The prediction of the state-of-charge of some commercial primary cells

Peer Reviewed: Electrochemical Impedance Spectroscopy for Better Electrochemical Measurements

“…First, the Nyquist and Bode plots are almost always ideal, as predicted, because they represent the snapshots of impedance during a short period of the experiment. This situation is rather unusual because the impedance signals acquired by other techniques are hardly ideal (32,(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51), perhaps because the impedance obtained by the FRA is the time-averaged signal over the period of the measurement. Even for a complex system, such as aniline oxidation leading to the formation of polyaniline, nearly ideal semicircles are observed (52).…”

Second‐Order Harmonic in the Current Response to Sinusoidal Perturbation Voltage for Lead‐Acid Battery: An Application to a State‐of‐Charge Indicator

“…When a sinusoidal alternating voltage V(o~,t) = V0 sin ~0t [1] is superimposed on an inherent terminal voltage, Vt, of a battery as input, the current response is represented as a Fourier series expansion I(oJ, t) = I0 + ~ I,, sin (n~t + 6) [2] where co = 2~rfl.f: frequency) and 6 are the angular velocity of the imposed sinusoidal voltage and phase deviation of the response, respectively. The direct current I0 corresponds to faradaic rectification effect, and I with the subscripts n = 1, 2, 3,..., are amplitudes of the fundamental tone, second-order harmonic, third-order harmonic, .…”

“…Most indicators proposed so far are based in principle on terminal voltage (1), impedance (2), and especially the concentration of sulfuric acid in the case of lead-acid batteries. Density (3), refractive index (4), and saturated humidity (5) have been studied as physical properties representing the concentration of sulfuric acid.…”

“…The state-ofcharge can also be obtained from integrated current. To measure these physical quantities accurately, simply, and automatically in packed batteries, many devices have been proposed (1)(2)(3)(4)(5). Still, many problems remain, and only a few devices have proved good enough to be of practical use.…”

“…Finally, fundamental wave impedance is largely dependent on rest time for lead-acid batteries (6). An attempt is now being made to apply it to primary cells before use (2).…”