Comments welcome...
Last Friday I used my car, came home from work, locked it, it sat all Saturday, went to go out Sunday and found car wouldn't unlock. Popped the driver door handle cover off to expose the key hole and got in, key in ignition, and nothing coming alive. OK, dead battery??
I get my girlfriend's car in front, hook up the jumper cables, MFD and radio come alive with key in ignition. Start her car, go to start my car, and all I get is clicking noises. Then errors on the MFD screen : Tire pressure monitor system error, AFS lighting error, cruise control error, brake error... bunch of errors. Car won't start.
Use my free subscription to VW-connect to ask for tech help. They say that it's the immobilizer, and that if I didn't start the car within a certain amount of time from when I unlocked it, that I am locked out. Hmmm? They send a tow truck to bring to me a dealer.
Tow truck shows up, asks what the problem is. I tell him VW thinks its the immobilizer and I need to go to the dealership. He asks if the battery was dead, I tell him yes. He pulls
this little unit out from his pocket, connects it to the battery, and jumps the car no problem. I'm baffled because 1) the booster battery is no bigger than my cell phone, and 2) why didn't the jump of the car work? He says new cars use too much power with the alarm, GPS, computers, etc and that if the other car was using the battery for it's own services, there wouldn't be enough power to jump my car. What??? Basically, I can't jump a modern car anymore. HUH?
Ok, whatever.... all week I'm thinking about this dead battery. The doors locked on Friday after work, so I didn't have a door open. No lights are set to be on in the car. No cell phone left plugged into 12V outlet... So what drained the power? No idea.
I plug in my OBDEleven and see I have a bunch of error codes for all modules in the car. I reset them all. All errors are gone.
Fast forward to end of the week. Come home Friday, park the car, lock it. On Saturday afternoon I go to start it, and get the same clicking sounds as before. This time no warning on the MFD, but all the idiot lights are flashing. Then on the radio I get a warning that the 12V battery is low and almost depleted. WTF? It's now hooked up to a battery charger. Charging at 12V 2.8A (1/10 the battery capacity of 280A --- why is this battery so small?), and battery voltage shows 11.73V.
I've had the car about 9 weeks, changes include a couple tweaks via OBDEleven (mirror dip in reverse, comfort open/close windows with remote, kencha tails, ignore bulb-out warning on license plate lights) and changed the glove box, backup, and license plate light bulbs for LEDs. I moved a fuse so the 12V outlet in the armrest is always active, but I didn't have anything plugged in except a USB adapter - it has a small LED on it. I also did leave my OBDEleven device plugged in, which emits a faint orange glow, so there is a small LED there. But I wouldn't think these two LEDs are draining the battery in 24 hours.
Nothing has changed in the last week to suggest why the battery is suddenly going dead. Annoyingly it only happens on weekends when the dealerships are closed. I called the local dealer about the last dead battery and he said he needs to diagnose the problem, and can't give a firm estimate on time, but I'd have to drop the car off and leave it. Hope this would be a warranty issue.
Has anyone else had similar problems, and what did you do to solve it?
TL;DR : 8-week old GTI, battery is going dead in 24-48 hours when car isn't being used. What to do?