When replacing UPS batteries, it is necessary to strictly follow the operating procedures to avoid equipment damage, electric shock, or fire risks caused by improper operation. The following are key precautions and operational points:
1、 Preliminary preparation: Safety and accessory confirmation
1. Power outage and safety protection
Disconnect all power sources:
First, turn off the UPS host, then disconnect the AC input switch and load output switch to ensure that no current passes through.
If it is a large rack mounted UPS (such as a 380V high-voltage system), insulated gloves should be worn and operated by a professional electrician to avoid electric shock.
Release residual charge:
After disconnecting the battery pack, short-circuit the battery terminals (positive and negative poles) to discharge (using a resistive load, direct short circuiting is strictly prohibited), to prevent residual voltage from the capacitor from injuring people.
2. Preparation of accessories and tools
Battery model matching:
Check the original battery parameters: voltage (V), capacity (Ah), size (length x width x height), terminal type (such as M6 screws, plug type).
Lead acid batteries need to pay attention to float charging voltage (usually 13.5-13.8V), while lithium batteries need to be matched with BMS protocol (some UPS only support specific battery management systems).
Tool List:
Insulated wrench (corresponding to terminal screw specifications), multimeter, torque screwdriver (ensure that the terminal tightening torque meets the standard, such as 4-6N · m).
Acid resistant gloves, goggles (lead-acid batteries), fireproof blanket (lithium batteries), and label stickers (recording battery polarity and connection sequence).
3. Environment and Layout Planning
Ventilation and heat dissipation:
The battery cabinet needs to reserve heat dissipation space and avoid direct sunlight or proximity to heat sources (the optimal temperature for lead-acid batteries is 25 ℃, and for lithium batteries it is 15-25 ℃).
It is prohibited to replace lithium batteries in enclosed spaces (to prevent the accumulation of flammable gases).
Installation direction:
Lead acid batteries need to be installed upside down (do not place on the side to avoid electrolyte leakage), while lithium batteries can be installed according to the design direction (refer to the instruction manual).
2、 Replacement operation: sequence and connection specifications
1. Dismantling of old batteries (taking a series connected battery pack as an example)
Tag connection order:
Use stickers to label the positive (+), negative (-), and series sequence of each battery (e.g. "positive pole of battery 1 → negative pole of battery 2"), to avoid reverse connection during installation.
Disconnect section by section:
Starting from the end of the battery pack (the negative terminal of the last battery), use an insulated wrench to unscrew the terminal screws and remove the connecting wires in sequence to avoid touching the positive and negative terminals of adjacent batteries at the same time (to prevent short circuits).
Remove the old battery:
When handling lead-acid batteries, handle them gently and avoid tilting them beyond 45 degrees; Lithium batteries should avoid compression and collision (especially soft pack batteries).
2. Installation of new battery
Pre assembly and testing:
First, measure the voltage of the new battery in a single section (lead-acid battery ≥ 12.6V, lithium battery ≥ 3.6V), and ensure that the internal resistance consistency deviation is less than 5% (for the same group of batteries).
Arrange the batteries in the order marked, ensuring that the terminal directions are consistent and the spacing is even (for easy wiring).
Series connection:
Starting from the positive pole of the first battery, connect the negative poles of the next battery in sequence with connecting wires to ensure that the terminals are securely fastened without looseness (a small amount of Vaseline can be applied to prevent oxidation).
The lithium battery pack needs to be connected to both the temperature sensor line and the BMS communication line (if any) to avoid missing connections that may cause UPS to be unable to recognize the battery status.
3. Connect to the UPS host
Polarity confirmation:
Connect the positive pole of the battery pack to the "BAT+" terminal of the UPS, and the negative pole to the "BAT -" terminal. Do not connect it in reverse (it will burn out the inverter and charging module).
Power on in stages:
Connect the battery pack first, then close the battery switch and observe if the UPS panel displays "BATTERY OK".
Wait for 5-10 minutes for UPS to complete battery initialization (identifying parameters such as capacity and internal resistance), and then gradually restore mains power and load.
