When it comes to uninterruptible power system (UPS) batteries, knowledge truly is power. By being aware of the factors that influence your batteries’ ongoing performance, you have the ability to extend their life, prevent costly downtime, and ultimately save time and money. Of the four primary factors that affect battery life — ambient temperature, chemistry, cycling and service — we will focus here on the importance of taking every precaution to beat the heat.
While the average life expectancy of valve-regulated lead-acid (VRLA) batteries is generally three to five years, this lifespan is significantly impacted by the factors above. All UPS batteries have a rated capacity that is based on specified conditions, and any variation from this operating temperature can alter the battery’s performance and shorten its expected life.
Furthermore, failure to maintain batteries at their ambient temperature can even void your UPS warranty. Most manufacturers require appropriate documentation to verify temperature for any claim, and usually specify that failure to maintain the recommended temperature range will invalidate the warranty.
The optimum temperature for (VRLA type) UPS batteries is 77°F (25°C), and ensuring that yours remain at this level will maximize the unit’s life and functionality. While a UPS can continue to operate beyond this temperature, doing so will very likely result in diminished performance and lifespan. And we aren’t talking about minimal consequences — in fact, for every 15°F (8.3°C) above the ambient temperature, the life of the battery is reduced by a full 50 percent.
Many users fail to properly maintain control over the temperature in the room dedicated to power protection, thus shortening the life of their UPS batteries and ultimately placing their critical load at risk. When batteries are not properly cared for and exposed to higher temperatures, you can expect your costs to rise and your reliability to plummet.
Batteries actively working inside your UPS aren’t the only ones susceptible to heat. It is important to store any additional batteries in cool, dry and well-ventilated areas where they will not be damaged. They should of course be kept under a roof to protect against any adverse weather conditions, as well as separated from incompatible materials. Finally, be sure to keep batteries away from any fire, sparks or heat.
And while it is paramount to safeguard batteries against rising temperatures, the opposite spectrum can leave you out in the cold. If batteries are exposed to temperatures below 32°F (0°C), they are susceptible to another set of problems. Due to the electro/chemical design of most VRLA batteries, very low temperatures can limit batteries’ ability to deliver sufficient current to power the UPS. As a result, when operated at 32°F, battery runtime can be reduced to less than 50 percent of its normal value.
In our next installment of this series on UPS batteries, we will investigate the return on investment (ROI) of replacing batteries every 5 years.