Battery thermal management system

Most VRLA batteries used in telecommunications applications are designed to operate in an indoor environment of 25° C. When placed in an outdoor environment, the batteries must be heated to prevent loss of capacity and must be ventilated to avoid build-up of hydrogen gas that occurs during charging that isn´t properly controlled. The most difficult problem is maintaining the 25° C ambient temperature of the battery in an outdoor environment that can easily exceed 46° C. AH current commercial solutions (thermoelectric, air conditioners, thermosyphons, PCM) require at least additional valuable site space to house the batteries as well as the expense and reliability issues associated with remote cabling, alarming and monitoring. We focused on the fact that the battery represents a large thermal mass and typically has different conductivities in all three directions due to the nature of their construction to develop a split cooling system that can keep the batteries at 25° C +/-2° C via direct contact cooling. This avoids the inefficiency of air mover based systems that monitor and control the unit based off the airflow of the cooler itself. The issue of heating in cold ambient conditions, as well as, hydrogen outgassing is also addressed. The system can be used stand-alone or integrated into existing enclosures. Field performance data will be presented and discussed.