I've now a couple of times tried the CA-146C adapter that came with the N900 (old round Nokia charger plug to MicroUSB) in my car with the Insmat phone charger I use for older Nokia phones. The light on the charger comes on, the N900 thinks it is getting juice, but the battery seems to be draining the same speed as if though there was no charger attached. And I have BatteryGraph data to prove it. A friend has had exactly the same experience with this adapter.

My N900 charges normally with the wall plug adapter, or via a MicroUSB cable from a computer, so it's unlikely this is a problem with the phone itself.

So, is the CA-146C just an decorative item with no real-world usability, are there a lot of defective units around, or what is going on here?