This might over-voltage your pack
I checked the cell voltages on a new 2S pack and pulled the pack off when the voltage had reached 4.25 v (on each cell) and the charger still had not cut off. 4.25v is already .05 over, so I didn't want to ruin a new pack. I don't have a convenient setup for checking where the charger cuts off. So be careful. It might over-voltage your pack and ruin it.
I give this product 2 stars. Review by Haselwood, Donald