A Beginners Guide To The “Design Life” Of A Battery

December 18, 2019
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Craig Fischer
Posted in Business
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In most cases, people become confused about the manufacturer’s warranty on batteries and the battery design life. Some batteries present a ‘design life’ of five to ten years, but this can lead to questions if the batteries do not last the indicated design life period and must be replaced earlier than expected. It is important speak to a professional UPS Battery Shop to understand the terms used fully before you purchase as the battery warranty and battery design life are very different factors.

All batteries present a design life meeting the parameters required for Eurobat Classification. This means if the normal operating conditions of a battery are consistently met, then the battery should have the indicated design life period. Service life is greatly related to the battery’s working conditions; however, in everyday operating conditions they are not met constantly.

What Are The Factors Effecting A Battery’s Service Life?

#1: Ambient Temperatures

Environmental factors need to be taken into account as they can severely affect the battery life, particularly the temperature. Field and laboratory research show that the best rule to calculate battery life is the temperature. According to studies, a battery’s design life is reduced by 50 percent when the operating temperature rises by ten degrees Celsius. In theory, this means the battery has an operating life of ten years at 20 degrees Celsius will last only five years if operating at 30 degrees Celsius. If the temperature alters according to the levels, the battery life is based on a time weighted average of the temperature fluctuations. This is often the main cause of failure in VRLA batteries that do not meet the indicated design life irrespective of the manufacturer.

#2: Float Charge Ripple

Excessive ripples on the D.C. battery supply can result in a reduction of battery performance and life. It is therefore advised that a set voltage regulation be imposed across the system, including the battery load without a battery connection. In steady conditions, the load will be better than approximately one percent to five percent or 100 percent. Ripple type excursions, including transient excursions, can be provided when the system shows a peak to peak voltage. Of course, the battery needs to be disconnected while the load remains connected. Regulation limits should fall within approximately 2.5 percent of the average battery float voltage. It is essential that the current is not operational when a battery operates using float conditions. One should, rather, reverse the operation to discharge mode.

#3: Float Stabilisation Ripple

The float stabilisation ripple is a format where the demands of the battery load are not in-sync with the capabilities of the rectifier making the battery responsible for stabilising the system. Certain static UPS systems operate in this manner with the operating condition being compared to shallow cycling. In this situation, the average battery characteristics do not apply, and the manufacturer needs to provide optimal operation conditions.

#4: Deep Discharge

It is advised that, at the discretion of the battery user, low voltage disconnect features should be utilised in the connection equipment. However, it is evident that there are certain circumstances where optimal battery performance will preclude the use of low voltage disconnection. In this situation, it is recommended that the battery is replaced following deep discharging.

#5: Failed Batteries

Not replacing failed batteries at the time of discovery tends to place more stress on the string of batteries. This means that the battery string may receive an undercharge or overcharge from the UPS. In the long term, failed batteries can have a devastating effect on the battery string and reduce their service period.

Final Words On The Matter

In conclusion, considering the various environmental factors and conditions beyond a manufacturer or user’s control, batteries degrade at different speeds with the design life being a mere guide as to how long the item will function. While one can expect the 10-year battery design life to be operational for longer than the five-year option, this is not always the case. In reality, the continuous fluctuation in the environment means the design life and service life of a battery are rarely the same.