Battery drain, changed stereo and now flattens battery.

[grim]

I took the stereo out of my s2 because it was a horrific silver faced monstrosity. But behind the stereo was an even more terrifying wiring job.

I found two wires that appear to be from the alarm system that were piggy backed onto the live and remote of the stereo. They are a black and a red, coupled together in a sleeve. I couldn't make sense of what these were as they had no feed when the car was running, but with the car turned off the black wire gets 12v in time with the flashing of the alarm led. The red wire appears to be an earth.

I left these alone and wired in my stereo to the original audi stereo live and earth. The stereo works, the alarm works. Happy days.

Left the car on the drive for the week, and this morning the battery is flat as a pancake.

I'm going to try and wire these two erroneous wires back into the stereo and see if this cures my problem. But my electrical knowledge is limited at best. What could they be for? Or is it an unrelated problem as it's a new car and this week is the longest I've left it unused...

Very vague but hopefully someone can shed some light on where to start.

[sidrick]

There's a lot of info on here about this Aftermarket stereos are perma-live in our cars and I think the solution is to take a switchable 12v feed from the ignition switch. I just take the faceplate off when I park the car and have never had a problem (I'm sure there's still a small drain).

I can't offer any help on your rogue wiring though as that'll probably have been some cowboy alarm install.

[grim]

I always turn the stereo off, it's an alpine that can totally turn off if you hold source. I'm hoping it could still be the radio drawing power though. That would be a lot nicer than trying to figure out when the hell else it is. Thanks for the reply!

[Error404]

it's an alpine

This is your problem. They are awful for draining batteries.

The alarm wiring sounds pretty standard and by that I mean shocking.

[rynaqui]

I've got a kenwood which turns on and off with the ignition, was a previous installation but seems good, car lasts a month without starting no problem!

[grim]

Well I've charged up the battery, and taken out the radio.

Now I play the waiting game.

[ManiacuV6]

put a amps meter in the place of the fuse for stereo. See what happens. Another try is to put the amps meter in series with the battery. Close the doors , close the stereo , wait 5 mins and see the current drawn . Use 20A DC scale and DON'T put the Ignition ON.
I think is something else. I have an Alpine and is current drawn free.

[grim]

Thanks, that's helpful advice. I'll give that a go tomorrow morning and see what's being drawn. I also think it's something else, most likely to do with the alarm.

[ManiacuV6]

IF you guess is an issue with the alarm system try to temporary disconnect it and measure the amps. You should have 0.02 A ( 20mA) maximum that is still ok. Less than 20mA and is even better.
IF is not the alarm system try to remove , one at a time , a fuse and see the reading. Good luck!