HOW CAN I MAINTAIN HIGH CURRENT IN NEGATIVE DC TO DC REGULATOR?

[Philenius]

I have a project to design a negative DC regulator.
I have a batter of 48Vdc with 50ah so I want to regulate the voltage from -48vdc to -12vdc without affecting the current of 50ah. Please I need help anyone help me a diagram of that circuit or which is relating to my project or a advice. Remember am stepping down negative voltage.

 

[Reloadron]

I'm wondering if the tower generator has a diesel engine to run the generator, but also a big battery to keep some or all of the lights going for some time without the engine running. There would also be a 12 V battery to start the diesel engine.

These things are what I always called a "light tower". I wanted to associate "tower generator" with a wind turbine. Guessing now I got that wrong.

Ron