I think I shorted that first battery badly on the minus terminal, I may have left it at an angle, shorted and that's why it died completely. It's at 1.9v and won't power a module on at all. I noticed because I took one out to test it and the voltage…
Thanks for the quick reply and for the hints! I finally got some time to get my modules together, so I hope to have a look at your code sometime soon. When I get going, I'll post my progress