I sent an email to support AT innokin earlier. I have just discovered that Innokin has a dedicated forum here. The email that I composed earlier is quoted below.
I have a 134 mini, I have been using it for the past 6 or 7 months, and I am very happy with it. I have a few questions though. Should I charge a battery when the LED becomes RED, or should I keep using the device until the LED flashes RED and won't power the atty? Also, is the VW part available separately?