On the topic of charging: A simple way to do it would be to use a
transformer that, when rectified and filtered, has ~5v higher voltage than the max voltage of the pack you are using, set up a constant current charge circuit (pretty simple), and then use a comparator IC that shuts off the charger at 3.6v/cell. It won't have the CV charge phase, but from what people say, very little charge is done at that point anyway.
So, if you are running 14s packs, that's 50.4v. Add 5v (to account for current source dropout) for 55v. The Y23695 3 in the link above would be ideal; wire the primaries in parallel and the secondaries in parallel, use bridge rectification, around 0.5F capacitance (can use an inexpensive car audio cap). The 40v AC output would be around 56v once rectified and filtered, and would provide over 10A charge rate. Add the CC source and cutoff circuits and be done with it. Balancing, if desired, can be done using multiple balancers, just overlap a cell on each so they are in sync.
Of course, this doesn't have cell count protection, but since it will be used just for a single application, it's fine.