Automotive Type Batteries in Long Term Float and UPS Applications

B. C. Hydro has been using lead calcium maintenance-free automotive batteries for over ten years in small 24 VDC communications grade power systems as well as 72 and 120 VDC UPS applications. Over 300 batteries are now in use and experience has been very favourable. Cost savings have been large and as well there have been some safety benefits. Only four failures have been reported: two were traced to cracked separators, one to a poor internal connection, and one to grid corrosion. This paper describes the selection of lead calcium maintenance-free batteries, their charge-discharge curves, the design criteria for various systems, and some maintenance considerations.