Charging System Issue

[elemgee]

I have a 94 SVX and have have a charging system issue which I think I've unknowingly had for quite some time. Many times over the past few months the engine turns over slowly before starting.

Let me start by saying that I have the alternator wiring upgrade. About a week ago all of my dash lights came on when I was stopped at a light. And occasionally my semi-high output stereo (500 watt amp) will cut out. The next morning I charged the battery, attached a voltmeter to the battery and it read about 12.2 volts with the engine off. When I turned on the engine, the voltmeter read 11.5 volts at the battery. With the engine still running, I moved the positive line of the voltmeter from the positive battery terminal to the top of the alternator - where the cable from the positive terminal of the battery screws in - and it read 15.7 volts.

So it seems that my battery isn't charging (due to the low reading at the battery when the engine is running) but that the alternator is putting out current. Any idea what the problem can be? I should also mention the battery is about 4 years old.

Thanks.

Larry