If you have voltwatch, perhaps it would be prudent to "measure" with both devices and compare what you get. Although the voltwatch does not give you a meter-like reading, you can compare green to green, yellow to your "no-mans land" and of course, red to red.

I see the voltmeter you have there has 4.9 and 9.6. The voltmeter should have a switch for RXbattery pack you are measuring too.. 4.8 / 6 volts.
Yours does not appear to be able to measure 6 volt packs.

CGr.