No one has posted anything that I would call "authoritative" on this...
You could use another charger and the BB may appear to charge fine, but there's no way of knowing if anything bad is happening to your BB or battery in the long-term.
I'm not saying I know either way, I don't, but someone saying "Any charger works fine" isn't what I would call a sure thing that I'm comfy relying on.
If someone w/a professional background in this area can post why it's OK to use any charger w/a USB connector, that would make me more comfortable about using my mini-usb moto chargers w/my Pearl.
I did buy a Pearl car charger in the meantime...might end u p being a waste of $, but a few $ for no-worries was worth it to me at this point.