I'm using the Deutronic DBL-800, as the one in BMW dealer. It's quite nice to charge or supply correct voltage when programming/coding. As I know, 14.8V is the specific voltage when programming/coding the BMW cars.
DBL-800
http://deutronic.com/battery-chargers/800-watt.htm
DBL-800 IP
http://deutronic.com/battery-charger...att-mobile.htm