Valve-regulated lead/acid (VRLA) batteries are widely used as back-up power sources for telecommunications and UPS. These applications require high-reliability under severe environmental conditions. To meet this demand, the authors company have developed small capacity (12 V, 15-65 A h at C-20/20 rate), long-life VRLA batteries which can endure high ambient temperature. These batteries make use of a new alloy and grid design which has improved resistance to corrosion at the positive plate, while at the same time reduce float current at high temperature. As a result, these batteries have a life expectancy of 13 years at 25 degrees C, and inhibited thermal runaway even under ambient temperatures up to 75 degrees C. The batteries can be installed in outdoor and underground environments.