# Why are different currents used for charging batteries with the same voltage output?

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?

• Related to discharge rates: electronics.stackexchange.com/q/130580/2028 Oct 30 '14 at 21:25
• I would understand maximum discharge rates in the context of the current required by the load. E.g., a given load would want a certain current at the nominal battery voltage level. Therefore, as I understand, the battery would supply less voltage (and therefore less current) if the load would exceed the batteries ability. When charging, it would seem that charging at a given voltage would mean that the current is determined entirely by the battery's impedance, which is why I'm confused.
– John
Oct 30 '14 at 21:35
• That's why I am saying it's related. A battery that can supply higher current can also support higher charging current. Therefore, lower currents are used to charge batteries with lower capacities to avoid damaging them. The voltage used to charge batteries depends on the battery chemistry and charge level. Oct 30 '14 at 21:37