Did you get them used? If so, you have no way of telling how many cycles they have on them. You really don't know if they are out of balance or not.

You can just plug the packs into a charger and charge them up. I don't own any of those packs, because I find them to be a PITA to tend to, so I don't want to assume anything and advise of you how to check the voltage of each cell before you charge them.

Perhaps someone that does own them can comment.

I suspect that the little hole in the pack taps into the series connection between the two cells. If this is true, then you should be able to get a reading on each cell by using a dmm and using the probes on the + connection and the center tap for one cell and then the center tap and - connection for the other. Please get confirmation on this before you do anything.