It can be treated by low current charging method as follows: 1. First, pure distilled water was added to the electrolyte to reduce the specific gravity to below 1.2, and the page reached the standard line. 2. Start charging at a current of half the discharge rate of 10h, and stop charging at a bubble voltage of about 2.4V for 30 minutes. Reduce the charging current to 1u002F4, with the discharge rate of 10h, and stop charging for 20min until severe bubbles appear on the positive and negative plates. 4. Continue charging to normal according to the half current of 10h discharge rate. 5. Note: During charging, acid and electrolyte shall not be added to the battery at will, and the ratio shall not exceed the specified value.