How many amps in a 1500mah battery?

A 1500mAh (milliamp-hour) battery can provide a current of 1.5 amps for one hour. To convert milliamp-hours to amps, you divide the capacity by 1000. Therefore, if you use the entire capacity over one hour, it can deliver 1.5 amps continuously. If the usage time changes, the current will adjust accordingly.