olaugh

I recently bought a 968 with a charging issue. I am attempting to be a new DIY'er rather than take it to the shop at every issue and although I have poured through the forums i could still use some help. For background, the previous owner made me aware of the issue, said the alternator tested good and that he replaced the positive battery cable. The car has a winter garage charger that allows the car to be run for 30min before dying. When it is running, it is running good.

My MM shows the Batt voltage is fine at 12.6V but when running drops to 12V and 10.2V under heavy load. There is no significant voltage drop at the battery posts and they are all clean. However from the batt positive to the engine block or the alternator housing i get 12,6V. I disconnected the lead/ground from the alternator and get 0.1V from the batt positive to the end of the alt lead cable and 0V on the ground, which i believe means there is no significant voltage drop in the wiring harness and that it is good.

So does that mean the alternator is bad? Or any chance it could be the voltage regulator and can that be replaced without removal of the alternator? Or are there any other tests that i should run to confirm whats going on?

THANKS! Your feedback is appreciated in advance.

PaulD_944S2

Your description tells me the alternator is bad, very likely the internal voltage regulator.
The regulator is on the rear of the alternator with two small screws holding it in place.

The usual problem is the brushes wear out, typically after 100-125K miles. You can buy and replace the brushes but for the hassle it's easier to just buy and replace the regulator.

For a replacement regulator, check on Amazon, or a local auto parts store. The regulators usually run between $20-40. Watch out for fakes and knock-offs.

968workaholic

Did you check the starter connections? Probably a bad regulator, but doesn't hurt to check those connections

thomasmryan

see if the battery charger/maintainer/tender has boiled off the electrolyte.

the regulator is part number 928 603 142 00. when the brushes are worn to nubs, you might want to swap the bearings.

Moparboy72

I agree, Did mine the other year and the pair of bearings (6201 and 6303) can be had for under $20 from your local supply house. I used McMaster and their part numbers were 5972K42 and 5972K22 for the above bearings.

spanky

Not so fast to toss this unit yet, Under a very heavy elect load when the alternator is really working hard to keep up, a high current draw within the cars elect systems will equate to a drop in voltage from the source, this in normal.
The battery is just along for the ride being dead weight after the car has been started and is running doing nothing what so ever, the entire elect load is the being maintained by the alternator