Your Field Service Report Part 1: UPS Batteries

We are all familiar with going to the doctor to get a check up on our health.  At the end of our visit, we typically receive a summary of what the doctor discussed with us, any tests they did, and recommendations they have for us related to those test results. A field service report (FSR) for your UPS system maintenance is similar to a health check for the unit, giving information on the condition and reliability of the UPS. Most UPS field service reports should include the unit information and location, a job description of what is being inspected, what actions were performed and their results, and the recommendations as the result of the job. In the coming weeks, we will break down a UPS service report and cover some of the main items that you should look for.

UPS Service Reports : Batteries

Batteries are the lifeblood of a UPS system. When power fails at your facility, the UPS batteries are what keeps your equipment running until a generator is able to support critical loads or power is restored, provided you have adequate UPS run-time. For our UPS service technicians, testing and inspection of your UPS batteries is one of their priorities.

When looking at a field service report for batteries, we first want to look for a general summary of the batteries being tested. The battery equipment information should tell you:

• The make and model of the batteries
• If the batteries are internal or external to the UPS
• The age of the batteries
• The number of strings of batteries in the UPS

Tracking the age of your batteries can be critical to ensuring proactive replacement before a failure. There are many ways that a UPS battery can degrade overtime, some of the most common include:

• Excessive heat
  • In fact, the IEEE suggests that for every 15F degrees above 77F, the life of a lead acid battery could decline by 50%.
• Incorrect installation, lose connections or manufacturing defects
• Improper charging current
• Excessive gassing
• Plate Separation
• Grid corrosion

During preventative maintenance battery testing, your UPS service provider should be looking for three key areas to be covered:

1. Visual Inspection
2. Testing
3. Proper safety measures in place

Visual Inspection

During a preventative maintenance inspection, your UPS technician should perform a full visual inspection to look for signs of stress, such as swelling or cracking of the battery cells, or corrosion or other distress. They should also clean and verify torque of the terminal connections if needed.  UPS batteries can be prone to thermal runaway and fire if not properly maintained. Sometimes the early signs of risk are visible. To see more about some of these failures see our article on UPS failure.  The technician should also be verifying ambient temperatures in your UPS room or cabinet to ensure longevity of the battery.

Battery Testing

During UPS battery maintenance inspections, a technician is conducting an individual load test on each battery, often while the UPS system is in bypass. During this test, the technician is verifying several items, including:

• Voltage testing- UPS Batteries are tested for voltage to help evaluate battery health. A cells ability to provide the proper voltage is crucial to ensuring proper DC voltage is available for the DC Buss. As a battery degrades, it may show decreased voltage over time and should be replaced.
• Conductance Testing- Once a baseline reference has been set by evaluation the conductance of a string of known good batteries, conductive testing over time can help to see trending performance of a battery.  Conductance is the ability of the battery to conduct current. In batteries that have higher resistance, or  conversely, lower conductance, the ability of the battery to efficiency provide power degrades over time. 
• A/C Ripple- AC ripple is caused by an incomplete suppression of the AC waveform from the input. This residual current can damage the life of a battery as it can cause overcharging or discharge of a cell. High ripple current can accelerate degradation or corrosion on the positive side of a battery, resulting an increased resistance and can cause thermal runaway.

Proper Safety Measures

Observing that battery safety measures are being followed is critical to any battery field service report. Your technician should be checking to see how your batteries are housed, where they are located in or outside the UPS, when they were last replaced, if there is spill containment in place if required, how the batteries can be transported in and out of the facility, if there are replacement parts on-site, if there is safety equipment on-hand to handle the batteries, and a number of other checks.

Run-time tests on UPS batteries are making sure that the battery quality is still good and the run-time is what was originally expected and has not deteriorated. For example, if your original battery run-time was 25 minutes at full load and is now measured at 19 minutes at full load, you are experiencing deterioration.

The key thing with any field service report is to make sure your provider is properly documenting all information pertaining to your report. Clear photographs, date codes, and any specific instructions should be documented clearly and attached to the report to give you the best understanding of the overall “health” of your UPS batteries.

Unsure if your batteries are healthy or ailing? Contact QPS for a preventative maintenance check today. We can help you make sure your UPS batteries are healthy and will provide you the detailed information you need to better understand their health over time.