It's possible to use rechargeable (or Alkaline) batteries to power the TM-2. When using Ni-MH type AA size batteries, you can expect up to 6 hours of continuous use from the TM-2.
After installing them, be sure to change the Battery Type setting in the TM-2's System menu to "Ni-MH." Here's how:
1. Press and hold the SHIFT button, and then press the INST button. "[SETUP]' appears in the display.
2. Release the buttons, and then press the right arrow button (>) to select "SYSTEM."
3. Press the + button (ENTER).
4. Press the (>) button to select "SYSTEM BATTERY Type."
5. Press the + button to choose "Ni-MH" for the battery type.
6. Press the INST button twice when you're finished. The new setting is saved automatically.