When it comes to uninterruptible power systems (UPSs), knowledge is truly power.

And the more you understand about batteries —the heart of every UPS solution— the more likely you will be to avoid devastating downtime. As the most vulnerable part of any UPS, batteries are the leading cause of UPS failure and load loss. Knowing how to properly maintain and manage them is key to extending their service life.

Bolster your battery knowledge with these 10 UPS battery facts:

1. All batteries will die — Regardless of the brand, every UPS battery will reach the “end of useful life,” which IEEE defines as the point when it can no longer supply 80 percent of its rated capacity in ampere-hours. From this juncture on, the battery’s aging process will be accelerated so be sure to replace it.

2. No batteries are truly “maintenance-free” — While valve regulated lead acid (VRLA) batteries demand substantially less care than traditional wet cell batteries, they nonetheless require consistent battery maintenance. In addition to visual inspections and proper cleaning, a variety of measurements should be recorded on a regular basis, including float voltage, charge output current and voltage, temperature and cell values.

3. Don’t trust battery lifespan claims — Although the average life of VRLA batteries is generally considered to be three to five years, it can be significantly less. Actual lifespan varies dramatically due to a number of factors including environmental conditions, the number of discharge cycles and the amount of maintenance received.

4. Batteries die for multiple reasons — Pick your poison; there’s no shortage of negative factors that can cause a battery to fail. High or uneven temperatures; inaccurate float charge voltage; loose inter-cell links or connections; loss of electrolyte due to damage or drying out; lack of maintenance; and aging are among the most common causes of battery failure.

5. Maintaining ambient temperature is essential — Batteries can’t operate in an environment that is too hot or too cold because it compromises their ability to store and dissipate energy. The recognized ambient temperature for UPS batteries is 77°F (25°C) and while a UPS may continue to operate beyond this rating, doing so will very likely result in significantly reduced performance and lifespan. 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.

6. Battery monitoring reduces downtime risks — As the most vulnerable part of a UPS system, batteries greatly benefit from a predictive monitoring system. Evaluating many variables and producing ongoing analytics, monitoring solutions can pick up on subtle changes that signal impending battery failure, thereby providing advanced warning before your system fails.

7. Don’t neglect stored batteries—UPS batteries that sit unused will experience a decreased lifespan. When it storage, it is recommended that they be charged every three to four months to avoid permanent loss of capacity, which will occur between 18 and 30 months. To prolong shelf life without charging, store batteries at 10°C (50°F) or less.

8. Don’t overlook the UPS battery service — Your preventive maintenance plan should cover not only the UPS components, but the batteries, as well. Regularly scheduled service allows trained technicians to inspect, test, calibrate and upgrade battery components, ensuring factory-specified performance and longevity. Be sure your contract includes both the UPS and its batteries.

9. Hot-swappable and user-replaceable batteries are not the same thing —Batteries that are hot-swappable are capable of being changed out while the UPS is running. On the other hand, user-replaceable batteries — generally found in smaller UPSs — indicate that they don’t need any special tools or training in order to be replace. Batteries can be both hot-swappable and user-replaceable.

10. Size up the discharge rating — Most batteries are rated for more than 100 discharges and recharges. However, it isn’t unusual to see a marked decline in charging capacity after as few as 10 discharges. The lower the charge that the battery can accept, the less runtime it is able to deliver, so look for batteries with a high-rate design capable of sustaining stable performance for a long service term.


Upping your UPS battery knowledge can extend its lifespan, save time and money, and prevent costly downtime. Intelligent Power Solutions has the expertise and resources to help you ensure optimal performance from your UPS batteries — and your overall power protection solution. Call us today for a quote, consultation or to answer any additional questions you may have.

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