In the daily operation and maintenance of Uninterruptible Power Supplies (UPS), battery string adjustment is a critical procedure that impacts power supply stability and equipment lifespan—especially for extended-run UPS models with external battery packs. A proper adjustment process ensures the battery and UPS system operate in harmony; conversely, incorrect operation may lead to equipment malfunctions, battery damage, or even safety hazards. This article provides professional guidance covering general operating steps, common pitfalls, and risk prevention measures.

I. UPS Battery String Adjustment: Preparations and Core Prerequisites

Before initiating the adjustment, two key preparatory tasks must be completed to ensure the subsequent process is safe and effective.

1. Verify Model Compatibility and Battery Parameters

First, confirm whether the UPS model supports battery string adjustment: standard UPS (with built-in fixed battery packs) typically do not support adjustment, while only extended-run UPS (with external expandable battery packs) offer parameter configuration functionality. Refer to the device’s User Manual to check for the "Battery Parameter Configurable" label and the supported adjustment range (e.g., most industrial-grade extended-run UPS support 16–20 pieces of 12V batteries in series).

Meanwhile, record the core battery parameters in advance:

• Voltage per battery cell (common values: 12V, 6V, 2V);

• Planned total number of batteries in the string (must fall within the model’s supported range);

• Battery pack connection method (single string in series or multiple strings in parallel).

2. Switch the Device to a Safe Operating State

To avoid interrupting power supply to loads or damaging equipment during operation, switch the device state as follows:

• Switch the UPS to "Bypass Mode" or "Standby State": Via the device’s operation panel or monitoring system, disconnect the UPS’s inverter output to the load, ensuring the load is powered by the mains bypass (confirm the bypass indicator light is on);

• Disconnect the battery pack: Turn off the battery circuit switch and unplug the connection cable between the battery pack and the UPS battery interface to prevent module damage caused by short circuits or accidental contact during operation.

II. General Adjustment Process: From Parameter Setting to Validation

While the operation interfaces of UPS from different manufacturers may vary, the core logic remains consistent. Below are the general adjustment steps:

1. Access the Battery Setting Menu

• Models with physical buttons: Press and hold a combination of keys (usually "Confirm + Up/Down Adjustment Keys") for 5–10 seconds until the "Battery Parameter Configuration" screen appears; alternatively, navigate through the path "Menu → System Settings → Battery Management".

• Smart monitoring models: Via the device’s LCD touchscreen, find the "Battery Configuration" option in the main menu; if remote management is supported, log in via supporting software (e.g., the manufacturer’s operation and maintenance platform) to access the parameter setting interface.

2. Configure Core Parameters

Enter the following key parameters accurately based on the actual battery configuration:

• Number of batteries per string: For a single series-connected battery string, directly enter the total number of batteries (e.g., enter "18" for 18 pieces of 12V batteries in series);

• Number of battery cells (required for some models): Since some UPS calculate based on "cells" (1 cell = 2V), conversion is necessary—12V battery = 6×2V cells, 6V battery = 3×2V cells, 2V battery = 1 cell (e.g., 16 pieces of 12V batteries = 96 cells, so enter "96");

• Additional parameters: For multiple parallel battery strings, set the "Number of Battery Strings" (e.g., enter "3" for 3 parallel strings) and fill in the capacity (Ah) per battery cell to ensure the UPS accurately calculates backup time.

3. Save Settings and Verify Effectiveness

• After entering the parameters, press the "Confirm" key to save. Some models require entering an administrator password (default passwords are usually "0000", "1234", or specified in the manual);

• Perform a complete power-off restart of the UPS: Turn off the input mains switch, wait 30 seconds, then power on again. Reconnect the battery pack simultaneously;

• Verify parameters: After the UPS completes self-test (typically 3–5 minutes), access the battery parameter interface to confirm the displayed number of batteries, capacity, and other information matches the actual configuration, with no "Parameter Mismatch" alarm.

III. Common Pitfalls and Risks: Issues to Avoid

During adjustment, the following four types of issues are most likely to cause malfunctions and require special attention:

1. Incorrect Parameter Conversion: 12V Battery ≠ 1 Cell

Some users mistakenly set 12V batteries as "1 battery = 1 cell", leading to errors in UPS charging voltage calculation. If the model requires entering "number of cells", multiply the number of 12V batteries by 6 (e.g., 20 pieces of 12V batteries = 120 cells). This error can result in:

• Insufficient charging voltage: Batteries are chronically undercharged, accelerating capacity degradation;

• Excessive charging voltage: Batteries are overcharged and swell, potentially causing leakage or fire risks.

2. Exceeding the Model’s Supported Battery String Range: Irreversible Hardware Damage

• Too many batteries: If the model’s maximum support is 20 pieces of 12V batteries but 24 are configured, the UPS battery management module will burn out due to overloading, and the damage is usually irreversible;

• Too few batteries: If the minimum requirement is 16 batteries but only 12 are configured, "Battery Undervoltage Protection" will be triggered. When mains power fails, the UPS cannot switch to battery power and will shut down immediately.

3. Omissions in Operational Procedures: Dual Risks to Safety and Stability

• Operating without switching to bypass: Adjusting parameters while the load is running may cause the UPS to restart due to instantaneous data conflicts, resulting in data loss for critical equipment such as servers and medical devices;

• Failing to restart after power-off: Some UPS require a complete power-off to refresh the battery management logic. Saving settings alone leads to "false parameter activation"—the interface shows new parameters, but actual charging/discharging still follows old parameters, shortening battery life over time.

4. Ignoring Derating Risks: Sudden Drop in Load Capacity

When the configured number of batteries is lower than the model’s rated string count (e.g., 16 instead of the rated 20), most UPS will automatically reduce the inverter output power (derating ratio = actual number of batteries / rated number of batteries, e.g., 16/20 = 80%). If this is overlooked and the original load is maintained, "Overload Protection" will be triggered, causing the UPS to shut down.

IV. Key Considerations: Ensuring Long-Term Stable Operation

• Follow the manual: Menu paths and parameter definitions vary greatly across models. All operations must be performed in accordance with the device’s User Manual—do not replicate procedures from other brands;

• Load testing: After adjustment, simulate a mains power outage (turn off the input switch) and observe the UPS operating with the load for over 30 minutes to confirm no "Battery Fault", "Undervoltage", or "Overload" alarms;

• Cable matching: For multiple parallel strings, thicken the main battery cables based on total current (e.g., for 3 parallel strings of 100Ah batteries, the cable cross-sectional area should be 2 times larger than that for a single string) to prevent overheating and burning of cables.

Conclusion

UPS battery string adjustment is not a simple "number input" process but a systematic operation involving parameter conversion, hardware matching, and procedural compliance. By following the logic of "verify compatibility → switch to safe state → configure parameters accurately → validate effectiveness" and avoiding risks such as conversion errors and range violations, you can ensure the UPS and batteries work synergistically to provide reliable uninterrupted power for loads. If in doubt about the operation, consult professional maintenance personnel to prevent equipment damage caused by improper operation.