Is there a quasi-easy way to find the source of the drain? I know in the automotive world, the words "Easy" and "Electrical Problem" are like oil and water. I'm just sick of having to charge the battery every morning and carrying a jump pack around in the trunk. The alternator's a bit weak, bit that would have nothing to do with a drain while the car is sitting overnight. Anyways, thanks for the help.

Have you load tested the alternator? How new is the battery? Does it meet minimum OEM specifications?

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Theres more details to what the parasitic drain should be, i cant remmeber off hand but its very low (less than 1 amp for sure, probably like .02 amps).

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You can isolate an amperage drain relatively easy. You need a good ammeter and most decent ones will handle 10 amps. First thing to check is the amp draw right at the battery. Remove your positive terminal and place your ammeter inline with the B+ cable and the B+ on the battery so all current your car is drawing is going through the ammeter. DISCLAIMER: DO NOT ATTEMPT TO START THE CAR WHILE WIRED LIKE THIS OR YOU WILL FRY YOUR AMMETER OR AT LEAST BLOW IT'S FUSE! You should see something under about ~.05 amps if all is well. Make sure the interior lights are off (doors closed), trunk closed, and the hood light disconnected to get your baseline reading. If you are seeing .5-1 amps or more you have a draw somewhere that can kill your battery. If it is draining from fully charged to dead in the morning you probably have a drain of several amps (assuming your battery is good and not the problem). You can get an idea of what some circuits draw by turning some things on, one at a time. For instance, opening your door and turning on your interior lights should show a few amps draw, headlights on should show up around 10 amps, etc. Since your battery is draining when your key is off start by trying to find the circuits that have power then the key is off. One at a time you can pull fuses to circuits that are powered when the key is off and note the amp draw. If no change reinstall the fuse and try another. Keep doing this until you find a circuit that changes your amperage draw at the battery. Since you will have to open your door to pull fuses you might want to start with the dome/interior light fuse and see if that takes care of it. If not just leave it out while you try the other fuses so you don't have to keep waiting for the dome light to shut off when you close the door after pulling out another fuse to check your new amp draw.

There are also many fuses next to the battery that you might want to start with since they are close. Also, you can pull the large fuses and remove power to the entire interior. Keep trying various fuses until you find it. Don't forget the two Black/white wires plugged into the B+ cable. Your goal is to find a starting point and follow it back to the source. I don't have my ammeter with me right now or I'd get some baseline #'s for you. Maybe I'll do it later when I get home.

Modified by qsiguy at 4:01 PM 4/2/2008

94 Q45 162,000 miles.........................................90 Q45 242,000 miles

Upon connection the dome turned on and stayed on due to my aftermarket alarm until I armed and disarmed it. Then it turned off. Also, there are apparently some systems that operate for a couple minutes upon connection of power as the amps take about 1-2 minutes to stabilize at the low level.

Initial connection w/alarm disarmed, dome light on -> 3 amps, settled to 2.6 amps

Aftermarket alarm armed, dome light off -> .24 amps then settled to .066 amps after approx. 1 minute.

Alarm disarmed, dome light off -> .063 amps after 1 minute

Start pulling large fuses in under hood fuse compartment, unless noted I reinstalled the fuses prior to pulling the next fuse/relay
"IGN SW" 30A fuse -> .056 amps
"ENG CONT" 25A fuse -> no change
"INJ" 25A fuse -> no change
"COND FAN" 30A fuse -> no change
"MAIN" 75A fuse -> .043 amps
"MAIN" and "IGN SW" -> .035 amps
*When "MAIN" reinstalled amps were at .5 amps 2 minutes then settled back to .063 indicating that a circuit was operating for a couple minutes upon power up, ECU?
"Power window" fuse -> no change
"Anti Skid" fuse -> no change
"Blower Motor" -> no change

Small underhood fuses
"Eng Cont" 10A fuse -> no change
"Fog Lamp" 15A fuse -> no change
"Room Lamp" 10A fuse -> no change (unless the dome light was on already)
"Tail Lamp" 10A fuse -> no change
"ALT (S)" 10A fuse -> no change
"Hazard" 10A fuse -> no change
"Horn" 15A fuse -> no change
"Headlamp LH" fuse -> no change
"Headlamp RH" fuse -> no change

Relays underhood in junction box (same box as above)
"Anti Theft" -> no change
"Cond Fan" -> no change
"Cruise Cont" -> no change
"Inhibit" -> no change
"A/C" -> no change

Miscellaneous
Trunk open w/trunk lamp on -> .4 amps (amps fluctuating +/-)
Room lamp fuse out, door open -> .233 amps (might be alarm LED drawing)
Room lamp fuse out, door open, park lights on -> 6.2 amps
Headlights on -> Exceeded 10 amps, couldn't get accurate reading

This should give you a good start on tracing the amp draw. I didn't pull the two really large fuses next to the fuse/relay box (100A+) or the two black/white wires plugged in at the B+ terminal.

How is the alternator defective? Loss of a phase [1-3 diodes blown open?] or the regulator has failed or a brush has worn out or the cummutator has high resistance shorts?

When a diode shorts there can be a high reverse flow back thru alternator from battery...........when regulator short there can be a few amp reverse flow.

Which is it?

Disconnect the alternator from [2 circuits] and see if it goes away.

As to trouble shooting a short [small current flow] you can either spend a few hours [take detailed readings and written notes] or have someone else do it and add an hour or 2 charges for processing your car in and out of shop.

That's more like it...

0.3 amps of continuous drain would discharge the battery in a matter of days, rather than weeks...

Found this handy little item at Jaycar. It's an ammeter that plugs into a standard blade fuse slot to check or current draw. Pretty cool gizmo although it would be simple to make an adapter that connects to your multimeters leads and plugs into a fuse slot.

http://www.jaycar.com.au/produ...D=619

I haven't realy taken a detailed look into the alternator, but I had a local tech take a reading and it was only putting out about 2.4 amps.