Your Uninterruptible Power Supply (UPS) system is the heart of your back up power. A single poor battery within a UPS battery string creates a risk of downtime for data center functions. Battery failures account for more than half of all UPS breakdowns. Regardless of if the battery system is Valve-Regulated Lead Acid (VRLA), Vented Lead Acid (VLA), or Nickel-Cadmium (NiCad), it is by far the most vulnerable and most failure-prone part of your UPS. This is why routine maintenance of these batteries is critical to make sure backup power is ready when required.

The main concern for a battery system is the environmental status of your UPS system. Undesirable environments may significantly reduce the available service life. Batteries that are too hot or too cold adversely affect the battery's ability to conduct and store energy. It is expected that each 8-10 ° C increase in temperature lowers the battery life in half. Refer to the battery manufacturer's specifications for the suggested operating temperature variation of the battery.

Additionally, it is also important to make sure that the batteries are charging properly. The battery manufacturer's specifications will include a specification for the float voltage. This value may be mentioned for both the full voltage of the battery block itself or a volts-per-cell level. It is essential to make sure that the battery float is readjusted as measured at the input to the battery string to accommodate for line-losses between the UPS and the battery strings. The float voltage should be corrected such that there is an adequate capacity to charge each of the batteries within the string to a value within the battery manufacturer's published range. Undercharging the batteries might reduce the service life of the battery system and overcharging batteries may develop a hazard to your location or personnel.

Approximately once per year, it is advised to perform a visual inspection on your batteries. Any puffing up or corrosion may indicate an adverse condition that may cause untimely failure. When visually inspecting the battery blocks, it is also essential to look at the battery cabinet or rack itself. Any dripping electrolyte may be streaming towards the battery rack/cabinet itself. This could result in corrosion or short circuit to the battery rack/cabinet and create a risk to your critical power and/or personnel.


The general recommendation for maintenance is as follows:


Conduct a visual inspection. Look for wear and deterioration of the batteries, battery rack/cabinet, adjoining cables, connectors, and electrolyte levels (if VLA/NiCad).

Measure the ambient temperature as well as humidity.

Measure the battery float charging current.

Ensure the UPS surrounding is clean and devoid of dust, debris, as well as the electrolyte.

If a battery monitoring system is in place, review the results of the continuous monitoring.



In addition to the monthly checks:

Check the voltage of each cell or battery block.

Check the ambient temperature and negative-post temperature of a minimum of 10% of the cells or battery blocks. It is suggested, but not required, to check all of the cells when possible.

Conductance testing with a Franklin Electric handheld tester or battery monitoring system.



In addition to the monthly and quarterly checks:

Measure and check the torque of all connections.

AC ripple current imposed on the battery.

Interconnecting cable resistance testing.

Regular maintenance will ensure that maximum service life is attained for the UPS battery system. Because of concerns for safety, only qualified personnel should attempt any battery service or maintenance.


Thank you for stopping by and reading this post. Hope this post helps you to understand the importance of battery maintenance.

Stay updated. Stay safe


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