The test result of power consumption based on Minolta's standard test method is approximately 200 images per set of Ni-MH batteries. DiMAGE 7 controls power level strictly as it processes vast amount of data at once, easily effected by even a small factor. For instance, stain on the terminals of battery may change power consumption rate. Please try to wipe the terminals of each battery with a dry cloth strongly before use.
Generally the performance of Ni-MH (Nickel Halide) battery cells may lessen if those are re-charged repeatedly without making full-use. Please discharge them fully before re-charging.