If this is a 5 cell type pac made from 2/3a or AA cells, I wouldn't charge it at over 1amp.

The 1C business is good with lipo (where it originated) and ok as a guideline for bigger sub c sized NiMhs, but for the smaller ones like 2/3a and AAs, fast charge at 1amp and slow charge at 0.5a. I slow charge mine as much as I can -they last a lot longer than way.