i have build a balancer for chests.
i use it together with the warehouse-mod because of the bigger sized chests.
it works also with normal sized chests.
Logic:
lower arithmetic combinator acts as a buffer.
middle arithmetic combinator forms the difference between the two inventories.
upper decider combinator sets the hysteresis. (set to at least 20 or the inserters will move items constantly between the inventories)
Balancer 1:
Blueprint Balancer 1
Balancer 2:For normal chests.
Blueprint Balancer 2
Balancer 3:Same as Nr.1 but with rotated combinators for more space
Blueprint Balancer 3
I think the design with normal chests could be improved but since i dont use this design, i didnt do any more research on this one.
Have fun