures 10v or less during startup, then your battery is going bad.

///Michael

 

I was reading the in dash volt meter. That's what I thought but for the alternator to fail at 21k miles is not really likely. So I was glad that reconditioning the battery make a difference. If it reads 10V, I doubt the car would start. It now reads close to 13 when engine is off and close to 14 @ idle.

 

Before I bought my 996 about a year ago, I test drove several with varying mileage and conditions. They ALL cranked over slowly like the battery was low on charge. Perhaps the slow cranking is normal?

 

Well, I had mine for 6 years now. The cranking was especially slow when the voltage was low. It sounded like it was as if it was cranking one cylinder per 1/2 second or something like that.