Chasing parasitic draw

[Quickstep192]

I'm hoping somebody can help me with a parasitic drain issue I'm having. It's on my daily driver Audi, but not much help on that forum, so I hoping for some live here. It's in the same family, right?

I tried taking the negative cable off the battery and putting an ammeter in series, but when the battery gets disconnected everything changes (I can hear relays clicking) so I can't seem to get conclusive results.

I've tried measuring millivolts across the fuses but don't see any unusual m asurements.

As a last ditch effort, i put the ammeter back in series and started pulling fuses. Even after I pulled all the fuses, I'm still seeing drain and when I put the terminal back on, I get a pretty decent arc, even with the fuses pulled.

What's left? I've read about bad alternator diodes causing parasitic drain. How would I diagnose that?

[911obgyn]

pull the large red wire off of the alternator. I have used a lightbulb and socket to check for battery drain, wire it across the negative battery terminal, you can see the lamp light up, clocks and electronics show with glowing pulses.

[Tea Tray]

Make sure car is off - then.. Disconnect either battery terminal. Take a regular 12 volt test light and hook it to the battery wire and battery post. If the bulb lights then there is a current draw. Keep in mind that one or more circuits may be drawing power.
Here comes the trick.
While keeping an eye on the test light, disconnect one fuse at a time. If the light dims but is still on, that circuit has draw and there may be others. When the light goes out completely, you have found the circuit with draw.
Wanna double check?
Once all circuits have been verified, the light should be off. With the test light still in circuit, turn on the lights or some other load. The lights or other load won't operate but the test light will light up.

[tirwin]

Couple of thoughts...

There may be other draws than what is wired to the fuse box. For instance you might have a car stereo amp with a separate in-line fuse.

Modern cars have a tendency to have some circuits remain active for several minutes after the car is turned off. That can also complicate determining what a normal s abnormal draw is.

[billybek]

I was chasing a draw down on my wife's Nissan and used my inline amps feature on my old Fluke meter.
Like you I found that breaking the circuit then connecting the meter inline would change things. I also wanted to run the meter on milliamps and thought the inrush would take out that very expensive fuse when completing the circuit with the inline meter.
Loosened the negative post and kept contact between the clamp and the post, not allowing the circuit to be broken.
After that, I started to pull fuses to see when the draw disappeared.
Turned out it was the alarm/remote starting module that was causing the problem. I suspected as much before I had started but had to make sure.

[steely]

Just an FYI, They make a clamp-on ammeter now that is reasonable if you're up for the small investment.
They're decent and convenient (and safer) as you don't have to disconnect stuff..

[Tremelune]

You're gonna want to hound that Audi forum. What kind of car is this? My Cayman does insane things with draw when the car is parked.

One tip I can offer: get a charger like the CTEK that has a "Supply" mode to provide power to the car. You attach it to the terminals, then remove the battery, and the car never loses constant power. Modern cars seem to freak right out when they lose power.