MAINTENANCE OF BATTERIES FOR EXTENDING ITS LIFE

Quantifying the combined effect of the four factors that affect battery life discussed in the previous page is difficult. You need a way to determine when a battery is near the end of its useful life so you can replace it while it still works, before the critical load is left unprotected. The only sure way to determine battery capacity is to perform a battery run-down test. The module is taken off line, connected to a load bank and operated at rated power until the specified runtime elapses or the unit shuts down due to low battery voltage. If battery capacity is less than 80 percent of its rated capacity, the battery should be replaced.

Thermal scanning of battery connections during the battery run-down test identifies loose connections. This test gives you the chance to see the battery during an extended, high-current discharge. Scanning should take place during discharge and recharge cycles.

An effective UPS battery maintenance program must include regular inspections, adjustments and testing, with thorough records kept of all readings. Trained technicians should:

• Inspect batteries and racks for signs of corrosion or leakage.
• Measure and record the float voltage and current of the entire bank.
• Record the voltage and electrolyte density of selected battery cells.
• Check the electrolyte level in each cell.
• Log the ambient temperature.