ELM-Series Battery Electrolyte Level Monitor

Model # ELM-Series

The Eagle Eye ELM-Series Battery Electrolyte Level Monitor is a reliable dual sensor system that monitors the electrolyte level and temperature of individual flooded batteries. Utilizing low-cost, easy to install sensors, the system will alarm on low electrolyte level or higher than normal temperature. The sensors are simply and securely attached, either directly to the battery jar, or via an optional clip which allows the sensor to be removed and re-used if the cell should require replacement. The ELM-Series battery electrolyte level monitor and sensor is customized to work for any flooded battery system. Each battery system receives (1) ELM-Monitor and the number of sensors per cell.

The ELM-Series battery electrolyte level monitor is commonly used in the power utilities market. The ELM-Series will comply with NERC PRC-005-2 guidelines that require electrolyte level monitoring. When the ELM-Series is integrated with Eagle Eye's stationary battery monitoring systems NERC PRC-005-2 compliance will be met. To learn more about NERC Compliance Solutions and our battery training courses please Contact Us today!

  • Specifications
  • FAQs
  • Benefits
  • More Info

Technical Specs

Battery Types:Compatible with all transparent flooded battery types
Temperature Alarm Activation:35 °C (95 °F), ± 2 °C (3.5 °F)
49 °C (120 °F), ± 2 °C (3.5 °F)
63 °C (145 °F), ± 2 °C (3.5 °F)
Optional: No temperature alarm
Level Accuracy:±2 mm (± 0.08”) above or below line label
Input Voltage:12 VDC, AC/DC wall adapter included standard
Additional voltage inputs available with optional PSU
Output RelaysSPDT volt-free contact relays for:
1+ low electrolyte level detection
4+ low electrolyte level detection
1+ high temperature detection
4+ high temperature detection
(L x W x D)
Monitor: 176 x 80 x 51 mm (6.9 x 1.6 x 3 in.)
Sensor: 54 x 35 x 15 mm (2.2 x 1.4 x 0.8 in.)
Sensor Cradle: 65 x 52 x 14 mm (2.6 x 2.1 x 0.6 in.)
Cables: 1.25mm pitch at length of 305 mm (12 in.)
Weight:ELM Monitor: 210g (7.41oz)


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
  • Generation & Distribution
  • Financial Institutions
  • Oil, Gas & Fuel
  • Mining
  • Government/Defense
  • Transportation Operations
  • Hospitals
  • Emergency Lighting
  • Green Energy
  • Call Centers
  • Battery Suppliers and Manufacturers
  • Battery Service Groups
  • Medical/Biotechnology
  • Generators

How does the ELM monitor temperature?
The electrolyte level monitor uses a high sensitivity temperature IC mounted in the case.

How does the ELM monitor battery electrolyte?

What cleaning is required on the battery cells before installing the ELM system?
Each ELM kit includes (1) roll of cleaning towels and (1) can of CRC PF Precision Cleaner. It is essential to clean the cells with the included cleaning kit to prevent the sensors from falling of the cells. One cleaning towel should be used to clean no more than (4) cells and one can of cleaning spray is good for up to 240 cells.

Is there an audible alarm available for the ELM?
The ELM does not include an audible alarm but it is possible to use an external one. The contacts on the warning outputs are completely isolated from each other and the sensor circuits, therefor you can drive any circuit with them, lights, audible alarms, motors, pumps etc. The contacts are rated at 15 amps for 125 VAC or 10 amps at 277 VAC. There is a rating of 2KV between the contacts and coil (the coil is connected to the sensor circuits).

How are the electrolyte level and temperature alarms reset?
An electrolyte level alarm occurs if low level electrolyte is detected for more than 40 minutes (to prevent spontaneous alarming). When a level alarm is active, it will remain so until the electrolyte level is restored and the R/S button is manually pressed on the sensor. The temperature alarm occurs as soon as the threshold temperature is detected, it will reset automatically after 4 minutes.

