The old 2mm Nokia chargers output some 6.5V - 7V, or atleast all mine do. The charging chip in n900 isn't able to use such high voltage. The adapter has a DC-DC converter that steps down the voltage. It's quite inefficient at what it does, less than 70% with my N810 charger (6.8V, 850mA), so it's no wonder it gets hot when it's eating over 1W for itself.

Oh thank goodness for this thread!
i actually thought it was the phone itself, sounds a bit like the hdd in laptop spinning up.
then tonight i realised it wasnt central to my hearing and worked out it was the charger.
well i have a weird phobia of electricity so panicked and found this thread fortunately.

doesn't seem to be much conclusion but at least i know its standard.

sorry for lack of caps and things .. dislocated knuckles, cant hold down two buttons at once.


nicola