Standby Battery Conditions

No matter what the composition (VLAR, Li Ion etc), batteries are the cornerstone of any Uninterruptible Power Supply (UPS) and so it is therefore important to understand what can cause batteries to fail so that one can take the necessary preventative measures to maximise their reliability and efficiency.

Common conditions which affect the lifespan and performance of your standby batteries are as follows:

  • Poor environmental conditions both of unused batteries kept in storage, as it is easy to forget that even idle batteries discharge small amounts of energy, and Installed batteries in an un-optimal environment.
  • If batteries are not charged regularly – at least once a quarter when in storage, the life of unused batteries can be significantly reduced and can ultimately lead to total battery failure.
  • The temperature at which batteries are stored is also critical to their performance and lifespan. It is recommended that idle batteries are stored at a temperature of 10°C or less. Typically the rated capacity of each battery is based on an ambient temperature of 20 – 25°C when installed. The accepted rule of thumb is that for every 8.3°C above the recommended ambient temperature, the expected life of a battery can be reduced by as much as 50%
  • The life of a UPS battery can also be stunted due to over cycling (excessive use such as load shedding). When there is a mains failure and batteries are called into action, they need to be recharged so are ready for future use. Constant or multiple mains failures can lead to early life failure. Each cycle and the duration of it affects the rated capacity of the UPS battery. Ultimately there are only so many cycles that a UPS battery can go through before it must be replaced.
  • Ensuring the correct float voltage of a UPS battery is also critical to avoid failure. Undercharging (a low float voltage) can result in sulphate crystals forming, which harden and reduce the overall capacity of the battery. Conversely, overcharging (a high float voltage) can result in internal dryout – thermal runway from a build-up of hydrogen and oxygen gases. This not only results in battery failure but can also cause battery explosion and/or fire.

The key to ensuring that your UPS batteries are operating efficiently is to have regular servicing to prevent any irregularities which could result in catastrophic failure and consequences.

For more information email sales@jups.co.za or call the office Toll Free on 0800 JUP UPS.

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