I have the same three testers at 4-cell LiPo batteries in use - all three are working properly - point to 0.1 V at the same. The disconnectable and from 2.7V to 3.8V in 0.1V increments adjustable warning tone (apparently from two powerful piezoelectric pipits) is really noisy, appropriate for use with noisy aircraft as remote-controlled drones. When connecting the battery to sound the final control 2x .. As my examples come at Stromvesorgungen to a noise-sensitive film set to use, I was able to attenuate the volume dramatically, by letting in the two sounder few drops Alleskleber shrink (solvent-free). Now the warning tones are audible in quiet environments still good, but discreetly. The LED display changes continuously every second between voltage of each cell and the total voltage of the battery pack. The thus generated "anxiety" of the display also promotes attention - can be an advantage.
