Originally Posted by def
The oilhead load shed relay turns on the low beam lamp when the key is turned to the run position. Then, when you operate the starter, the load shed relay extinguishes the lamp while you spin the starter. When the start button is released, the low beam lamp is repowered.
Unless you install some means of eliminating this hot re-strike when starting your BMW oilhead, your going to sacrifice some HID life.
I had that load shed issue on the LT so I installed a latching relay triggered by the high beams. The HID light stays off until I hit the high beams and the relay latches. On the 09 GS the head light never comes on until the engine is started. Must be an update to the ZFE module. It also goes off if the engine dies with the key on after 5 seconds.
Thanks for all the good info on the HID units.
I had experience building military trainers that used projectors with early HID bulbs in '97. Had an issue in that our design had the projectors moving through 80 degrees of movement and the bulbs were only lasting 30 - 60 hours (they were rated for 1000) and cost $580. Later found out the projectors had to be maintained level or near level or the arc would plate out material onto the quartz globe and they would heat up and shatter. Painfull and costly lesson.