I have one of the earlier usb charging cables, and i notice that i have no problem charging the original batteries, the ones with the brass coloured thread, but when i charge the new ones, with the silver thread, I find i have to wipe the tread with a damp cloth, also the inside thread of the charger, it's not a big deal, but i was wondering if anyone has had a problem with the small usb charger that they supply now ? I was thinking it may be an idea to get one of those. Also anyone notice how the design of the larger carts tend to leak into your mouth more so than the smaller ones?