Is there a setting to make the LED flash for PWR mode and not have them flash while on the batteries?
No.
The only battery vs. external power setting ("LModeBAT" and "LModeEXT") affects all lights. You could set "LModeBAT" to "Stlth" and that would keep the tri-color LED turned off, but then you wouldn't get the backlights, either.
No, there's no way to turn off just the tri-color LED - apart from creating a separate V-Scanner folder that has it turned off (for each object).
No.
The only battery vs. external power setting ("LModeBAT" and "LModeEXT") affects all lights. You could set "LModeBAT" to "Stlth" and that would keep the tri-color LED turned off, but then you wouldn't get the backlights, either.
I love the backlight on and LED flahing when on a wall charger but found out these settings were unacceptable for battery life. Now I have the best of both worlds.
If you set "LiteLevel" to "Low", the various LEDs won't significantly impact battery life. They'll only draw about 6mA total (LCD backlight on, keypad backlight on, tri-color LED "white").