Uninterruptible Power Supply

Factors Affecting Battery Life

All UPS batteries have a limited service life, regardless of how or where the UPS is deployed. While determining battery life can be tricky, there are four primary factors that affect a battery’s overall lifespan.

1. Ambient temperature, Because the rated capacity of a battery is based on an ambient temperature of 25°C, any variation from this can affect performance and reduce battery life. For every 8.3°C average annual temperature above 25°C, the life of the battery is reduced by 50 per cent. 

2. Battery chemistry UPS batteries are electro-chemical devices whose ability to store and deliver power slowly decreases over time. Even if all guidelines for storage, maintenance and usage are followed, batteries will still require replacement after a certain period of time. 

3. Cycling After a UPS operates on battery power during a power failure, the battery is recharged for future use, which is called the discharge cycle. At installation, the battery is at 100 per cent of its rated capacity, but each discharge and subsequent recharge slightly reduces the relative capacity of the battery. Once the chemistry is depleted, the cells fail and the battery must be replaced.

 4. Maintenance For larger UPS models, service and maintenance of batteries are critical to the reliability of the UPS. Periodic preventive maintenance not only extends battery string life by preventing loose connections and removing corrosion, but can help identify ailing batteries before they fail. Even though sealed batteries are sometimes referred to as maintenance free, they still require scheduled service - maintenance free refers only to the fact that they do not require replacement of fluid. 

5. Battery service life Most UPS batteries on the market today are constantly “trickle-charged”- a process that degrades the battery’s internal chemical composition and reduces potential battery service life by as much as 50 per cent. In contrast, Eaton's ABM technology uses sophisticated sensing circuitry and an innovative three-stage charging technique that extends the useful service life of UPS batteries while optimising the battery recharge time. ABM technology also provides up to 60 days’ notice of the end of useful battery service life to allow you ample time to hot swap batteries without ever having to shut down connected equipment. 

This article has been extracted from The UPS Handbook by Eaton

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