but i don't know what you are using to charge with? genset? windgen? hydro?

i imagine each would have its own seperate concerns and how best to do it.

perhaps you could charge the whole lot together and only divide the strings for equalization periodically, that might be more practical.

there was a guy on ebay that sold some monster dc contactor/relays with 48volt coils
and 300amp capacity a while back, all new take outs made by prestolite.
the priceing was very good in my opinion, i got 4 of them in 24volt coil configurations for my system.

your probably going to need to divide the strings for charging  and certainly for equalization in my opinion.