Well, with powered holder battery capacity doesn't matter that much.
Some time ago (this spring) I read a
thread on a correct car charger for Axims - the one that was able to charge the PDA while it is on. As far as I remember, the problem with most of the noname chargers is that they use wrong pins to supply power (they use USB sync/charge pinout and not DC-in pinout), and they are not powerful enough to fully charge a battery.
So, do you know, by chance, if this one can charge the PDA while it is
on?