Just to be clear, I'm not suggesting taking the lipos apart but breaking away the tape that bounds the cells into a pack so that individual cells can be accessed.
It's actually a common problem with cheap batteries where the cells hold different charges when bought. When you charge a cell pack, you are always over charging some cells and/or under charging others. This is why some brands are so expensive. They take batch of 1000 cells and test charge and drain them and selects cells with similar capacity, charge/discharge rate and make them into packs.