I have a couple of Bizpower battery packs, featuring 5V 1.5A output on an USB female connector (only VCC and GND pins). In the last months I used them to charge some portable devices (which had an USB plug for charging). While it may sound strange, sometimes it has some sense charging a battery using another battery. For example - as in my case this week - when you are going to have a few days trip without any AC power plug all the way. I just found that N900 does not start charging until some USB event happens. That is, it doesn't charge when applying the CA101 USB cable to the above described "5V battery with USB plug". And the N900 doesn't charge when applying the CA101 to my notebook in standby mode (while in standby mode, the notebooks keeps the USB power up, but the charging only starts when the notebook is running). It only charges when there is some of its official cables/chargers. This is quite annoying. The quickest solution is to buy immediately another BL5J battery for the N900, and/or stop playing games, stop listening MP3s, stop watching videos, stop phone calls, stop browsing the network, stop, stop, stop... and crossing my fingers, hope to last three-four days.