Battery drain on a 05 audi a8l quattro
 

Hello all. I bought a 05 audi a8l special edition about a year ago. Six months after I bought it the battery kept dying almost every other night. I switched the battery after about 5 months of that. The new bettery has been replaced for about four months. It has now started dying again. All vital signs are good (Battery, alternator, and no serious drainage when turned off.) I assume the drainage I am getting is from the climate fan when it is turned off. Now it is dying every single night. Any help would be much appreciated.

Update, the instrument cluster lights stay on. They flicker like they want to turn off. But they never off.the vcds doesn't tell me much about that.