I got a USB Car Adapter and when I plugged a Micro USB Cable in it it wouldn't charge the N900. :-(

When I use the PowerGuy Solar-Power Pack and connect it also with a Micro USB Cable the N900 won't charge. :-(

If I connect to the PowerGuy the old Nokia Connector then the Adapter for the Smaller Nokia Connector and THEN the Nokia Charging Adapter from the old Connector to Micro USB and THEN the whole thing in the N900... THEN it would sometimes charge. Sometimes not. After a couple of times plugging in and out it charges mostly for quite a while. (about 20 or 40 minutes, then it stops charging)
But the Nokia Charging Adapter (delivered with the N900) gets a little bit hot. Is this normal?

Not very nice the charging problem. In the best case the N900 should accept any kind of power (fron 1 to 40 Volt, AC or DC) on the Micro USB Port to charge the Battery. Only the natural instinct to keep alive!