"and added a 200A Circuit breaker to each battery
Are you aware that even a car's Group 24 SLI wet lead battery can put 3000A into a crowbar short? So that a conventional 200A circuit breaker, even on your car, would actually arc
weld itself shut and then FAIL TO OPEN and a crowbar short would become a fire.
I can't help thinking that a lithium battery must be able to put more amps into a crowbar short than a car battery...which is why proper breakers with the ability to withstand huge shorts, of better yet battery fuses
, are usually recommended.
Forgive me if that's old news, but when I found out why breakers were only good for "secondary" protection, I was kinda amazed too.