3、 Testing and recording: Ensure proper functionality
1. Charging test
Close the mains switch and observe if the UPS has entered charging mode (the charging indicator light is on and displays "CHARGING").
Lead acid batteries need to be float charged for at least 24 hours, while lithium batteries need to be charged to 100% (some UPS supports fast charging, time needs to be confirmed).
Measurement of charging voltage: The total voltage of the lead-acid battery pack should be the float charging voltage of a single cell multiplied by the number of cells (e.g. 16 cells x 13.5V=216V), and the voltage of the lithium battery pack should comply with the BMS set value.
2. Discharge test
After being fully charged, disconnect the mains power and let the UPS run with 30% -50% rated load. Record whether the actual discharge time reaches 80% or more of the nominal value.
Observe voltage fluctuations during discharge: The voltage of a single lead-acid battery should not be lower than 10.5V, and the voltage of a single lithium battery should not be lower than 3.0V (to avoid overdischarging).
If there is a voltage drop, abnormal noise or UPS alarm during the test, immediately cut off the power and check if the connection is loose or the battery is damaged.
3. System parameter updates
Some UPS systems require manual reset of battery counters or input of new battery capacity (such as APC Smart UPS, which needs to be set through software) to ensure accurate battery life calculation.
Record the replacement date, battery model, serial number, and establish maintenance records (for easy tracking of lifespan).
4、 Safety and Environmental Protection: Risk Prevention and Compliance Handling
1. Response to hazardous scenarios
Lead acid battery leakage:
If the electrolyte comes into contact with the skin, rinse with plenty of water; If it splashes into the eyes, seek medical attention immediately.
Leakage batteries need to be collected in acid resistant containers to avoid contaminating the ground (baking soda can be sprinkled to neutralize the acidity).
Lithium battery caught fire:
In the initial stage, use dry powder fire extinguishers or fire blankets to extinguish the fire, and strictly prohibit using water (which may cause violent reactions with lithium metal).
If the fire gets out of control, evacuate immediately and call the police to avoid inhaling toxic smoke.
2. Disposal of waste batteries
Lead acid batteries: They are classified as hazardous waste and must be handed over to qualified recycling companies (such as Greentown and Tianneng Recycling). It is prohibited to mix them with household waste.
Lithium batteries: It is necessary to distinguish between ternary lithium and lithium iron phosphate, and recycle them through professional channels (such as CATL Bangpu cycle) to avoid punctures or exposure to fire sources.
5、 Common Error Avoidance
Wrong operation, risk consequences, correct approach
During live operation, if there is a short circuit, fire, or contact with electricity, all power sources must be disconnected, and the operation must be carried out after verifying the electricity
The difference in internal resistance caused by the mixed use of new and old batteries leads to overload and scrapping of the new batteries, and the entire set is replaced to ensure consistency in batches
The connecting wire is not tightened and the contact resistance is high, causing heating and burning of the terminal. Use a torque wrench to tighten it to the specified torque
Neglecting the polarity marking of the battery resulted in the UPS motherboard burning out. Mark each section during disassembly and double check during installation
Untesting the failure of a new battery directly online can cause a power outage accident. Charging and discharging tests and parameter settings must be completed
Summary: Key step mnemonic
Cut off the power and conduct electrical testing to prevent electric shock. Mark the polarity and remove old parts: safety first, avoid wiring confusion.
New electric matching parameters are complete, with tight connections and no loose points: ensure consistent models and secure terminals.
Check the charging and discharging test time, reset the parameters and record them in the file: verify performance and keep maintenance records.
Seeking qualifications for hazardous waste treatment, keeping in mind safety regulations, environmental compliance, and risk prevention.
Following the above points can ensure the safe and efficient replacement process of UPS batteries, maximize the service life of new batteries, and ensure the stable operation of the power supply system. For large data centers or complex UPS systems, it is recommended to have vendor technicians or certified electricians operate to reduce the risk of human error.
