I tried to run my 5W with 6AA (sometime 7AA) rechargeable battery and somehow I can get a variety of range, from 650 to 2 A. As soon as I got something above 1.5A, i immediately turn it off. So, i guess i ran my 5W at 2A only for a few seconds. But like most said, if you got a great heatsinking, 1.5A is still of no problem.