By Andrew Skelton, Operations Director, CENTIEL UK

When the mains fail, the only thing protecting the critical load is your UPS and your batteries. This is really the only time you will find out if your batteries are up to the job. The consequences of battery failure in this scenario is far reaching, therefore, it is essential that VRLA batteries are properly commissioned and maintained correctly.

Normally, VRLA batteries have a design life of either 3-5 years or 10-12-years. However, this can be a lot less even if they are not maintained properly; or kept at the optimum temperature or charged and discharged incorrectly.

Regular maintenance and service visits for a UPS, includes a visual check of the batteries and this inspection is essential. Maintenance staff are looking out for any signs of corrosion, swelling of the blocks and any indication of leaking or other damage. However, they can’t see inside a battery with a visual inspection.

Impedance testing once per year is important. However, impedance testing doesn’t show how long batteries will last. Even if an impedance test was satisfactory, the application of a real load can result in batteries collapsing quickly if there are issues. For this reason, best practice is to have two maintenance visits per year and carry out an impedance test to assess the overall health of the batteries during the first visit and a full discharge test during the second visit.

Some may be concerned that by discharging batteries may reduce their cycling ability. However, VRLA batteries are designed for approximately 500 cycles, so an annual discharge under test conditions will have little to no effect on the performance of the batteries.

Carrying out both an impedance and discharge test on batteries each year provides detailed information so organisations can ‘know their batteries’. Deterioration can be monitored over time, you would expect to see a small deterioration each year over the life of your batteries. This information helps organisations make informed decisions about the timing of replacements. Having a clear picture of battery health in this way can ensure action taken to optimise functionality and minimise risk of failure.

Your UPS is only as good as your batteries: get them checked on a regular basis. Your power depends on it!

Originally featured in Electrical Trade Magazine Issue 30

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