neunelf

At idle my battery is receiving a 13.2V charge instead of a needed 14+V. Because of this my new Optima yellow top battery naturally ran out of juice, but has since taken a manual charge just fine.

The alternator belt appears reasonably tight without noticeable slippage and the battery has a solid ground.

So my question is: Is my only option replacing the starter or could there be something else causing a weak 13.2V charge?

Ray Calvo

Starter replacement won't help; alternator might.

Apparently, the regulator is available separately from the alternator. However, problem could be with either; bring it in to a shop to have them troubleshoot.

neunelf

Opps, <img src="graemlins/c.gif" border="0" alt="[ouch]" /> I should have proofread more carefully (I will resist the urge to now edit my post)
I didn't mean to say "replacing the starter..." I meant to say "replacing the alternator..." Focus Brad, focus.

Thanks Ray, I didn't even consider the regulator. That could be good news. I have just single mindedly been preparing myself to install a new alternator.

Is the regulator built in as a part of the alternator? And, any simple way for me to test the regulator with the volt meter by reving the car?

Ray Calvo

Couple more data points from a drive I just took: I have a voltmeter that plugs into the cigarette lighter. I hadn't driven my 993 for a week. ON startup, was reading about 13.5V; stayed there at start of drive, then started going up. After about 90 minutes of driving, the voltmeter seemed to settle at 14.5V.

These 993's seem to have some high battery loads after shutting off the engine; I have heard of a couple of folks who drained the battery just by letting the car sit for a few weeks - and it happened to me.

Troubleshooting between regulator and alternator? Beats me, exc. using a inductive ammeter to see what amperage the alternator is putting out. Unfortunately, this needs you to access the power lead directly off the alternator - and guess where that is!

Regulator appears to be bolted onto the back of the alternator.

E. J. - 993 Alumni

Brad - If you do determine that you need a new alternator and you are going to diy the change, I bought a rebuilt Bosch unit at Autozone for $175 (after core exchange)that matched the factroy Bosch unit one exactly. That was 18 months ago and no problems. I think The part department at the dealer wanted $900 for a rebuilt one. The Autozone one has a lifetime warranty too. They have the part numbers for our cars - just tell 'em what year you have.

Good luck.

E. J.

neunelf

Thanks for the info Ray and E.J.!,

After a couple of hours scouring the history I did finally run across some info on the alternator/regulator, most of it from the 911 forums.
It's frustrating because I killed an OEM battery that was less than 2 years old and now the new Yellow top was drained after a few drives.

Ray, I also have a plug in Voltmeter somewhere in the house. I'll try and find it and compare it to your results.
E.J., good tip on the rebuilt unit at Autozone. I have used rebuilt items before but not on the 993. With your success I will definitely go that way if the alternator is the culprit. And to think they give you a Lifetime Warranty! Little do they know I may keep this car for a lifetime.
Thanks again guys! <img src="graemlins/wave.gif" border="0" alt="[byebye]" />