Too many unknowns with your post to give you a good answer. At minimum we need to know your amp draw. What is the budget? What is the bar and what are you hoping to run on it? Is it dedicated for the one bar or something you want to run more than one off of?
I recently broke down and bought a good high amp regulated supply. Thing weighs about 50 pounds and has a fan. 70amp. It was not cheap but is is safe for strobes and LEDs but also powers even my biggest amp hog (XL9000 triple threat with 15 total sealed beams). I have a smaller 50 amp version too. Resist the urge to use battery chargers for anything other than the most rugged rotator bars. It is well worth the cost to just buy the right supply to start.