I ***SUSPECT*** that there might be something amiss with the problem battery. Something that might generate heat or back-voltage when it charges. I do not know what protective sensors or feedback might be built into the Apple batteries and charging circuits, so I am really shooting in the dark here. Maybe your errant battery has a short inside? Or, at the opposite extreme and even more likely, a break or corrosion (more impedance) in the internal circuit that interconnects the individual cells in the battery? Not much help, I know, --Steve At 4:23 PM +0000 3/11/06, Alex Hurst wrote: >I have two batteries. One charges up to 100% with no problem. The other goes to trickle charge after about 5 minutes whatever its state of charge. If you withdraw the battery for a minute and slide it back in, you'll get full charge for five minutes, then back to trickle charge again. I'm currently up to 84%, and appear to be advancing by about 1% for each time I repeat this procedure.