VW stock batteries.
VW uses a battery that's hardly large enough to power some of the electrical components in normal temps let alone all the cold weather package components in very cold temps. When replacing your battery, and replacing your battery will eliminate all of this,( I never notice it at all anymore)replace the stock one with the battery thats used in the Diesel model. It has way more cold cranking amps and way more reserve power. It can adequately supply power with only a small infrequent charge by the alternator. It does not cause the massive 14.6 + volt charge every 2 minutes that cause the headlights to dim and the fan motor to slow down. I was in Montana and it was -35 degrees F. I unlocked my car with the remote and turned the key to on and let the fuel pump get the fuel rail up to pressure. 5 seconds or less. I then cranked the engine about 4 turns only and it started right up. The speed of the starter was much faster even in this extremely cold weather. I know that the Mobil 1, OW40 European formula synthetic helped here too. I turned on my seat heat, the mirror heaters, the rear defrost and all the lights, high beam and fogs and drove off slowly. I turned the heater on at the very first sign of any warmth and had the fan on 3. I experienced no dimming or lack of a voltage supply. I highly recommend this upgrade. The Diesel's battery is only slightly larger in dimension but it does fit with some wiggeling and presistance. Of course the power steering reservoir must be un bolted from its mount and moved over to the left as far as possible just as in all battery replacements. No need to disconnect and remove from car. Now that Sears handles Optima batteries, we can all get the big boy battery for a very inexpensive install charge...This larger capacity battery stabilizes the entire cars electrical systems that includes the Engine management computer, bunches of sensors, actuators, switches and modules. It is a vey good up-grade for everyone, no matter what engine they have... JK