The life of a battery bloc can vary dramatically especially when used in a UPS System , the manufacturer will always state the expected life of a battery bloc on the proviso that it has a pure dc float voltage applied to it and that the ambient temperature is restricted to 20 ? C. If these parameters are adhered to, one can expect to achieve the 5 years life from a 3 ? 5 year design life battery or the 10 years of a 7 ? 10 year design life battery bloc, omitting manufacturing failures.

Unfortunately we do not live in a perfect world and as a result there are limitations applied to the battery bloc, one is the ambient temperature, although a number of rack-mounted UPS systems may luxuriate in ambient temperatures of 20 ? C or less because of the demands of the IT equipment, due to the nature of the design of the UPS there is generally insufficient space to achieve a significant airflow round the battery blocs and as a result they will fail the UPS system battery test after a mere 2 ? 3 years.

In this situation the requirements of Uninterruptible power supplies and their installation mean that UPS maintenance is unlikely to detect the failure of the battery pack, often due to the fact that after a very short period of time the UPS system is hidden in a mass of communication cables. The most positive approach under these circumstances is to rigorously implement a two-year replacement battery programme to ensure the integrity of the backup UPS system. This also applies to Generators. Yes, even diesel generators require batteries to supply the current to start.

Flat or failed batteries render the generator useless. Call outs to such problems are chargeable and yet can be avoided by a regular maintenance regime.

In larger UPS systems the problems arising are often due to location; no-one wants the local radiated noise of Uninterruptible power supplies to impinge on their working environment and, as a result the uninterruptible power supply will be located in a basement perhaps, where the ambient temperature is not ideal for batteries and maybe the saying,? Out of sight is Out of mind,? is true. In the case of battery life, ignorance is not bliss. Batteries will fail the question is whether you are prepared or just waiting for it to happen,

As a result of the location the ambient temperature can often exceed 25 - 30 ? C and this potentially could decrease the expected life of the battery. For, prolonged use at 30 ? of VRLA (valve regulated lead acid) batteries the expected life can decrease by 50%, if the ambient temperature is raised to 40 ? C the life of the battery will fall by another 50%. Therefore at an ambient temperature of 40 ? C the expected operating life of a 7 ? 10 year life battery has fallen to 1.75 ? 2.5 years!

In this case even UPS maintenance will not save the battery, all it can do is to report on the rapid deterioration of the battery bloc.

Fortunately these extremes covered by these scenarios are not too common but they highlight the need to record the operating conditions by regular UPS maintenance and to ensure that there is an emergency 24/7 callout cover in place in the event of the unexpected happening. Be prepared!