I can’t say why lead-acid batteries don’t require balancing internally.Weird. The moderators over on solar panel talk say the opposite.
Why don't normal 12v batteries or 24v cat batteries have the out of balance issue among cells?
I also thought that's why you were supposed to use 2 6v golf cart batteries on your rvs instead of two 12v?
I don't know anymore....I have 3 8d 12v batteries parallel in my system and they have been thus far.
But batteries in series will always stray out of balance (slowly). To minimize stray, you want to match leads from both batteries as well as practical (match resistance).