Originally Posted by burnineyes

Typically not a good idea, but if you keep your runtimes short you should not have a problem. If any of the cells are stronger than others and you run them to a low cutoff point, the stronger cells could show a total pack voltage high enough to keep running while "weaker" cells could fall below safe voltage. If you have the option to run a 3.6V or higher cutoff, that should keep all of them well above a safe voltage.