I assume it takes AA size batteries. 1.5V is typical for single use types, but they can drop as low as 1V or less over their working life. Rechargeables (NiCd or NiMH) are nominally 1.2V but drop relatively slowly, so you can get a decent working life out of them too.
If it helps, I have the Sigma ringflash and it runs happily off a set of NiMH batteries.
_________________Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 70-300L, 100-400L, 100L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.