{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T07:37:49Z","timestamp":1770277069463,"version":"3.49.0"},"reference-count":31,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2010,3,25]],"date-time":"2010-03-25T00:00:00Z","timestamp":1269475200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This article describes a multi-point optical fiber-based sensor for the measurement of electrolyte density in lead-acid batteries. It is known that the battery charging process creates stratification, due to the different densities of sulphuric acid and water. In order to study this process, density measurements should be obtained at different depths. The sensor we describe in this paper, unlike traditional sensors, consists of several measurement points, allowing density measurements at different depths inside the battery. The obtained set of measurements helps in determining the charge (SoC) and state of health (SoH) of the battery.<\/jats:p>","DOI":"10.3390\/s100402587","type":"journal-article","created":{"date-parts":[[2010,3,25]],"date-time":"2010-03-25T12:20:28Z","timestamp":1269519628000},"page":"2587-2608","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["A Multi-Point Sensor Based on Optical Fiber for the Measurement of Electrolyte Density in Lead-Acid Batteries"],"prefix":"10.3390","volume":"10","author":[{"given":"Ana M.","family":"Cao-Paz","sequence":"first","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Jorge","family":"Marcos-Acevedo","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Alfredo","family":"Del R\u00edo-V\u00e1zquez","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Carlos","family":"Mart\u00ednez-Pe\u00f1alver","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Alfonso","family":"Lago-Ferreiro","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Andr\u00e9s A.","family":"Nogueiras-Mel\u00e9ndez","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]},{"given":"Jes\u00fas","family":"Doval-Gandoy","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, University of Vigo, 36310 Vigo, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2010,3,25]]},"reference":[{"key":"ref_1","unstructured":"Rand, D.A.J., Moseley, P.T., Garche, J., and Parker, C.D. (2004). Valve-Regulated Lead-Acid Batteries, Elsevier."},{"key":"ref_2","unstructured":"Linden, D., and Reddy, T. (2002). Handbook of Batteries, McGraw-Hill. [3rd ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/S0378-7753(01)00560-2","article-title":"Methods for state-of-charge determination and their applications","volume":"96","author":"Piller","year":"2001","journal-title":"J. Power Sources"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1509","DOI":"10.1143\/JJAP.21.1509","article-title":"Optical fiber sensor for measuring refractive Index","volume":"21","author":"Takeo","year":"1982","journal-title":"Jpn. J. Appl. Phys"},{"key":"ref_5","unstructured":"San Martin, J.I, Achaerandio, M., Gaston, A., and Sevilla, J. (1998, January September). Desarrollo de sensores de \u00edndice de refracci\u00f3n de l\u00edquidos basados en fibra \u00f3ptica pulida lateralmente. Pamplona, Spain."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1053","DOI":"10.1109\/19.199390","article-title":"The measurement of the relative density of homogeneous fluids by means of an optical technique","volume":"41","author":"Hancke","year":"1992","journal-title":"IEEE Trans. Instrum. Meas"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1016\/S0925-4005(04)00424-1","article-title":"A sensor of sulfuric acid specific gravity for lead-acid batteries","volume":"105","author":"Guo","year":"2005","journal-title":"Sens. Actuat. B"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1109\/T-SU.1983.31389","article-title":"Development of an ultrasonic technique to measure specific gravity in lead-acid battery electrolyte","volume":"30","author":"Swoboda","year":"1983","journal-title":"IEEE Trans. Son. Ultrason"},{"key":"ref_9","unstructured":"Gayol, A., Marcos, J., N\u00f3voa, R., Pe\u00f1alver, C.M., and P\u00e9rez, M.C. (2001, January October). Resistivity measurements in lead-acid batteries. Berlin, Germany."},{"key":"ref_10","unstructured":"Dakin, J., and Culshaw, B. (1989). Optical Fiber Sensor, Artech House."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1006\/ofte.2000.0355","article-title":"Plastic optical fibers: An introduction to their technological processes and applications","volume":"7","year":"2001","journal-title":"Opt. Fiber Technol"},{"key":"ref_12","unstructured":"Harmer, A.L. (1983, January April). In optical fiber refractometer using attenuation of cladding modes. London, UK."