I am realizing, reluctantly, that this whole flashlight and battery interest is fast becoming a monkey on my back. So I think I need a way of measuring the charge of my batteries. Is this what a voltage meter does? Does it just measure a cell's voltage, such as 1.2 V, etc.? Does it also measure the Mah level? You can probably tell right away that I have an electrical engineering degree from MIT.
I don't want to spend a lot of money, which to me means not over $25. I'd be grateful for suggestions.