Maximising battery efficiency in a UPS

Power Control
17 Jan 2019

Whether a VRLA or Lithium Ion composition, batteries are the fundamental components of an Uninterruptible Power Supply (UPS) and so their failure could result in catastrophic consequences. It is therefore important to understand what can cause batteries to fail in order to take the necessary preventative measures to maximise their efficiency.

One of the most common reasons of battery failure is poor storage. Especially of unused batteries as it is easy to forget that even idle batteries discharge small amounts of energy. If batteries are not charged regularly – once a quarter, 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 50°F (10°C) or less. Typically the rated capacity of each battery is based on an ambient temperature of 68 – 77°F (20 – 25°C). The accepted rule of thumb is that for every 47°F (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. 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 effects 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 fire.

The key to ensuring the UPS batteries are operating efficiently is to have regular servicing to prevent any irregularities resulting in a UPS failure.

Our battery services page provides more information on the importance of battery maintenance and how Power Control carry out their servicing.

For more information download the Advanced Battery Testing whitepaper or visit our Battery Servicing Page. Alternatively, email or call the office on 01246 431431