Many FET drivers have a current sensing input pin for Amperage limitations. Switching power supplies have an impressive range of regulation possibilities with a much higher efficiency than "conventional" circuity. Add the battery as a buffer and you're good to go - Using a too weak power supply? The battery will simply discharge slowly instead of being charged.Well you could limit the current using a transistor and a resistor
If you're using a higher sensitivity than commonly used for overcurrent protection you can even actively approach the power limit of the power supply by monitoring the voltage drop. The controllers of switching power supplies already are monitoring the voltage drop on the output side to stabilize the voltage depending on the current load.