A battery charger is a device that charges batteries for consumer or non-consumer devices. Battery chargers may be stand-alone equipment, or embedded in other products. Examples of consumer devices which use battery chargers include cordless and cellular phones, cordless power tools, laptop computers, and golf carts. Non-consumer devices which use battery chargers include two-way radios, emergency backup lighting, and lift trucks.
The California Energy Commission (CEC) completed state-level energy efficiency standards for both consumer and non-consumer battery chargers in January 2012 which took effect in 2013 for consumer chargers and 2014 for industrial chargers. In 2013, Oregon adopted similar standards for battery chargers which went into effect January 1, 2014.
DOE issued a proposed rule for the first-ever federal energy efficiency standards for consumer battery chargers in March 2012. However, stakeholders raised questions about the availability of more efficient products and expressed concern that proposed federal standard would pre-empt the more stringent California state standards. In March of 2013, DOE asked for more information, focusing on products certified as compliant with the California standards. After reviewing the data, DOE issued a new proposed rule, and in May 2016 a final rule, for consumer battery chargers with standard levels similar to those in California and Oregon.
Between 2012 and 2016 battery charger manufacturers shifted their product lines to comply with the California and Oregon state standards so that about 95% of consumer battery chargers sold nationally already meet the new federal standards.
DOE estimates that the 2016 national standards for consumer battery chargers will lower national energy usage by 0.17 quadrillion BTUs, save between $0.6 and $1.2 billion, and reduce CO2 emissions by 10.8 million metric tons over 30 years of sales. These savings are measured from the 2016 national baseline, which had been significantly raised by the earlier California and Oregon standards, as mentioned above. The combined savings the state and federal energy efficiency standards for battery chargers is significantly higher.
DOE’s final rule will take effect in 2018. California and Oregon standards for consumer chargers will be preempted once national standards go into effect, but state standards for non-consumer chargers will remain in effect.
Battery chargers operate in three modes: no-battery, maintenance, and active modes. In no-battery mode, the charger is plugged into the wall but is not connected to a battery. In maintenance mode, the battery is fully charged yet still connected to the charger. In active mode, the battery is in the process of being charged. To ensure energy savings during actual use, it is important that battery chargers be efficient in all three modes of operation since the amount of time spent in each mode varies significantly among products and among users of a given product. Inefficient battery chargers often continue to provide constant current to the battery even after the battery is fully charged. Simple solutions significantly reduce power consumption in maintenance mode.