yes, at the shop in Van Nuys. According to the tool they used, there was no draw with the car off.

 

You know its never too late to recommend buying a digital multimeter...You can pick up a decent one from radio shack for like 30 bucks..

All the 100s you spent at auto shops the same info they charged you for your multimeter could tell you the same thing...

If your worried about not knowing how to use it just ask and someone will show you how to measure voltage, current / amp draw with it and you will learn how to use a multimeter and how to troubleshoot your car...

The months you spent fighting this thing probably would have shown up instantly on the DMM display it would have practically told you the problem allowing you pin point the primary issue in about 20 seconds.

-Gun

 

Just another thought, have you checked the ground strap to the engine? Two will not hurt. There is a possibility that it could be bad and that is what is causing the abrupt behavior with the alternator.

 

I once went through three quality alternators before I got a good one. It wouldn't hurt to swap it out. Again.

Did either shop look for an ACV component on the fluctuating DCV?

 

I would second the suggestion to check the ground strap (and the battery ground cable and connection).

As for 3-wire versus 1-wire, this is an interesting rant on the topic:
http://www.madelectrical.com/electri...hreewire.shtml

 

If the battery dies just sitting there it seems likely that there is some current draw all the time.
Same idea as Gun Jam here.
You don't even need a multimeter, just a simple 3 dollar test light.
Disconnect the positive battery cable.
Put 1 lead of the test light on the battery post. Put the other lead on the battery cable.
If the light glows, even a little, then the there is some current flowing all the time. It is really that simple.
The hard part is finding the current draw.

And make sure the battery ground goes directly to the engine block.

 

Start pulling fuses until the light goes out. When the light goes out, you have found the circuit with the draw.

You know, I had another thought about this problem. This is a chrome alternator with a chrome pulley, correct? Is it possible that the belt is so glazed that it is slipping when the alternator goes under a load to charge? You would think it would squeal but if the surfaces of the belt and pulley are slick enough it might not. That may account for the radical fluctuation in the voltages. Just one more thing to look at.

 

update: The alternator made a low squeaking sound while driving today, so maybe there is a problem with it. Good thing I already decided to send it back for a third.

Gun Jam: yes, after all this I will buy a digital multimeter and learn how to use it.

eleanor: what exactly is meant by ground strap? we're talking about an engine block ground other than the negative battery cable to the block?

Oxnard: what does "ACV component on the fluctuating DCV" mean?

65coupester: The last shop performed your 3 dollar test light test on the negative battery post. With the car off, the light didn't glow. Not even a little. To verify I opened the door to activate the courtesy light and the test light went on. Closed the door, test light off. So there should not be a draw when the car is off.

woody: I too would assume the belt would squeal as it has in the past if it was slipping, but I will check it anyway.

I'm going to send the 2nd powermaster alternator off tomorrow, won't receive the Tuff Stuff 140 amp until next week. I'll continue to check the wiring for anything wrong and I'll go buy a DMM.

Also, I have the positive battery cable going straight to the alternator, with a secondary cable going to the solenoid. Would it make a difference if I routed the alternator power through the solenoid? Can I do that? Hook both the battery cable and alternator cable to the positive side of the solenoid? I'm just brainstorming here.

 

There should be a heavy gauge wire or braided steel strap on the firewall that is bolted to the back of one of the cylnder heads. This is your body ground.

 

One note, I would change the wire from the alternator to the hot (front) terminal of the solonoid as well as the hot wire from the battery. Where you have it now is dependant on how much torque the battery terminal will support and I am guessing you are able to wiggle the cable with your hand (not good). On the solonoid, then nut will draw down solid and you will see less corrosion. The engine needs to have a ground strap from the body to the motor. I use two. On a side note, batterys can be bad even if they are new. A dead cell can draw a battery down and caust it to loose power in hours. I'm not sure how the automotive stores check this, but a specific gravity check on each cell will show it right away. The dead cell will stand out. Also I see the grond cable going down toward the radiator support but don't know where its connected. I suspect this may be a problem also, and if theres no ground strap to the engine, then thats what I would fix first before investing in a new alternator. Do you have a high wattage stereo?