Hi there!
This link might help you: **broken link removed**
With current-limiting resistors for each leg of the array, the calculator figures the array pulls 560mA, or 0.56 amps. I think you should be using the resistors so you know the current limit for the diode strings. Somebody who knows more about this, please jump in if I'm wrong on that.
I don't think you'll get much run time (maybe a couple of hours) off your battery. Its voltage will drop somewhat as it loses charge; how quickly it drops and when it starts to drop depends on the kind of rechargeable is it (NiCad, NiMH, LIon, etc.). Googling for "rechargeable battery discharge rate" or similar terms might help figure it out for your battery, though.
I know this isn't a lot of info, but I hope it helps.
Torben