I can only find CR3032 coin cell. Which is 10mm x 3.2mm. But it is 3 volt not 1.5 volt. 500mah. (where did you find a 1.5 volt coin battery?)Oh and the batery can be no bigger than 10mm x 3mm.
three 3volt fans
Just for the 3 fans we need 100 to 300ma.36 mA to 97 mA