When does Change Battery LED Glow on IRD301 Vibration Meter?

When does Change Battery LED Glow on IRD301 Vibration Meter?

IRD301 is a simple Vibration Meter. It measures Vibration Velocity in mm/sec RMS. It runs on a single 9V battery that can be rechargeable type or non-rechargeable type. In ideal conditions - the battery should have 9V DC Potential - but with usage - the potential may drop to 8.3 V DC or lower.

Info
When IRD301 detects that the battery voltage has dropped to 8.3 V DC or lower - the Change Battery LED glows on the front face of the instrument - thereby indicating that the user should change battery.
Change Battery LED can be found near Middle Center of the Instrument