VGM-100 Battery Ground Fault & Voltage Dual Monitor

Model # VGM-100

The Eagle Eye VGM-100 Battery Voltage and Ground Fault Monitor is a combination ground fault and battery voltage monitor that reads battery status, detects out-of-limit conditions, and provides alarm indications at precise user settings for 24V, 48V, 125V and 250V systems. The VGM-100's status, adjustable under-voltage and over-voltage trip settings, ground fault, time delay (0-999 secs) and IP address settings are easily accessed on the user-friendly color touchscreen.

When the VGM-100 is installed & power is applied to the battery ground fault monitor, the firmware reads the stored settings and begins monitoring. Changing the stored settings, including the over and under voltage parameters & the ground fault conditions are easily done on the monitor's color touchscreen. If over or under voltage is detected, the voltage status will appear and the VGM-100 can activate a Form C contact. If a ground fault is detected, a positive or negative ground fault monitoring message will appear on the color touchscreen, and the VGM-100 will also activate another alarm contact. Modbus protocol output is also available on all units.

The unit is equipped with a total of four (4) Form C Output Contacts for alarm conditions - (1) for Under Voltage, (1) for Over Voltage, (1) for Positive Ground Fault Conditions, and (1) for Negative Ground Fault Conditions. The VGM-100 is extremely durable and easily installed as a wall, panel, or DIN rail unit.

Battery voltage monitoring will provide critical battery cell protection and ensure the longevity of the battery system. Overvoltage can lead to overcharging and overheating of the batteries, which can cause irreversible cell destruction. Under voltage will also cause irreversible battery damage if left uncorrected. Measuring battery voltage with the VGM-100 will allow the user to determine how charged their batteries are and allow for immediate corrective action if needed. Battery ground faults can be difficult to locate and may create catastrophic and costly damage if they remain undetected. The entire battery system will be compromised and subject itself to overheating, thermal runaway, and reduced battery capacity. Continuous ground fault and battery voltage monitoring will eliminate those risks, and allow for immediate corrective action to happen if a ground fault is located.

For effective and portable fault location, be sure to check out our GFL-1000 Battery Ground Fault Locator.

The VGM-100 Battery Voltage Monitor includes:

  • VGM-100 unit (for 24V, 48V, 125V or 250V)
  • DIN rail mounting clip
  • Backplate for wall mounting
  • User Manual

The VGM-100 is one of a family of digital monitors that read battery voltage and ground faults in a 24V, 48V, 125V or 250V system. Eagle Eye offers the GFM-100 Ground Fault Monitor to only monitor battery ground faults. Eagle Eye also offers the VM-100 which only monitors battery string voltage.

  • Specifications
  • FAQs
  • Benefits

Technical Specs

Measurement Range:Battery Voltage: 18-32, 38-60, 90-160, 180-320 VDC
Fault Resistance Limit Set: 1 – 100 kOhm
Fault Resistance Limit Set:1 – 100 kOhm
Output Contacts:(4) Form C
Contact Rating:125 VAC/VDC: 0.5A
30VDC: 2A
Maximum Switching Power:60 W
Power Requirements:Powered by connected battery DC voltage
Noise Immunity:IEEE/ANSI Standard C 37.90a-1989 compliance
Time Delay to Alarm:Adjustable 1 – 999 seconds
Operating Environment:Temp: 0 – 55°C (32 – 131°F), Humidity: 0 – 95% RH
Dimensions / Weight:147 x 91 x 45 mm (5.77 x 3.56 x 1.77 in) / 284 g (10 oz)


What are some common applications areas for this product?
Common applications include but are not limited to:

  • Power Utilities
  • Telecommunications
  • CATV / Broadband
  • Mission Critical Facilities
  • UPS Systems
  • Power Generation & Distribution
  • Financial Institutions
  • Oil, Gas & Fuel & Petrochemical Operations
  • Mining
  • Government/Defense
  • Transportation Operations
  • Hospitals
  • Emergency Lighting
  • Green Energy
  • Call Centers
  • Battery Suppliers and Manufacturers
  • Battery Service Groups
  • Medical/Biotechnology

How does the VGM-100 detect ground fault conditions?
DC ground fault detection is determined by measurement of the voltage imbalance relative to ground. These measurements are made through very high resistance divider networks. One establishes the ground reference, and the other measures the positive and negative DC voltages. These values are applied to analog-to-digital converters, and the microcontroller firmware compares the sum of these DC values to the ground reference. If the sum is 0, the DC voltage is perfectly balanced relative to ground. If the sum is positive or negative, the DC voltage is unbalanced positive or negative. User settings determine the extent of imbalance that will result in an alarm condition.

Will the VGM detect a ground fault via a leaked battery jar?
The system would detect a ground fault via a leaked battery provided the ground fault resistance setting (a user setting) was set to the proper value. Since a leaking jar would result in a path to ground of some resistance, the VGM would sense the resulting voltage imbalance and would alarm, provided the path to ground created by the leak was of a resistance lower than that setting.

What is the k ohm limit for ground detection?
Up to 300k ohm.

What is are the contact ratings for the Form C contacts?
The relays have a contact rating of 60W, with a maximum voltage rating of 220VDC, and a maximum current rating of 2A. With these ratings, this relay can switch 2A at 30VDC or less, 0.5A at 125VDC, but only 0.009A at 220 VDC. An external relay would be needed if the customer wanted to increase the rating past the limit.

Do the connections between the monitor and the batteries need to be fused?
No, the monitor has a built in fuse to protect the monitor. However, you may want to fuse the connections to protect against the possibility of a short circuit occurring in the wiring to the monitor.

Is the VGM-100 CSA certified?
The VGM-100 Battery Ground Fault & Voltage Monitor is CE certified. For Canadian customers, CSA certification is not required on DC powered units. Please contact Eagle Eye with any questions on certification requirements.


  • Monitors for Battery Ground Faults & Voltage in 24V, 48V, 125V, & 250V batteries
  • Color touchscreen simple interface
  • Ethernet connectivity to web interface or Modbus protocol
  • (4) Form C Contacts
  • High reliability & durability
  • Simple installation with mounting kit for DIN rail or wall mount
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  • Model #

    Battery Ground Fault & Voltage Dual Monitor, available for 24V, 48V, 125V, or 250V

    Determine part number for required voltage, Ex. VGM-100-XXX would be VGM-100-250 for 250V applications.

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