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Common UPS Battery System Failures

  |   UPS Batteries   |   No comment

Most UPS catastrophes occur because of battery error. While some large-scale uninterrupted power supply systems‘ batteries are vulnerable to failure, knowing what can cause these failures and what can be done to prevent them is one way to avoid being the victim.

A UPS battery is essentially an electromechanical device that stores and delivers power to the equipment or data centres; but this ability tends to slowly depreciate over time. Regardless of how well-maintained the batteries are, they will still have to be replaced once they reach the end of their lifespan.

Things to focus on

On average the service life of standard VRLA (Valve Regulated Lead Acid) batteries is 3-5 years. However, there are many chemical, environmental as well as user-related aspects that significantly impact the battery’s lifespan. Some of the common UPS battery system failures and mistakes to avoid which can help increase the lifespan of your UPS battery are discussed here:

Improper storage

Even if you have batteries that aren’t being used, their lifetime starts to decrease. This is because a lead-acid battery will automatically discharge small amounts of energy over time. The one way to prolong the storage life of batteries is to charge it every 3-4 months of storage. If you don’t do this, there will be permanent loss of capacity within a matter of 6 months. It’s best to store unused batteries at temperatures 10°C/less.

Higher ambient temperatures

Every battery has a specific rated capacity which is based on an ambient temperature of 25°C. A rise in this temperature can impact the lifespan as well as the performance of the battery. Routine maintenance checks can go a long way in detecting thermal hotspots and in verifying proper ventilation.

Excessive cycling

Once a UPS systems operates on its battery power when there is a power failure, the battery then recharges for later use (this event is referred to as a discharge cycle). Once the battery is installed, its functions at 100% of its rating capacity. But every subsequent discharge and recharge reduces the battery’s capacity a little.

Incorrect float voltage

Every UPS battery manufacturer specifies the charging voltage range required for their specific cell designs. If the batteries are constantly charged outside of these particular parameters, it can cause considerable damage.

Undercharging/low voltages can also result in sulphate crystals formation on the battery’s plates. The crystals eventually harden and also reduce the battery’s available capacity over a period of time. If the battery is over-charged with a float voltage that’s too high, it can cause a build-up of excessive oxygen & hydrogen gases which in turn can result in an internal dryout and thermal runway. These conditions can result in an explosion or fire breakout.

Improper battery applications

A UPS battery is specifically built for use in a UPS in the manner that other batteries are built specifically for certain appliances. The former are built to deliver very high rates of energy over shorter timespans. If UPS batteries are used for switchgear or telecom applications, they will have to operate for a much longer than what they are designed form which can result in overheating and failure.

The commonest failure modes of VRLA batteries occur in the open circuit and these are generally caused by a cell dryout. A UPS system generally has a SERIES-connected battery system that provides a high current to the UPS System’s DC Bus. Even if a single cell in this string opens, it will end up breaking the current in the whole string; this means, even that one failed battery cell can affect your entire infrastructure.

If you want to know more about our power products and services, don’t hesitate to contact us at KaRaTec Power Supply Pty. You can give us a call at 612 9808 1127. You can also fill in this contact us form.

Thanks for reading,
Karatec Power Supply Pty
612 9808 1127

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