I seem to remember the EPS needing to load it's OS from a disk when you turn it on , much like the Mirage sampler . If it does , there is no battery , no need for one . Since the EPS retains nothing after it's turned of , there is no need for a battery . As far as I can remember , I had a mirage , but it's been a long time since I dealt with an EPS . The Mirage , Emulator , Emulator II all had to load it's OS everytime it was turned on , they had no batteries . If the EPS functions the same way , it also has no need for a battery .