Heres the thing about electric winchs and batteries. While a small 2000-2500lb atv winch will pick up about anysize round you will come across, going with a bigger winch will reduce the amp draw on the battery. It all comes down to load. The closer the winch gets to max capacity the more amps it will pull from a battery and the quicker your battery will become dead. Also the closer the winch to max capacity, the slower the line speed. My splitter has a 25hp kholer with its standard charging system. I do have a marine grade full size battery on the machine. I have ran all day, draging 3-4ft dia rounds and have never had to wait on the battery. A 8000lb winch would certainy be overkill for firewood rounds, but a small stepup to a 4500lb winch will use less electricity than the 2500lb atv winch.
A bigger winch does not mean you will draw less current. Most of the time, it's just the opposite. I've looked at Warn winches and the bigger the winch the more it draws, unloaded. I saw some that were in the 60-80A range with no load, and they have way more pulling power than an atv winch. As you increase the load, yes the current will go up. One needs to look at the specs of the winch. Typically the faster the winch, the more current, but less pulling power you have.