Sennheiser SK250 with three AA batteries.

The graph below shows the comparative battery life of various AA batteries in a SK250 body pack transmitter.

The SK250 graph cuts off at 2.5 volts which is where the transmitter stops operating. The lines at 3.6 and 2.8 volts show where the battery sled indication changes from high to medium and medium to low respectively. The lithium batteries lasted between 30 minutes and 2 hours longer than the alkaline batteries.

Pleae note that the same transmitter was not used for each of the tests shown above.