Measuring Energy Efficiency Improvements in Industrial Battery Chargers

Abstract

Industrial battery chargers have provided the energy requirements for motive power in industrial facilities for decades. Their reliable and durable performance, combined with their low energy consumption relative to other industrial processes, has left the core charger technology unchanged since its introduction to the market. Recent improvements in charger technology have led to a new generation of high frequency chargers on the market that can provide energy efficiency improvements over existing Silicon Controlled Rectifier (SCR) and Ferroresonant charger technologies. We estimate there are approximately 32,000 three phase chargers in use within Pacific Gas & Electric Company’s service area, using roughly 750 to 1,000 GWh per year. A 10 percent efficiency improvement on every charger would save about 75 to 100 GWh per year. There are three areas of energy losses in the battery and charger system: • Power Conversion Efficiency (energy out of charger vs. energy into charger) • Charge Return (energy out of battery vs. energy into battery): some amount of overcharge is necessary for battery health, but chargers vary in the degree which they overcharge • Standby losses when no battery is connected. PG&E and Southern California Edison (SCE) are testing industrial battery chargers according to a California Energy Commission (CEC) approved test procedure. This test procedure, developed with charger manufacturer input as part of the CEC’s Codes and Standards process, specifies test conditions during active charge, maintenance charge and standby modes. The results from this testing are expected to provide independent confirmation of vendor claims of energy efficiency improvements during all modes of charger operation, and will form the foundation of data for utility energy efficiency programs. Initial test results of one battery charger from each technology type show the Hybrid and High Frequency technology as the top performers when compared to the SCR and Ferroresonant chargers. Multiple chargers from each technology group will be tested in the first half of 2009 to determine an average performance for each technology type. The full set of results will be available in summer 2009.