Problem with battery charging. I had the alternator replaced with a new bosch alternator. Seemed to work fine for a couple of days. Now when I start-up the car it charges OK. After it warms up the voltage slowly starts going down with no A/C or light on. If I turn it off and let it sit for a min. it starts putting out 13volts or so. It seems it has the same problem I had before except before I had it replaced it would not put out 13v for more than a couple of min. It seemed to be going bad. The battery is less than a year old. I pulled it out and had it tested at the local auto parts store. The guy said it was ok, a little weak. So I put it on a charger. Gave it a full charge then its fine for a day. After I turn on the A/C and lights voltage goes down between 13-12v. The voltage jumps around all the time, +/- .6v. I have the Durametric reader.

Any suggestions other than checking the terminal connections in the battery compartment?

Anyone had issues like this.

I was going to get a new battery but the old battery is still under warranty and I was pretty sure they would test it. It tested OK

02' C4s
TTKEN

 

did you replaced the regulator along with the alternator?

 

Don't know. I had it replaced at a local shop. Is the regulator extra? Would it not come with a alternator?
Thanks
TTKEN

 

A new generator includes a regulator so you should be set. Does the voltage ever drop below 12V? It's normal for the reading to be in the 12.5 V range. If you're above 12V you're fine.

 

Never falls below 12 but with a/c and lights, it gets close. Before I had it replaced it did get below 12.5v.
Thanks
TTKEN

 

Just a fyi, dont plug in accessories to your cigarette lighter as this will pull volts from your alternator, and do leave any cell phone chargers plugged as this is also a parsitic draw on the electrical system. It seem like a faulty regulator, if you bought the alternator new and registered it with bosch, they will replace it with no charge. I would start there. good luck.

 

What acces. are you running?... Aftermarket Stereo, amps, component speakers, etc?... If so we had a similar problem that we traced back to a shoddy stereo install job that was sucking voltage... It took quite awhile to get to the bottom of but the owner purchased the car with the system already installed so we started double checking everything just to be sure.

Also, if ever in doubt replace the battery. It's cheap insurance and 996's and 997's are EXTREMELY picky about having a strong battery. It will leave you stranded if voltage is even slightly off.

Good luck.

 

hmmmm, how old is the battery... maybe you should swap that. It will narrow down the prob even more.

 

The bats less than a year old. Its a name brand, 100 buck bat. When I say accessories I mean the A/C and lights. I drive 23 miles each way and by the time I almost home its @ 12.5v. I've been charging the bat every night. I'm going to try and return the bat this evening. I hate taking time off from my time off to get the car fixed. Thanks!

 

Sounds like you really do not have a problem. If it drops less than 12v then you have a problem. Your reading should be between 12v - 14.2v. From what I remember, 1v = 1.2v which equates to a total of 14.2v. But as long as you are between 12-14 your fine. I have also seen overcharging alternators... kinda rare but I have seen it.
Good Luck

 

 

Yes....that is why when you check a 12v auto battery it reads 14 ish volts and not 12.. because 1v is actually 1.2v.

 

I have no idea what win is talking about in terms of 1v=1.2v. Are you saying that the gauge in the car is off relatively to a good meter?

I really don't think you have a problem. You have a 12 system. Your battery is at or above 12v. Your alternator is charging the battery as it should from what you've said.

If you see lights getting dim, or accessories impacting the level of your lights, or hard starting I think you're just over thinking this.

 

As I stated in my previous comment... I do not think he has any problem. As long as his reading between 12v-14v he is fine. It is normal for your voltage to drop a little when you use extra accesories.
Agree.... I think he is just overthinking this....but if you find a problem..post it. Good luck