To determine whether the UPS battery needs to be replaced, a comprehensive analysis should be conducted based on battery performance parameters, equipment status, and actual usage scenarios. The following are specific judgment methods and steps to help you accurately evaluate:
1、 View direct alarm prompts for UPS devices
Display screen/indicator light alarm
If the UPS host detects an abnormal battery, it will display specific fault codes (such as "BATTERY FAILURE" or "LOW CAPACITY") on the LCD screen, or light up a red warning light (such as "battery fault light").
For example, in the Huawei UPS5000-A series, when the battery voltage is abnormal or the capacity is below the threshold, an alarm message will pop up on the LCD interface; If the number of batteries in the Shante CASTLE series is incorrect or the voltage is too low, the indicator light will flash.
Audio alarm
Some UPS systems will emit continuous beeping sounds when the battery fails, and immediate troubleshooting is required.
2、 Measure battery capacity and performance parameters
1. Capacity testing (core indicators)
Professional equipment measurement: Use a battery capacity tester (such as an intelligent load tester) to perform discharge testing on the battery pack, and record the ratio of actual capacity to rated capacity:
Lead acid batteries: If the capacity is below 60% -80% of the rated value (different brands have different thresholds, such as communication base station batteries often using 80% as the critical value), it is recommended to replace them.
Lithium battery: When the capacity is below 80%, the battery life significantly decreases and replacement may be considered.
Simple estimation (without professional equipment):
Disconnect the mains power and let the UPS only be powered by the battery, record the load running time. If the backup time is shortened to 50% -70% of the new battery (such as the original backup time of 30 minutes, now only 15-20 minutes), the capacity may be insufficient.
2. Voltage and internal resistance detection
Voltage detection:
Use a multimeter to measure the voltage of a single battery (lead-acid batteries are rated at 12V per cell, approximately 13.2V when fully charged). If the voltage is lower than 12V when idle or rapidly drops below 10.5V when discharged, it indicates battery aging.
Internal resistance detection:
Lead acid battery: If the internal resistance of a single cell exceeds twice that of a new battery (such as a new product with an internal resistance of 5m Ω, but now with an internal resistance of 10m Ω or more), it may need to be replaced.
Lithium battery: Abnormal increase in internal resistance (such as exceeding 30% of the factory value), significant performance degradation.
An increase in internal resistance is an important indicator of battery aging. Use an internal resistance tester to measure:
3、 Observe the appearance and physical condition of the battery
Lead acid batteries (commonly found in traditional UPS)
Bulging or deformation: If the shell expands or cracks, it indicates a short circuit in the internal electrode plate or electrolyte deterioration, and must be replaced (there is a risk of leakage).
Leakage: There is electrolyte leakage at the sealed part of the battery compartment cover, which corrodes the terminals or connecting wires. It needs to be replaced immediately and the site cleaned.
Terminal oxidation: White/green rust appears on the positive (red) or negative (black) terminals, causing an increase in contact resistance and affecting charging and discharging. If frequent oxidation persists after cleaning, the battery needs to be replaced.
Lithium batteries (such as UPS2000-H series)
Heating or deformation: During normal use, if the temperature exceeds 45 ℃ or the shell bulges, the internal battery cells may be damaged and need to be replaced with a power outage.
4、 Analyze battery usage time and cycle times
Service life
Lead acid batteries: In a 25 ℃ environment, the float charge life is usually 3-5 years. If used for more than 4 years, even if the current capacity is still acceptable, it is recommended to replace them in advance (aging rate accelerates).
Lithium ion battery: The design lifespan is about 5-8 years (with 1000-2000 cycles). If used for more than 5 years, the capacity may naturally decay to below 80%.
Number of charge and discharge cycles
Lead acid batteries: The number of cycles is about 300-500 times. If frequent power outages cause the battery to discharge deeply multiple times, even if it is used for less than 3 years, it may age prematurely.
Lithium battery: When the number of cycles reaches 800 or more, the capacity may drop below 80%, and it is necessary to pay attention to the cycle record (some UPS can be viewed in the menu).
5、 Combining load importance with backup power demand
Critical load scenarios (such as data centers, medical equipment)
If the battery capacity drops to 80% of the rated value, even if it does not reach the alarm threshold, it can be replaced in advance to avoid data loss or equipment failure caused by sudden power outages.
Ordinary scenarios (such as home use, small office)
Can be replaced when the capacity drops to 60% -70%, reducing costs; If the backup time requirement is not high, it can still be used, but regular monitoring is required.
6、 Professional tool assisted judgment (recommended solution)
UPS comes with battery diagnostic function
Some high-end UPS systems (such as Huawei UPS5000-E and Shante 3C3 Pro) support the "battery self-test" function. After starting through the menu, the device will automatically test the battery capacity, voltage, and internal resistance, and generate a status report.
Third party Battery Management System (BMS)
Large UPS systems can be connected to BMS to monitor the voltage, temperature, internal resistance and other parameters of each battery in real time. When a single battery is abnormal, it will automatically alarm and accurately locate the battery that needs to be replaced.
7、 Precautions
Testing safety: When testing lead-acid batteries, it is necessary to wear insulated gloves to avoid short circuits; Before replacing lithium batteries, disconnect the UPS power supply to prevent electric shock.
Principle of whole group replacement: UPS batteries are usually used in groups. If a certain battery is aging, it is recommended to replace the whole group (to avoid overloading other batteries in the group due to the difference in capacity between new and old batteries).
Environmental impact: High temperatures (over 30 ℃) can accelerate battery aging. If the UPS room has poor heat dissipation, even if it is used for a short period of time, it may need to be replaced in advance.
After comprehensive judgment through the above methods, if it is confirmed that the battery needs to be replaced, it is recommended to contact the UPS manufacturer or professional service provider, choose the appropriate battery model (pay attention to voltage, capacity, and size matching), and handle the old battery in a standardized manner (lead-acid batteries need to be recycled, lithium batteries need to be disposed of as dangerous goods).
