| Floating current can evaluate the state-of-health of valve-regulated lead/acid (VRLA) batteries in the floating period. When the batteries are fully charged, the lower floating current is, the more healthy VRLA batteries are. However, floating current will increase gradually as VRLA batteries are in float charge condition. At the same time, thermal runaway and water loss are caused. As a result, the service life of battery decrease.Through the comparison of different producing technics in self-discharge experimental, positive grid corrosion experiment, capacity experiment, gas collected experiment, floating current test of VRLA batteries and voltage sweeping measure of work electrode, we study the factors that influence floating current. In the main, the change of producing technics has less influence on self-diacharge, capacity of VRLA batteries and on grid corrosion. relatively, the content of tin at positive grid alloy, electrolyte densities and electrolyte additives are main factors. The results of gas collected experimental, floating current test of VRLA batteries indicate that influence of gas evolution current on floating current is great. Floating current decreases as the gassing volume is less. There are several parameters determine the gas evolution, These parameters are the content of tin at positive grid alloy, electrolyte density, electrolyte additive and ampere density. This conclusion was reinforced by other data for oxygen evoluation potential and hydrogen evoluation potential on work electrode.From these results, it was concluded that floating current is lowest when the content of tin at positive grid alloy is 1.5mass%, electrolyte density is 1.32g/mL, electrolyte additive is colloidal silica and ampere density is 2mA/cm2. At the same time, other factors like positive additive-red lead, increase of curing temperature and H2SO4 density, negative additive have less influence on floating current, some even have negative effects.
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