I prefer the multiple packs to charging at the field. I bought 12 of the Hobby People 5s-4500 packs at $65 each. They may not be Thunder Power but they have very good performance at a very nice price. I'm seeing internal resistance numbers on the CellPro 10XP of around 2.1-2.3 per cell. I'll take that.

So I have 6 flights before I need to charge. That's about all the practice my brain can handle before I find I start to lose focus.