Investigation on Operating Characteristics of Individual Cells in a Lead-Acid Battery Pack

Abstract

Similar to series-connected batteries, series-connected cells in a battery pack also suffer from the perplexity of unbalanced voltage while charging or discharging processes, especially for lead-acid batteries. This paper is to study the impact on capacity reduction under different operation conditions, such as different float-charging voltages, different cut-off discharging voltages and even discharging to negative voltages. The results reveal that the health of battery cells is more significantly affected by float-charging voltage than by the discharging cut-off voltage. However, discharging a cell into exceedingly negative voltage incurs a destructive consequence. A bypass protection circuit is proposed to mitigate the deterioration rate of battery cells. Experimental results show that the capacity reduction rate can be decreased distinctly.

Enhanced coulomb counting method for estimating state-of-charge and state-of-health of lithium-ion batteries

“…To exclude error caused by the imbalance problems of the series-connected batteries, singlecell lithium-ion batteries are used for the experiments [13]. It is noted that the operating voltages and currents are measured by programmable DC power supply and electronic load.…”

Investigation on intermittent discharging for lead‐acid batteries

“…The charging current and voltage were designated to obtain a maximum releasable capacity but not to cause premature aging (Hsieh et al, 2007). The effective battery capacity is calculated by the coulomb counting method from the full-charged state to the exhausted state, at which the loaded voltage declines to the cut-off voltage of 1.7 V. Figure 3(a) shows that the entire working period with the intermittent current is more than twice that with constant current, indicating that intermittent discharge has the advantage of more releasable charge.…”