Would the 027 cause that much battery drain though?
It's not the battery 'drain' per se - it's simply the fact that lower capacity batteries simply can't 'store' enough power when the engine is running. Then when you stop the car and lock up, it can be up-to two hours later before all electrical modules go to sleep. And don't forget that TIM settings on your RDS head unit can draw power for two hours twice daily, even if the car isn't used.
The fact that not enough power was stored, systems running on, RDS auto updating . . . . and then two or three days later, your battery doesn't have enough juice to start the car.
Like I said, they are extremely sensitive to the correct spec battery. My GTI had the wrong battery fitted at the factory - instead of mine being fitted with the correct 72Ah, CCA 380A DIN, 640A EN/SAE spec, it was fitted with a 70Ah, CCA 340A DIN, 570A EN/SAE - and we would frequently be stranded due to a flat battery. After MANY visits to my truely incompetent stealer, banging my head against the wall to fit the correct battery, and being denied - I had to go to VW UK Customer Care, threatening them with Trading Standards regulations (not as described, not fit for purpose) - they then instructed my stealer to fit the correct 72Ah - and that correct item was perfect, and never let me down for seven and a half years.
Who sold you those incorrect batteries?
