24 Hour Emergency Power Services • Call 608-661-9910

Close Menu
UPS Battery Replacement

Five Leading Causes of UPS Battery Failure

Battery failure is the leading culprit behind the majority of UPS catastrophes. But despite batteries’ vulnerability to premature failure, you don’t have to be a victim. We’re going to run through the top five causes of premature battery failure and how you can prevent it.

UPS batteries are electro-chemical devices whose ability to store and deliver power slowly depreciates over time. No matter how well you maintain, store and use your batteries, they will still require replacement when they have reached their end of life.

The general service life of a standard Valve Regulated Lead Acid (VRLA) battery is three to five years. However, there are a number of environmental, chemical and user-related factors that can substantially affect a battery’s life. These are the primary mistakes to avoid to stretch the most life out of your UPS’s battery.

Factors that Cause Premature Battery Failure

Nothing can be done to prevent a battery from eventually reaching its end-of-service life. However, avoiding the following mistakes can help ensure a maximum lifespan.

1. Poor storage of unused batteries – Even as a battery sits unused, its lifetime begins to decrease. That’s because lead-acid batteries automatically discharge small amounts of energy.

To prolong a battery’s storage life, we recommend you charge it every three to four months of storage. If you don’t, you could see a permanent loss of capacity in as little as six months. You can also prolong your unused battery’s storage life by storing it at a temperature of 50°F (10°C) or less.

2. High ambient temperature – The rated capacity of every battery is based on an ambient temperature of 77°F (25°C). Any variation, but especially increased temperature, can affect performance and lifespan. As a general rule, for every 15°F above the recommended ambient temperature, the expected life of the battery is reduced by 50 percent. Routine maintenance checks can help detect thermal hotspots and verify proper ventilation.

3. Over-cycling – After a UPS operates on battery power during a power failure, the battery recharges for future use, an event called the discharge cycle. When a battery is installed, it is at 100 percent of its rated capacity. However, each discharge and subsequent recharge slightly reduces the capacity of the battery.

4. Improper float voltage – Every battery manufacturer will specify the charging voltage ranges for their own cell design. If a battery is consistently charged outside of these parameters, it can cause significant damage.

Undercharging or low voltage can cause sulfate crystals to form on the battery plates. These crystals will eventually harden and reduce the available capacity of the battery over time.

Overcharging with a float voltage that is too high can cause excessive hydrogen and oxygen gases and can lead to internal dryout that, once accelerated, can cause thermal runaway – resulting in failure or even fire and explosion.

5. Incorrect battery application – UPS batteries are made specifically for UPSs, just as other batteries are made specifically for their respective appliances. UPS batteries are built to deliver extremely high rates of energy for a short time, generally up to 15 minutes.

Conversely, other batteries, such as telecom and switchgear batteries, are designed to run for longer periods of time, typically between four and eight hours. If a user runs a telecom application with a UPS battery, it will force the battery to run for much longer than its intended purpose. This could cause the battery’s plates to overheat and fail.

The most common failure mode of a VRLA Battery is an open circuit, most often caused by cell dryout. UPS systems typically have a SERIES connected battery system to provide a high current to the UPS System DC Bus. If one cell in a string opens, it will break the current in the entire string. In short, just one failed battery cell can bring down your entire infrastructure.

Just how much would a more efficient UPS save you? Find out - Download our calculator

How Regular UPS Maintenance Checks Prevent Battery Failures

Preventative maintenance includes visual inspection, battery voltage testing, thermal image scans to test for hot or abnormal conditions, and retesting the torque on the battery terminal connections. If tests show any irregularities, we can determine how critical the situation is and if it makes sense to replace the batteries.

Regular battery service and maintenance is critical in ensuring the reliability of your UPS. Preventative maintenance not only helps connections and removes corrosion, but it can also identify an unhealthy battery before it fails.

You can’t make your UPS battery last forever, but with the proper storage, care and maintenance, you can help increase its longevity, and catch a failing battery before catastrophe strikes.

Is your battery backup ready? Learn more about battery testing, maintenance, and replacement. Contact QPS today.