Radio circuit current drain

[atledreier]

I thought I had a bad battery since my charger never indicated full charge. Figured i should confirm it, and disconnected the battery. After a few hours the charger indicated full charge.
So... I figure I need an amperemeter and start pulling fuses? What's the best method to locate the short?


Edit:
Findings:
The radio circuit is the main drain of 0.68A
I have an aftermarket headunit (Pioneer 3700DAB) that switches off with ignition. It also seems to switch off the amp, as there is a slight pop at turn-on and turn-off.

[Simon the sparky]

To locate a battery drain, disconnect the positive battery terminal, connect a digital amp metre between the battery and the car, make sure everything is turned off and the keys are out, then leave for about 10 minutes. Now check the reading, it should be 0.0, anything more and your search begins.
Pull fuses to find the source of the drain, when you find the correct fuse, disconnect each item protected by that fuse till you find the problem.
If the drain can't be located by pulling fuses, try disconnecting the alternator.
Oh, I forgot to mention, start by disconnecting anything non standard.
Good luck.

[Simon the sparky]

Sorry, just re read my post, just to make it more clear, the amp metre goes between the positive battery terminal, and the positive lead you have taken off.

[bilko1]

You will always have a slight drain due to radio, clock and ecu memories. Each car is slightly different depending on spec. Mine which has RNSE and tracker has a 23 milliamp (0.023) drain after 15 mins. Just remember to flick the boot/ tailgate lock shut so the convenience unit shuts down. Also make sure you have the radio code before disconnecting the battery

[atledreier]

I have an aftermarket headunit. With the car as it stands I have a 0.68A drain when everything is shut off. Pull the "Radio" fuse and it's down to 0.08. Pulle the telephone fuse too and I'm down to 0.03, which is where I think it should sit. The radio circuit is definetly the bigger drain though. I need to test some more but I don't hava a garage and the snow came in pretty hard, so i'll try again tomorrow with the HU disconnected to see if it's a slow short or the actual HU/amp setup.

[Simon the sparky]

What make is your aftermarket head unit? Has it been wired correctly to turn off when the key is removed, or do you have to turn it off yourself?
If it's a Chinese head unit you've probably found your culprit!

[atledreier]

It's a Pioneer AVH-X3700DAB unit. It turns off with the ignition, and it sounds like it turns off the amps (BOSE) when it should too (slight pop at turn-on and off).

I still think my battery could be bad though, since 0,6A on a 110Ah battery means it should still be able to start the car after two days..

[Simon the sparky]

You may well have a battery problem, but you will always have starting problems with a 0.6 drain on your battery, this needs to be traced and reduced to no more than 0.05.

[ahoooga]

Charge your battery off the car till its full ( according to your charger) , leave it till the next day, then put it back on the car and see if it starts it.

Eliminate the battery first rather than chasing around looking for drains

How old is the battery in question ? original one maybe ?

[atledreier]

@ahoooga: Battery is an original Audi Replacement battery, about two years old.
@Simon: I have found the circuit that has the drain, so at least it's narrowed down slightly.But I'll definitely try your tip to eliminate the battery, thanks!

Last night it had snowed a little and I noticed a small patch of melted snow right in the center of the sunroof (solar panel). So SOMETHING is generating a small amount of heat in that spot. Anyone know what's there?

[atledreier]

So, I'm still at it with this issue.

The Radio circuit is the one with the most current draw of over 0.6A, so that's the obvious place to start. I have an aftermarket headunit and a BOSE adapter to use the built-in amp and speakers. I don't use the CD-changer, nor the navigation system and FM aerials, so I thought I might as well disconnect those to see if one of those units could be the source of the drain.

So, anyone have a diagram over the different units and where they are located? Will the car go nuts if these units go "off the grid"?

Anyone have any comprehensive info/diagrams of the radio circuit and it's different units?