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2261","DOI":"10.1088\/0957-0233\/18\/7\/061","article-title":"A quasi-distributed level sensor based on a bent side-polished plastic optical fiber cable","volume":"18","author":"Lomer","year":"2007","journal-title":"Meas. Sci. Technol"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3100","DOI":"10.3390\/s7123100","article-title":"Fiber optic sensors for detection of toxic and biological threats","volume":"7","author":"Bansal","year":"2007","journal-title":"Sensors"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"6446","DOI":"10.3390\/s90806446","article-title":"A self-referencing intensity based polymer optical fiber sensor for liquid detection","volume":"9","author":"Montero","year":"2009","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1016\/0378-7753(89)80035-7","article-title":"A new method of establishing the state of charge of lead-acid batteries with electrolyte circulation","volume":"27","author":"Armenta","year":"1989","journal-title":"J. Power Sources"},{"key":"ref_17","unstructured":"Snyder, A., and Love, J. (1983). Optical Waveguide Theory, Chapman and Hall. [2nd ed.]."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1364\/JOSA.66.000311","article-title":"Field deformation and loss caused by curvature of optical fibers","volume":"66","author":"Marcuse","year":"1976","journal-title":"J. Opt. Soc. Am"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1049\/el:19780023","article-title":"Power attenuation in bent multimode step-index slab and fiber waveguides","volume":"14","author":"Love","year":"1978","journal-title":"Electron. Lett"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1364\/JOSA.66.000216","article-title":"Curvature loss formula for optical fibers","volume":"66","author":"Marcuse","year":"1975","journal-title":"J. Opt. Soc. Am"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2506","DOI":"10.1364\/AO.11.002506","article-title":"Bending loss in multimode fibers with graded and ungraded core index","volume":"11","author":"Gloge","year":"1972","journal-title":"Appl. Opt"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3180","DOI":"10.1364\/AO.27.003180","article-title":"Exact paths in bent waveguides","volume":"27","author":"Ghatak","year":"1988","journal-title":"Appl. Opt"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1109\/TMTT.1975.1128514","article-title":"Reflection at a curved dielectric interface\u2014Electromagnetic tunneling","volume":"23","author":"Snyder","year":"1975","journal-title":"IEEE Trans. Microwave Theory Tech"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"997","DOI":"10.1364\/AO.42.000997","article-title":"Dependence of bending losses on cladding thickness in plastic optical fibers","volume":"42","author":"Durana","year":"2003","journal-title":"Appl. Opt"},{"key":"ref_25","unstructured":"Club Des Fibers Optiques Plastiques (1997). Plastic Optical Fibers. Practical Applications, John Wiley & Sons."},{"key":"ref_26","unstructured":"Cao, A., Marcos, J., Doval, J., and Pe\u00f1alver, C. (2005, January September). An optimized fiber optic sensor for the measurement of the electrolyte density in lead-acid batteries. Barcelona, Spain."},{"key":"ref_27","unstructured":"Cao, A., Marcos, J., Doval, J., and del Rio, A. (2006, January September). Temperature dependence compensation of the optoelectronics components by means of hardware and data processed. Seoul, Korea."},{"key":"ref_28","unstructured":"Marcos, J., \u00c1lvarez, J., Doval, J., Cao, A., Pe\u00f1alver, C., Nogueiras, A., and Lago, A. (2005, January June). Management electronics system for fast charging lead-acid batteries. Honolulu, HI, USA."},{"key":"ref_29","unstructured":"Marcos, J., Dios, J., Cao, A., Doval, J., Pe\u00f1alver, C., Nogueiras, A., Lago, A., and Poza, F. (2006, January March). Fast lead-acid battery charge strategy. Dallas, TX, USA."},{"key":"ref_30","unstructured":"Marcos, J., and Cao, A. (2006, January September). 7000 hours accelerated testing for plastic optical fibers in lead-acid batteries applications. Seoul, Korea."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Volotinen, T., Griffioen, W., Gadonna, M., and Limberger, H. (1999). Reliability of Optical Fibers and Componentes, Springer-Verlag.","DOI":"10.1007\/978-1-4471-0545-9"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/10\/4\/2587\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T22:01:54Z","timestamp":1760220114000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/10\/4\/2587"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,3,25]]},"references-count":31,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2010,4]]}},"alternative-id":["s100402587"],"URL":"https:\/\/doi.org\/10.3390\/s100402587","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2010,3,25]]}}}