Got the pigtail I need and did a balance charge. It looked to me like the charger shut off before the cells were balanced. I use an orion Avionics charger and I had it set for 5a (1c). After about 30 minutes of charge I got an open circut error on the avionics. It didn't get to charge end like normal. I have the battery back on the balancer now. Any idea how long i should leave it on the balancer>? It was on at work for almost 8 hours today and it still reads as unbalanced.

Maybe learned the lesson of buying used batteries?