Let’s take the example of a well-designed preventive maintenance program for the vented lead-acid battery (VRLA) of an uninterruptible power supply (UPS). Like anyone who cares about their money, they bid on several vendors to reduce the cost. But can we make decisions based on cost alone? Are all the vendors who bid really qualified to do the job?
We recently performed preventive maintenance on a unit that was replaced by the vendor that won the bid with the lowest price. After a visual inspection, the technician found that one of the connections had burned out. Upon closer inspection, the battery terminal had also melted.
Upon inspection, the technician found that the connection between the cable and the pole was not properly tightened and was only hand-tight. When the battery is discharged during a power outage, the connections become hot and the wires melt, which can be very dangerous. Fortunately, in this case, the problem was limited to the installation of the battery and did not result in a fire.
Improper installation
Improperly installed batteries are difficult to detect and often go unnoticed until a problem occurs. If an unqualified person replaces the battery, an important step may be overlooked. The inadequacy of these procedures may not become apparent until a serious problem occurs, such as a loss of charge during a power outage or, in the worst case, a fire. Visit also: Maintenance-free dry batteries
To ensure proper installation of the UPS batteries, detailed procedures must be followed by trained and qualified personnel. The following list does not include all the steps necessary to properly install a battery, but it does provide a foundation.
Tested before installation
All batteries should be tested before installation for open-circuit voltage and internal resistance or impedance. This will ensure that the battery to be installed is intact and functional.
Oxidation of the terminals
Oxidation of the terminals should be removed and no antioxidant grease should be applied. The resulting oxidation increases the resistance of the connection between the terminals and the battery poles. This resistance causes heat to be generated which reduces the performance of the battery.
Tightening according to the recommendation
All connections should be tightened according to the manufacturer’s recommendations. The use of a calibrated torque wrench will ensure that the connections are tight and will prevent damage to the battery terminals by over-tightening.
Inspect the battery system
It is very important to inspect the battery system before reconnecting it. This inspection includes a visual inspection and a physical measurement of the system. Voltage should be measured to ensure that the voltage and polarity are correct throughout the battery system. Ground voltage should be measured to ensure that there is no ground fault in the system. A ground fault is an unintended flow of current to the ground that can cause arcing, fire, system damage, alarms, and tripping of the energized circuit breaker.
Double-check the installation
The technician who wired the system and another technician should also visually inspect the battery system before turning it on. Each technician should look for loose connections, missing accessories, and correct batteries configuration. The second technician should double-check the correct installation, which greatly reduces the likelihood of faults going undetected. reduce the likelihood of faults going undetected.
Measuring battery voltage
After restarting the system, take a few more steps to ensure that the battery is functioning properly. The total battery voltage should be measured to determine if the battery is charged to the optimum voltage. Overcharging or undercharging can affect the life of the batteries and lead to other complications. The voltage values of the individual batteries and cells should also be checked. Detecting differences in charge with other batteries in the same system can lead to the early detection of problems and hidden defects. The same applies to checking the impedance of individual batteries. Manufacturers specify limits and tolerances for different batteries models. So it’s important to make sure the battery is within the expected range.
In the last
When choosing a replacement battery supplier, it is important to consider a number of factors, not just cost. Carefully evaluating the qualifications of all suppliers is an important part of the selection criteria. This early preparation not only gives you peace of mind but also saves you money in the long run.
