Necro charm mechanics

[Hyperstatic60]

I am wanting to get more into charming as a necro but it just seems so inconsistent. I can charm a mob 5+ levels below me and the charm commonly lasts less than a minute. This is hardly enough time to kill a mob with a charmed pet.

I've heard many things regarding the modifier for necro charm. Higher charisma, lower charisma, cha doesnt matter, higher int, MR check....the list goes on and on. I was hoping to get some opinions, ideas, or better, someone that has done experiments and knows something on the matter.

Thanks in advance.