[suicideneil]

Ah, I have that problem with the A123 cells too often. The voltage drops to a point where the charger (being thick) thinks it is only seeing a pack with 4 cells, rather than 5cells; or a 5s A123 pack rather than 6s in my case. What you need to do is set the charger for a 4s pack and charge it for about 10-15 minutes, then stop the charge. Now, reset the charger for a 5s pack and it should recognise all 5 cells- balance charging can now take place.