How to Design a 42V-30V Battery Current Limiter With Selectable 2A/4A/6A Output?

Hello.

I want to design a current limiter for a battery powered project.

Battery will work at 42V when is fully charged and 30V when is discharged.

I want to limit the output current of the battery in 2 or 3 different values, depending the use, at 2 amps, 4 amps and 6 amps (with a potentiometer or different resistors).

Any help about which componets or integrated to use?. I have made some tests with mosfets, but the problem is the voltage changes between 42V and 30V and the current has not a fixed value when battery volatge changes.

Thanks for your time.

Hi
You can use a MOSFET to limit the current.
You can read the voltage using an ADC and a microcontroller.
The voltage has to be divided by a resistor divider, for a factor of 10, to be readable by the MCU.
Thand you can produce and PWM signal do drive the MOsfet, in series to the battery.
Cheers
Giovanni

You can get a rough idea from here too: https://www.pcbway.com/project/shareproject/Linear_power_supply.html
This power supply has adjustable overcurrent protection. which uses a potentiometer, a Hall-Effect sensor and an op-amp comparator.