I would guess, as Rick did, it's three 3.7V cells in series, with a duplicate set in parallel, or a series of three sets of two parallel cells. You could have any one of a large handful of cell types, but it's most likely (don't take my word if you do any charging - find the actual specs) that you have six 2200mAh 18650 / 186A size cells in that series parallel arrangement.
Regardless, you'll need more than a single chip solution. I've used the MCP73831 chip and I really like it, but it's a single cell device. What you have would require something more complex than that.What does the battery pack come from?
