I just thought I'd share in case anyone else has been using Orbtronic. In the past I never had any problems using them, and I have been using them for years. I recently picked up some cells for works in progress and found I could no longer solder to the button on the + end. Yes, I have tried roughing it up, flux, higher temp, etc, nothing worked. I believe they have switched to an alloy that resists soldering to intentionally prevent this. The website specifically says that you should not solder to the cell. (maybe it always did.)