YouTuber Mikey Sklar takes a four or five year-old dead sealed lead acid battery (small one), removes the seal plate, uncaps the six cells and fills with each cell with “rain water.” After giving the battery a small charge using a “pimp” charger, Mikey demonstrates how you can use a handheld voltage meter to check how each cell is contributing to the total charge. By checking each cell, you can determine if any of the cells are not working and whether that battery as a whole can be restored.
He also mentions a vital point: If he tried to charge the battery while it was dry, he would have likely blown the connection between one or more the cells and those separated cells would no longer be able to contribute to the battery’s total voltage. So…
Don’t charge a lead acid battery before making sure it’s not dried out!
