Lipo issue

[Jeremy1976]

Well I got my Rustler back together and had a chance to run the pack (Polyquest 2s 5000mah 30c) in it. It seems low on power in comparison to my SPC 2s 5000mah pack. However, the cells balance perfect and it charges just fine. What could be the possible cause? I am just shocked due to the fact this is a 30c pack and the SPC is a 15c pack. I bought the pack used from a reputable member on a forum. According to him he had about 6 cycles on it. I then put about 6 more on it. Always balance and charged on a Hyperion. He had a Duo and I have a net.