The R-26 is compatible with Alkaline (AA, LR6) and rechargeable Ni-MH (AA, HR6) battery types.
Note: Lithium batteries behave differently than other kinds of batteries and are not compatible with the R-26. Lithiums constantly have varying voltage effects and voltage levels. The results introduce the possibility of the Low Battery message not appearing when needed and, in worse case scenarios, the R-26 losing power without warning--recorded data may be lost in this case.