Batteries in Series Adapter

[JThiessen]

Update:
A week ago, I ordered an adaptor from MaxAmps, just to either rule out the one I made, or confirm it as the culprit.
I hooked up a pair of gp3300's, set it on autocycle, and it appears to function correctly. They charged up to 15.84V.
I tried the same with my IB4200's, but I'm still having problems with them. I think the charger is acting correctly. They will only charge up to 9.8V. I may have one of the infamous bad IB cells. Anyone have any tips or tricks to try to resurect a bad one? I'm currently trying to auto cycle them a couple times to see if that may help.

So it appears that even though my adaptor provided measurements that seemed correct, something was impedeing the electron flow - exactly why I became a Mechanical Engineer, not a Sparky!!