If that device is the same as the voltwatch2, it hooks up to a vacant or Y connected port on the receiver. It monitors the voltage once the "system" is powered on.

The flickering LED's indicate usage. Flickering to the yellow is norma. Going to the red may... MAY... indicate that you have a binding linkage.

Operate the controls one at a time to exercise one servo at a time and see what one is causing it to go to the red. Then, look closely at that linkage to see what may be causing the bind. Throttle is usually the culprit, so look at that closely for end points so that, when going to full open or full closed, the servo is not trying to force the control beyond it's physical (mechanical) limit.

If no obvious binds exist, then you may... may.. have a weak battery.

I use, pretty much exculsively, 5 cell (6 volt) packs, about 20% higher capacity than your 4 cell packs, typically at least 1200 mah.

Try that out and let us know how it works out.

CGr.