I'm trying to understand the behavior of batteries a bit more. I've noticed that chargers for given batteries have different current capabilities. Do batteries need to be charged with a voltage that is near their nominal output? E.g., a 12V battery should be charged with 12V? If one charger for a battery has a 1A output and the other has a 2A output, is the higher current charger actually just supplying a higher voltage?
The batteries don't have some kind of semi-conductor-like physics going on which allows them to maintain a constant voltage drop with different current levels, do they?