What are the guidelines for mounting the sensor?
The electrolyte level sensor must be mounted vertically in the upright position. It must be flat on the surface of the jar with the “level” line on the sensor in line with the “minimum” line on the jar.

What are the minimum clearances around the sensors on the battery?
The clearances are based on distance above and below the “minimum” line on the battery jar. The sensor frame can be removed to decrease the required clearances. Minimum height without frame: 29 mm (1 1/8th") Typical height with frame: 35 mm (1 3/8th") Minimum depth: 32 mm (1 1/4").

Will the adhesive tape used to mount the sensor cause deterioration to the battery jar?
The adhesive tape included on the sensors and cradles has been thoroughly tested and will not damage the battery jar.

What is the power consumption of the ELM?
Power consumption depends on the number of sensors connected and the number of faults detected. The monitor consumes 0.36 watts; a single sensor consumes 0.024 watts with no faults. The total power consumption for common system configurations with no faults would be:

  • 60-cell system: 0.36W + (60 * 0.024) = 1.44W
  • 120-cell system: 0.36W + (120 * 0.024) = 2.88W
  • 240-cell system: 0.36W + (240 * 0.024) = 5.76W
The peak power consumption with 4+ Level & Temperature faults would increase the monitor to 1.44W:
  • 60-cell system: 1.44W + (60 * 0.024) = 2.88W max
  • 120-cell system: 1.44W + (120 * 0.024) = 4.32W max
  • 240-cell system: 1.44W + (240 * 0.024) = 7.2W max

What is the power requirement per sensor?
One Monitor and one sensor would require no more than 0.1 amps at 12 volts.


  • Low cost monitor for electrolyte level & jar temperature monitoring
  • Alarm contacts for external alarming
  • LED lights on monitor and sensors for visual alarming on-site
  • Easy to install, site survey not required for order
  • Applicable to any flooded battery system regardless of voltage & amp-hour
  • Utilized commonly available cabling between sensors for easy sourcing of additional materials

More Info

In the condition of a low electrolyte or temperature alarm, the sensors communicate to the system monitor and the system monitor activates a changeover relay output while simultaneously activating the appropriate alarm LED lights. The LED light will indicate either 'low electrolyte level' or 'cell over-temperature'. In the event that four or more cells fall to an alarm level, the monitor will trigger a group alarm in addition to the single cell alarm. The alarm contacts are volt-free and can be made as ‘make-on-alarm’ or ‘fail-safe’ mode (giving warning of a supply failure) and may be linked in to any facilities management or alarm system for remote battery monitoring.

LED Indicators For:

  • 1-3+ Cells Low Level
  • 4+ Cells Low Level
  • 1-3+ Cells Critical Temperature
  • 4+ Cells Critical Temperature
  • Power Failure

The ELM-Series Electrolyte Level Monitor is an easy-to-install battery temperature monitoring solution. The non-invasive system is applicable to any flooded battery system regardless of voltage and amp-hour. The ELM-Series utilizes commonly available cabling between sensors - allowing easy sourcing of additional materials. The battery electrolyte level monitoring system saves time & money by continuously monitoring electrolyte levels and eliminating the need for scheduled periodic testing & maintenance. Markets that use lead-acid batteries have to perform periodic testing to ensure the battery's life. Hydrometers are one of the most common testing methods - but they can be time-consuming and allow possibilities for errors and safety risks. The ELM-Series is a real-time solution for monitoring battery electrolyte and temperature levels - allowing 24/7 protection.

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  • Model #

    Battery Electrolyte Level Monitor: includes (1) Monitor and number of sensors per cells

    Model number varies per number of cells (Ex. ELM-60C for system with 60 cells)

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Companies We Serve
  • OG&E: Battery Electrolyte TestingATT Logo: Battery Electrolyte Testing
  • Duke Energy: Battery Monitoring Systems Cenovus Energy: Battery Monitoring and Electrolyte level monitoring
  • SMUD: Electrolyte Monitoring American Electric Power: Battery Testing