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Battery State-of-Charge Sensors

Battery State-of-Charge Sensors

Refractometry for
SOC Sensing

SOC Application
Data 07/12/2019

The Problem


Existing solutions to measure state of charge rely on labor intensive measurements of cell specific gravity or inaccurate voltage or charge bookkeeping methods. This device is a convenient, accurate, and inexpensive solution for real-time direct measurement of the state-of-charge of lead-acid battery cells critical in many emergency power, motive power, automotive, and telecommunications applications. 


The Solution


This patented solution is based on fiber optic sensing technology originally developed at one of the nation’s national laboratories. The device effectively measures cell specific gravity the historical standard of battery charge levels and enables inexpensive, accurate, and continuous monitoring of battery capacity.



The Product

This technology can be easily retrofitted to existing batteries or even incorporated during manufacture, thus providing built-in functional assurance and reduced maintenance costs to the user.

The SOC sensor offers additional benefits well beyond specific gravity determination:
  • The sensor can be powered from the battery itself.
  • An internal temperature sensing element provides additional information on cell conditions.
  • An alternate version of the sensor provides independent electrolyte level measurement.
  • Additional software enables automatic and continuous monitoring of battery conditions for one to several thousand batteries on-site, or over the Internet.
  • The best news is all of this can be attained at a cost less than a good quality voltmeter.
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