(1) The opening pressure of the relief valve is too high, or the relief valve is blocked. When the pressure inside the body increases to a certain level, the valve cannot be opened normally, in which case the bulge is bound to be deformed.
(2) When the floating charging pressure is set too high and the charging current is high, the O2 precipitation on the positive electrode plate is accelerated without the time for recombination in the negative electrode. At the same time, the temperature in the battery rises rapidly. When the exhaust is not enough and the pressure reaches a certain level, the VRLA battery appears bulging deformation.
(3) In VRLA battery charging operation, especially in series battery pack, if the battery pack has been charged, the battery with poor quality will often have poor internal gas compounding and other phenomena, resulting in bulging.
(4) As VRLA battery is of a liquid-poor design, there is a reserved escape way for gas combination, and if there is a "liquid-rich" phenomenon, it will prevent the generated O2 from diffusing to the negative pole, reduce the compound rate of O2, and increase the internal pressure.
