deilenberger
A bozo on the bus
Robert -
As has been suggested - likely the best way to do that is to switch to 35W ballasts (the bulbs probably don't need to be changed..)
I don't have a ZFE power output diagram handy - but for the dual low beams on the RT, it would make sense for BMW to have a separate output circuit (and solid-state switch) for EACH bulb, so if one fails (say by something ugly like shorting out) the other bulb could remain operational.
If so - it sounds as if these ballasts draw too much current - and the current shutdown threshold on the two outputs may be very slightly different - so one output thinks there is a short of some type and shuts down the circuit. The problem is likely the startup current - the circuit may be quite happy with a "running" draw of 55W, but with the additional current drawn as the bulb is "ignited" (perhaps an additional 15-20W based on car ones I've used) - it might be pushed over the shutdown threshold. The 35W rated one (drawing 35W after ignition is complete) - even if it draws 55W on startup/ignition - won't be over the high-current shutdown threshold.
As has been suggested - likely the best way to do that is to switch to 35W ballasts (the bulbs probably don't need to be changed..)
I don't have a ZFE power output diagram handy - but for the dual low beams on the RT, it would make sense for BMW to have a separate output circuit (and solid-state switch) for EACH bulb, so if one fails (say by something ugly like shorting out) the other bulb could remain operational.
If so - it sounds as if these ballasts draw too much current - and the current shutdown threshold on the two outputs may be very slightly different - so one output thinks there is a short of some type and shuts down the circuit. The problem is likely the startup current - the circuit may be quite happy with a "running" draw of 55W, but with the additional current drawn as the bulb is "ignited" (perhaps an additional 15-20W based on car ones I've used) - it might be pushed over the shutdown threshold. The 35W rated one (drawing 35W after ignition is complete) - even if it draws 55W on startup/ignition - won't be over the high-current shutdown threshold.