Balancing

[What's_nitro?]

Have you tried charging it on your friend's charger? At the full 1C rate? The pack should peak at the same 4.2V per cell no matter what brand of charger is used- unless the charger settings are incorrect or it's malfunctioning. If you don't need to charge anything over a 4s LiPo then I would go pick up a DTX Ice (or equivalent) charger. I've got two of them and they are probably the best for the money if you get them on sale. Another good choice would be the AstroFlight 109. It's completely automatic, but only works with LiPo cells.