I took the car down to Advance Autoparts to test it. The battery checked out GOOD, but had a low charge.

The alternator, when tested, put out .03 Amps.

I am getting a new alternator. But I need to DOUBLE check that the AL129X Alt is compatible with the 617 (300SD)

can anyone verify this one for me?

By what you posted, your alternator seems to be working fine.

I think there is a draw on the system somewhere that is sucking it down over long periods of time.

Trunk light?
Loose wires?

Your meter is just like mine...I believe it has a amperage setting where you can read the load.

Hook it up like this:

Attached Thumbnails

 

I agree with Brandon.

There is nothing wrong with the alternator if the voltage reads above 13.5V with the engine running.

Replacing it won't solve your problem.

Either the battery is not retaining a charge or the vehicle is suffering from a current leak somewhere.

I checked power drain/draw as in brandon's diagram...with my subwoofers/amplifiers and keyless entry relays all fused and wired in..my draw is .01 - .02 Amps

When it was tested at Advance it was tested at 2000rpms and at idle...i watched the meters..13.7-13.85 was the maximum voltage and the amps best was .03 amp.

Also-.02amp is not, i think, going to be enough to completely drain the system..and if the battery is not holding charge...this will be the car's 3rd battery in less than 6 years..something ELSE is causing a problem here.

a replacement 55-amp alt = 149.00
a replacement 115-amp alt = 168.00 (AL129x)

I dont know if this means anything or not..its an observation i made while at a gas station..when i revved the engine up above 1000rpms my headlamps got much brighter..as the engine settled they got dimmer...as i was pulling into the station...my speedo was acting up saying i was doing 35mph when i was braking and the tach stuck at 2000rpm while it was idling...after i left the station..arrived at my buddy's house the car refused to start (this all was on tuesday)

... just today I had to help someone jump their "dead battery".

The first thing I did was wiggle the battery terminal connectors. Sure enough the ground was just loose enough to die at startup, but ran the accessories just fine.

I guess my point is, don't overlook the simple things.

I'm guessing that you may have a short somewhere in the dash instuments. The PO on my 300D had to have the clock disconnected to keep her battery from constantly draing....M-B Indy went through the electrical system and that was the only way to keep battery charged.......

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."

my drain..even with everything i've added is only .02 amps...
i drove the car at highway speeds for quite a good amt of time...turned it off..and within 30seconds it wouldnt start...

i think it might have been the fact that the systems in the car wernt getting enough power to run properly caused them to go haywire..it only did this once..it hasnt did it since..

Now...when your car won't start...does everything else in the car "show" that you are having a dead battery or is the starter just not doing its stuff?

I would go over your ground and positive terminals with a fine tooth comb. so to speak. Also check the engine to body ground strap. Make sure its solid.

the starter aint doin its stuff..lol..it tries it really does then it wont and give up..the locks cycle..my deck looses it settings...(grrrr i hate that)..and thats bout it....lights dimm somewhat..

that right there sounds like the batt doesnt have enough AMPS to crank the starter enough but enough to run the lights and etc(s) in the cabin...

Okay next time it does this, hook up your volt meter to the battery (directly) and see how much voltage you have before, during, and after cranking.

Check your gounds, the wiring point beside the turbo on the fender (4 phillips screws under a black cover passenger side) and also the alternators connector, etc.

take off the wires and clean the terminal?

Sounds like the alternator to me

__________________
Jason Green
1977 240D AUTOMATIC the Beast
1974 Super Beetle



Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself.
- Mark Twain, a Biography

Owning a VW you should know, when you rev the car and the lights get brighter...thats an indication of the alternator working

Also indicates the battery was low on V when you started

You have some problems with the test procedures.

If you connected the meter properly per Brandon's diagram, the meter will read approx 50-100 milliamps. The clock, by iteslf, can draw this amount. If you have a stereo with a clock and a memory, you will be up above 50 milliamps for sure. If you are measuring 20 milliamps, my suspicion is that there is some operator error happening with the meter or the meter is not functioning properly.

Advance found 13.70-13.85 volts. This indicates a properly functioning alternator and the output from such an alternator will definitely be above 5 amps at that voltage. When you state that the output was .03 amps, clearly operator error has again returned to affect the results. There is no possibility of 13.70 volts with a current output of 30 milliamps.

So, my conclusion to you is that the alternator is in proper working condition. Nothing else can be concluded due to erroneous test procedures, and/or improper test equipment.

Brian,

I will redo Brandon's test and then I think ill take the car down to AutoZone and see what their starter/alt/battery test turns up...

I will post pictures from Brandon's test so you can verifiy if the way im doing it it correct.

Kris