The times given are for turn on till shutdown (failure) of the respective transmitter. Times on alkaline AA's will drop greatly if the batteries are below room temperature. These times are typical and not guaranteed. Also note that the batteries were fresh and in excellent shape.
The SM or MM transmitter will operate for slightly less than 2 hours on one Eveready or Panasonic alkaline AA battery, for 4 hours and 5 minutes on an Eveready 2200 mAh NiMh battery and for 6 hours and 30 minutes on an Eveready lithium battery.
The SMd dual battery 100 mW transmitter will operate for slightly less than 6 hours on two Eveready or Panasonic alkaline AA batteries, for 8 hours and 30 minutes on two Eveready 2200 mAh NiMh batteries and for more than 14 hours on two Eveready lithium batteries.
The SMq dual battery 250 mW transmitter will operate for slightly less than 2 hours on two Eveready or Panasonic alkaline AA batteries, for 5 hours on two Eveready 2200 mAh NiMh batteries and for 7 1/2 hour on two Eveready lithiums.
The variable power SMv transmitter will operate at 50 mW for 2 hours on an alkaline AA, for 4:45 on a 2200mAh NiMh AA, and for 7:20 on an Eveready lithium AA.
The variable power SMqv dual battery transmitter will operate at 50 mW for 5:50 hours on two alkaline AA's, for 9 hours on two 2200mAh NiMh AA's, and for 14:40 on two Eveready lithium AA's.
Your mileage may vary, See FAQ#087-WIRELESS.