your asking a question that cannot be simply answered with any precision
how much amperage is being delivered to the charger? that will depend on how much load there is on the charger, for instance
if the charger is 120volt input
and you are putting out 30 volts and 20amps
take the 30volts x 20amps =600watts
600watts/120volts = 5amps
so in this example the quick and dirty answer is 5amps input at 120volts gives you 30volts at 20amps output, but
that is an idealized scheme and nothing in the real world comes out like that, there are problems starting with power factor on the AC side, inverter/charger efficiency, and other losses, so
the reality might be as much as 10amps at 120vac to get 30vdc at 20amps output, and if the power factor is really bad it might be worse.
might be easier for you to get some idea by just getting a moderately priced clampon meter and just do some checking, even a cheap one will give you better numbers than you are going to be able to calculate given all the variables and unknowns in the system.
as far as max into the battery bank, that is a moving target, as the battery bank charges its ability to take in power drops off, or rather your charger will taper back the amperage. here a meter would be most useful if you wanna know what is going into the batteries.
don't know if this answers your questions or not, but i tried
bob g