Large stationary lead storage batteries play an ever increasing role in substation and generating station control and power systems and in providing the back-up energy for emergencies. This recommended practice fulfillls the need within the industry to provide common or standard practices of maintenance, testing, and replacement. The methods described are applicable to all installations and battery sizes. The installations considered herein are designed for full-float operation with a battery charger serving to maintain the battery in a charged condition as well as to supply the normal dc load.