Does a battery charger limit current?
The current for charging a battery is a function of it Amp-Hour capacity (Ahr) and the battery chemistry.  Suppose you have a single 2.2 AHr cell, to the charge that battery in 1 hour, you needed 2.2 A.  We call this a batteries charge rate (C) which a metric for normalizing charging specifications.  In the example above, it was charged at 1C.  If we had two cells were in series, capacity for the pack is still 2.2 Ahr, and can be charged with 1C.  If the cells were in parallel, the capacity is now 4.4 Ahr, and 4.4 A is needed to charge them in 1 hour, but the charge rate is still 1C. You can now see why the charge rate metric was invented.

As for what charge rate to use... you can guesstimate by using other pack charge rates for common devices you use.  For example, a laptop, takes two hour to charge a 12Ahr pack, that is 0.5C, 6A. From this you can guess that its safe to charge this lithium ion pack at this rate rate.

Most batteries prefer constant current charging... However I have seen some lead acid batteries used in UPS systems that can take a constant voltage source.... However, I think everyone can agree that to maximize life of the cells you want to use a constant.

I have a little calculator I wrote that lets you play around with different charge currents, state of charge, and pack capacities.  The link is provided below.

http://onesolver.com/#!service=system_saved_load&amp;id=42&amp;tab=2