Discharge/Load Testing

The list shown below describes some of the options available for the testing of batteries. This can be used in conjunction and combined with any site routines.

In all circumstances all work undertaken will be in accordance with BS EN 50272:2-2001. All tools should be fully maintained, operational, insulated and calibrated, where necessary.

  1. Capacity Testing - British Standard style.

    For Lead Acid, this is normally carried out in accordance with the details of BS6290 and the relevant parts dependant upon cell design and type. Essentially the battery is discharged at a Constant Current via the use of a resistive Load Frame. This is done in accordance with the manufacturer’s data for a period of approximately 3 hours (temperature dependant and variable). The battery and cells are discharged to a predetermined end voltage and the time is logged. Each individual cell voltage is logged at half hour intervals, along with overall battery voltage and temperature.

    For NiCad’s the discharge is usually completed over a 5 hour period.

    This gives the advantage of checking the performance of every individual cell, in accordance with the manufacturer’s data, and an accurate prediction of life and autonomy can be extrapolated.

  2. Load Testing - UPS / System Autonomy requirement

    This is normally carried out in accordance with the details of the sites Autonomy requirements, or ‘standby time’. The battery is discharged either through the UPS / System or via the use of a resistive Load Frame. The load may be variable or constant and is entirely dependant upon the requirements of the system of which it is supporting. Discharge times can range from 1 minute to 1 hour or more. Normally the test time is much shorter than the above method; this then limits the amount of data that can be collated during the test. Where possible battery overall volts, current and temperature are logged for the duration, with the possible addition of monitoring a selection of ‘pilot cells’. The information retrieved can be used to compare with previously obtained data for the determination of loss of performance or decay.

  3. Drop Testing - Engine starting / Switch Tripping

    This is normally carried out in accordance with the details of the equipment being supported. The battery is discharged by performing the task for which it is installed. The load will probably be variable and is entirely dependant upon the requirements of the system of which it is supporting. Discharge times can range from 1 second, or less, to 3 or 4 minutes or more. This then limits the amount of data that can be collated during the test even further, so electronic data logging devices are used. Where possible battery overall volts, current and temperature are logged for the duration, with the possible addition of monitoring a selection of ‘pilot cells’. This data can then be ‘overlaid’ or compared with previous tests for any loss of performance or decay.


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