To determine whether UPS batteries require charging and discharging maintenance, a comprehensive evaluation should be conducted from multiple aspects such as battery status, usage time, and performance indicators. The following are specific judgment methods and maintenance suggestions:
1、 Observe the appearance and physical condition of the battery
Appearance inspection:
Check if the battery casing has bulges, deformations, leaks, or cracks. If such a situation occurs, it may be due to abnormal chemical reactions inside the battery, and immediate charge and discharge testing or replacement is required.
Inspection of connecting components:
Check if the battery terminals are oxidized, loose, or overheating (you can lightly touch the terminals with your hand, if the temperature is significantly higher than room temperature, there may be poor contact). Poor contact can affect the charging and discharging efficiency. It is necessary to clean the terminals and tighten the connections before evaluating whether maintenance is needed.
2、 Reference battery usage time and lifespan
Initial maintenance of new batteries:
Newly installed UPS batteries are usually recommended to undergo initial charge and discharge maintenance 3-6 months after being put into use to activate the active material on the battery plates and extend their lifespan.
Regular cycle maintenance:
Sealed lead-acid batteries (such as VRLA): It is recommended to perform charging and discharging maintenance every 6-12 months. If the ambient temperature is above 25 ℃ (such as poor heat dissipation in the computer room), the maintenance cycle should be shortened to 3-6 months (high temperature will accelerate battery aging).
Nickel cadmium batteries: can be maintained every 12-18 months, but care should be taken to avoid excessive discharge.
3、 Detect battery voltage and capacity
Static voltage measurement:
Disconnect the UPS load and let the battery stand still (1-2 hours), then use a multimeter to measure the voltage of a single battery:
Lead acid battery: The standard voltage for a single cell is 12V. If the voltage is lower than 12V (such as below 11.8V) when it is idle, there may be power loss or aging, and charging and discharging recovery is required.
When multiple batteries are connected in series (such as 12 batteries connected in series to form a 48V system), if the voltage of one battery is significantly lower than that of the other batteries (the difference exceeds 0.3V), it indicates that the battery is unbalanced and needs to be maintained or replaced separately.
Load voltage test:
Place the UPS in battery discharge mode (disconnect mains power) and observe the rate of voltage drop in the battery pack:
Under normal circumstances, the voltage should slowly decrease. If the voltage drops sharply during the initial discharge stage (such as a 12V battery dropping below 10.5V within 10 minutes of discharge), it indicates that the battery capacity has significantly decreased and needs to be charged and discharged for maintenance or replacement.
Capacity testing (recommended professional equipment):
Use a battery capacity tester (such as an intelligent load tester) for discharge testing, set the discharge cut-off voltage (such as 10.5V per lead-acid battery), record the actual discharge time and capacity:
If the measured capacity is lower than 80% of the rated capacity, it indicates that the battery performance has deteriorated and needs to be restored through charging and discharging cycles (some new and old batteries can improve their activity through 3 charging and discharging cycles); If it is below 60%, it is recommended to replace it.
4、 Monitor UPS system alarms and parameters
UPS panel alarm:
When UPS displays alarms such as "battery failure", "low battery voltage", "abnormal battery charging", etc., it is necessary to immediately check the battery status and perform charging and discharging maintenance.
5、 Environmental and load factor assessment
Temperature impact:
The optimal working temperature for batteries is 20-25 ℃. If the ambient temperature remains above 30 ℃ for a long time, the battery life will be shortened by more than 50%. At this time, even if it is not yet the maintenance period, the voltage and capacity should be checked every 3 months, and charging and discharging should be carried out if necessary.
Load situation:
If the UPS is in a light load state for a long time (load rate below 30%), the battery may cause the plates to sulfide due to shallow charging and discharging. It is recommended to regularly (such as quarterly) run the UPS with a load of 50% -80% and conduct discharge tests.
If the load fluctuates frequently or there is an impact load (such as starting a motor or air conditioner), it may cause instantaneous high current discharge of the battery, and maintenance frequency needs to be increased.
6、 Operation suggestions for charging and discharging maintenance
Charging process:
First, use UPS to perform normal float charging (13.5-13.8V) on the battery for 24 hours; If the battery voltage is low, the equalization mode (14.4-14.7V) can be enabled, but the equalization time should not exceed 8 hours to avoid overcharging.
Discharge process:
Disconnect the mains power and discharge the UPS with load until the voltage of a single battery drops to 10.5V (lead-acid battery) or the set cut-off voltage. Record the voltage drop curve during the discharge process.
It is recommended to control the discharge depth within 50% -80% (to avoid excessive discharge), and charge immediately after discharge for at least 12 hours.
matters needing attention:
Someone must be on duty during discharge to avoid UPS power outage caused by premature battery depletion.
If the capacity cannot be restored after multiple charging and discharging cycles, or if the voltage difference between a single battery exceeds 0.5V, the entire battery pack needs to be replaced (to avoid performance drag caused by mixing old and new batteries).
Summary: Maintain trigger conditions
When the following situations occur, charging and discharging maintenance must be carried out:
The battery has been used for more than 6 months without maintenance;
The voltage of a single battery is lower than 12V (lead-acid) or the voltage difference exceeds 0.3V;
UPS alarm indicates battery abnormality;
The measured capacity is less than 80% of the rated capacity;
The environmental temperature is consistently above 25 ℃ or the load is abnormal.
By regular inspection and scientific maintenance, the lifespan of UPS batteries can be effectively extended, avoiding the risk of power outages caused by battery failures.
