Battery Testing‎

Why battery testing?

battery racking resized

 Battery Lifetime

No battery within a UPS will last forever and it is common practice to replace battery stocks every 3-5 years when they come to the end of their natural life.

When is end of life ?

Due to their very nature, every battery within a string will behave slightly differently. Each will be affected by a great deal of factors not least the temperature at which they are stored, how often they are called upon to work and the level to which they are discharged when needed.

It is possible then that a single battery may well fail well within its 3-5 year expected lifetime whilst all others around it are still in perfectly good condition. This then puts additional strain on adjacent batteries in the string which then begin to fail in a ‘domino-style’ effect.

However whilst the majority of UPS available today will have the capacity to monitor the overall battery string voltage they do not monitor individual cells themselves so any failure is not immediately apparent.

If a single battery failure occurs within a string, often the entire string of batteries (anything from 32 to 48 individual units per string) ends up being replaced at high cost. This is mainly due to the difficulty in immediately being able to identify one single point of failure. The result is that often the importance of getting the UPS back up and running again as soon as possible, often overcomes the issue of cost!

Early warning.

Battery testing (or more correctly a battery ‘impedance test’) carried out annually from the time they are installed from new, will provide an annual ‘health check’ and health ‘history’ over their lifetime. This is the case for every individual battery in the string as opposed to just the overall string itself. Should any individual battery show early signs of failure or weakness then this can be replaced as an individual unit avoiding the ‘usual’ practice and cost of replacing whole strings.

Whilst this will never ‘negate’ the eventual requirement for a full battery change it will help monitor and maintain the integrity of the string. This maximises its lifetime and avoids the high costs of ‘panic’ changing entire strings should a weakness be identified or worse still failure occur when under load.

 The potential Savings

Savings Example: The table below gives an example (based on a 30kVA UPS with a 30 min. runtime) of the potential savings which can be made due to an impedance test identifying only one faulty battery within a string vs changing the whole string which may be unnecessary. To allow us to provide you with a more detailed outline of our battery impedance testing offers and pricing please contact us.


The test

Replacing a whole battery string is a costly exercise. A preventative annual battery impedance check will test each individual block within the string. This can identify any weak or failing individual unit, leading to a much lower replacement cost (or possibly the battery being re-conditioned) compared to the expense of swapping out an entire string. At the same time this will of course check the overall battery string health ensuring that any UPS will deliver the protection expected from it when needed.

Each battery test generates a complete unit by unit report giving impedance readings and condition reports for each cell together with any service / replacement recommendations.

The duration of the battery test is obviously dependent on the size of the unit but will take between 2-3 hours and requires a fully qualified engineer due to the high voltages involved within a UPS unit.

For more details on impedance testing and the latest price offers from UPS Systems please contact us.