Optical characterization sensing method of TFBG sensor for battery electromotive force monitoring

In the past few years, fiber optic sensors have demonstrated an amazing ability to detect the state of charge (SOC) and electromotive force (EMF) inside a battery in real-time. However, it remains an enormous challenge to characterize the relationship between the spectral shift of the fiber sensor and the internal EMF change of the battery. Here, we propose a method to monitor the electrolyte during the battery discharge process using the integral spectrum of a tiny tilted fiber Bragg grating (TFBG) sensor. The relationship between the fiber optic transmission spectrum and battery EMF was established by using this method. The results show that a TFBG sensor implanted in a lead-acid battery enables rapid EMF detection with a sensitivity of 1.16 × 10⁵ (nm·dBm) /V. This technology provides a fiber optic precision solution for battery operating conditions and has excellent potential for detecting battery failures using traditional EMF methods.