The soaking step of battery formation, was investigated after the addition of 181 ml of sulfuric acid solution to plates that were allowed to rest for 5, 10, 15 and 30 min and then removed and dried. The same procedure was repeated three more times with new plates and allowed to rest in sulfuric acid solution for minutes. The results indicate plates with a higher content of sulfate display a final monobasic lead sulfate content larger than displayed by plates with smaller amounts of sulfate. Crystal sizes were also followed as a function of time during the soaking period, demonstrating the possibility of extending the use of X-ray diffraction in the observation of crystal sizes of lead compounds in this and any other step of battery production. (C) 2003 Elsevier B.V. All rights reserved.