I agree with bigtim. soldering battery cells together is a very critical task and uless it's done properly you could easily ruin a cell. unless you are very good at soldering you might want to consider buying prebuilt packs. The seal on a battery cell is very thin plastic and if you heat it too long it will melt the seal and the battery will be ruined. And what is too long?? 2 secs is really too long. Once that seal is ruined the cell is no good. While it may look like it will hold a charge after the seal is shot, it's a false reading as the battery can fail at any time now. With the low cost of packs now it's easier to simply buy a pack already built.

Ken</p>