I have a 40 amp battery charger and 6 Trojan 6v batteries in series
parallel for one large bank.

I bought another identical 40 amp charger to install as a backup and
also extra charge capacity. My freezer is 1/2 hp 12 vdc - pulls about
30 amps so when running the genset at anchor to charge and freeze - I
could only net about 10 amps into the batteries as long as the freezer
was running.

Question - what will be the charge rate with both charging the
batteries and freezer operating. Should be 80-30 = 50 ?