Research On The Fast Charge Of VRLA Batteries At High Current

Nowadays,lead-acid batteries still have the largest market-share in the world which is closely connected with our lives.But they subject to the shortcomings,such as poor battery life,slowly charging and the low popularizing rate of charging equipment.The batteries can not meet the demands of people in their daily lives.So it is so hard to replace fossil fuels with lead-acid battery.In order to improve the charging rate and guarantee the working performance of lead-acid batteries,it is necessary to investigate a new suitable charging method and study its influence on lead-acid batteries.The object of the research is 12 V 12 Ah batteries.A new rapid charging method at high current is successfully investigated and test its feasibility in the low temperature environment.At the same time,in order to find out the failure cause of lead-acid batteries which charged by the new method,we compared it with conventional charging method.The following conclusions have been drawn:1.The new fast charging method at high current:The first step is constant-current charge at 36A for 10 minutes and the upper limit of voltage is 14.75 V.The second step is constant-current discharge for 10 seconds.The third step is constant-current charge and the upper limit of voltage is 14.75 V.The fourth step is constant-voltage at 14.75 V and the lower limit of current is 0.35 A.We can make the battery up to 80%state of charge amount within 20 minutes through the new fast charging method.2.In order to apply the new fast charging method at low temperature,all upper limit of voltage are changed to 15.75 V and the value of constant-voltage is 15.75 V.In addition,a step is added which is constant-current charge for 10 seconds to preheat the battery before the first constant-current charging step.But the number of cycles is only 60.So it is inappropriate to apply the new fast charging method at low temperature.3.The failure cause of lead-acid batteries at room temperature through the new fast charging method is the active mass soften of positive plates.The failure cause of lead-acid batteries in room temperature through the conventional charging method is the active mass soften and the fillet of grid broken of positive plates.The failure cause of lead-acid batteries at low temperature through the fast charging method is dry of electrolyte.4.Compared with water loss under the different charging conditions,the result show that internal resistance is negative correlation with temperature.The Water loss is negative correlation with temperature.Compared the failure batteries under three different charging conditions.The results show that temperature is the main factor which can affect the content of ?-PbO2,?-PbO2,PbSO4 and particle size of ?-PbO2.The effect of high current on them is not significant.The specific area of active mass charging at high current is smaller than charging in conventional method.The specific area of active mass charging at low temperature is smaller than charging at room temperature.The tests show that the value of current is negative correlation with specific area of active mass and the temperature is positively correlated with specific area of active mass.The grid corrosion of the upper part is more serious than the middle part of the positive plate of lead-acid battery.The grid corrosions are approximate when charging at high and low current.The high current can not aggravate the degree of grid corrosion of positive plate of batteries.