Yes I have. Does not help. Nor does the "switch DC-11 on first and then connect to N900" -method, or "Disable keypad lock first" -method...etc.

--> DC-11 just won't charge my N900 when battery is less than 50%. If battery is more than that (fuller) then it charges. I think it must have something to do with the expected power draw and "intelligent" negotiating loading mechanism (mentioned in many places in this forum, also in this thread).

--> Considering that "intelligence" I'm looking forward on software based fix to this BUG in the next firmware upgrade. I think, It shouldn't be a hardware issue and therefore short circuiting the USB-pins (mentioned elsewhere in this forum) should not be the solution to this case. I base my asumption to the fact that micro USB adapter provided along with N900 is not helping either when using it together with DC-11. I think the adapter should be "short circuited" if something, as it comes along with the N900 :-)

Summary: Only charger that is currently working with my N900 is the original AC-10E. Also other Nokia chargers are working when used with CA-146C Micro USB adapter, although I have noticed prolonged loading times as the output voltage varies between different Nokia chargers.

External battery (DC-11) is not working in any situation or with any method when N900 battery is lower than 50%.