Volkswagen Repair: VW Jetta Battery Replacement, volt lantern battery, jetta vr6

Question
I am going to replace my weak battery on my 2000 Jetta VR6 and was curious if I need to hook up a trickle charger to cables before I disconnect them to avoid the radio locking out or any engine computer issues?  Sounds like a hassle, but thought I heard certain years (and/or models) will have issues like that.  Any additional tips would be appreciated.  I have replaced many batteries but just wanted to be sure on this one.  Thanks in advance.  -Jeff

Answer

Memory_Saver Jeff,
  Yes, this is a problem, therefore you should use a "memory saver" auxiliary battery.  Do not use those cheap units based on a small 9 volt battery, there likely won't be enough current capability to support all the systems for very long.  You don't have to spring for a full size auto battery; you can make your own with a 12 volt lantern battery connected through the cigarette/aux power port.  However, make sure there constant power to the port with the ignition OFF before you depend on it.  See the diagram on how to set this up.  A Radio Shack 276-1661 rectifier diode is more  than sufficient; make sure the diode lead opposite the "white band" line is connected to the battery + terminal.  
- Rick