If you do the math, and use the equation P=I*E(p=power in watts, I current, E voltage) then assume its charging at 4.2volts per cell, and replace P with 50 watts it would be Charge rate=50/(4.2*the cell amount)

2.3A for the 5S
3 amps for the 4S

Note it might time out at those settings as it was said earlier some charges time out after awhile, and need to be restarted.

Personally I'd get a 100watt charger for batteries of that size so they can be charged at 1S in an hour cause at those ratings it will take like 2.5 hours for the 5S to charge, and 1.5 for the 4S

NiMh is fine at 4.6A that should be an hour if it don't false peak. NiMh's are more of a trial and error thing as if it doesn't false peak, and sits about an hour on the charger it is fine, but if it false peaks you will have to lower it a lil at a time till you find a rate it fully charges at