How to Extend the Service Life of a Power Bank? The Science of Correct Charging and Storage

The service life of a power bank is directly related to the attenuation rate of its lithium – polymer battery. Most users neglect charging habits and storage methods, resulting in problems such as a sudden drop in capacity and slow charging/discharging of the device within 1 – 2 years. The following will popularize the scientific methods to extend the life of a power bank from four dimensions: battery aging mechanism, charging/discharging protection, temperature impact, and long – term maintenance.

I. Aging Mechanism of Lithium – Polymer Batteries: Cycle Count and Capacity Attenuation

The lithium – polymer battery is the core of a power bank. Its aging is essentially the chemical loss of electrode materials, and the cycle count and depth of charge/discharge are the key factors affecting the attenuation rate.

• Definition of Cycle Count: According to industry standards, “1 cycle” refers to the process where a power bank is discharged from a full charge (100%) to 20% and then recharged (not from 100% to 0%). Tests show that a high – quality lithium – polymer battery can still maintain 80% of its initial capacity after completing 500 standard cycles; after 1000 cycles, the capacity will drop to about 60% of the initial value, and at this time, the power bank will show the phenomenon of “charging quickly but draining even faster”.
• Impact of Charge/Discharge Depth: Deep charging and deep discharging (discharging to below 10% and then recharging) will accelerate attenuation. Comparative experiments show that a power bank that is discharged to 5% each time before recharging has a remaining capacity of 65% after 300 cycles; while a device that is recharged when the power is used up to 20% still has a remaining capacity of 78% after the same number of cycles. Frequently using the power bank until it shuts down automatically in daily use will cause the electrode structure to shrink and expand violently repeatedly, and the capacity may decrease by 10% within 3 months.

II. Avoid Over – Discharging/Over – Charging: The Key Role of the BMS Management System

Over – charging (remaining at 100% power for a long time) and over – discharging (power below 5%) are the main causes of irreversible damage to the battery, and the BMS (Battery Management System) is the “protective barrier” of the power bank.

• Over – Charging Protection of BMS: The BMS of a high – quality power bank will reduce the charging current when the power reaches 98% and cut off the input when it reaches 100%, preventing the battery from being in a high – voltage state for a long time. Tests show that after a power bank without BMS is continuously over – charged for 4 hours, the battery expansion rate reaches 15% and the capacity is permanently lost by 20%; a device with BMS that is continuously charged for 24 hours has a stable power of 100% ± 1% and no battery expansion.
• Over – Discharging Protection of BMS: When the power of the power bank drops to 3%, the BMS will automatically cut off the power to prevent electrode crystallization caused by over – discharging. In an experiment, when a power bank was forced to discharge to 0% (bypassing the BMS), after only 3 times, the battery capacity dropped from 10000mAh to 7200mAh, and the charging speed decreased by 40%; while a device that relies on the BMS to cut off power normally has a capacity loss of less than 5% in 6 months under the same frequency of use.
• Purchasing Details: A high – quality BMS must have a “three – charge and three – discharge” calibration function (automatically completing 3 shallow charge and discharge cycles when first used), and the protection response time should be ≤ 0.01 seconds; the BMS of some low – cost power banks only supports basic power cutoff and has no current regulation function. Therefore, priority should be given to products marked “complying with the IEC 62133 safety standard”.

III. Impact of Temperature on Battery Health: Optimal Environment for Use and Storage

Lithium – polymer batteries are sensitive to temperature. Excessively high or low ambient temperatures will accelerate chemical loss, so the temperature range for use and storage must be strictly controlled.

• Operating Temperature: The optimal operating temperature is 20 – 25℃, at which the battery charging and discharging efficiency reaches 95%. When the temperature exceeds 35℃, the electrode reaction speed accelerates during charging. Tests show that when a power bank is charged in an environment of 38℃, its capacity loses 8% more after 50 cycles than when charged in an environment of 25℃; if the temperature is below 0℃, the discharge capacity will drop sharply — at – 5℃, the actual usable capacity of a 10000mAh power bank is only 7500mAh, and forced discharge will cause the battery to freeze internally.
• Storage Temperature: For long – term storage, the temperature should be controlled at 10 – 20℃, and the humidity should be ≤ 60%. In a comparative experiment, fully charged power banks were stored in an environment of 30℃ and 15℃ respectively. After 3 months, the capacity of the group stored at 30℃ remained 82%, and that of the group stored at 15℃ remained 91%; if stored in an environment above 40℃ (such as in a car in summer), the battery may bulge within 1 month, and the capacity loss exceeds 15%.

IV. Maintenance Tips When Not in Use for a Long Time: Maintaining 50% Power

Most users store their power banks “fully charged” or “empty” when they are not in use for a long time. Both methods will accelerate aging, so the principle of “half – charge storage” must be followed.

• Power Maintenance Standard: Before long – term non – use, the power should be charged to 50% ± 5%. Tests show that a power bank stored at 100% power for 6 months has a remaining capacity of 78%; the same model of device stored at 20% power has a remaining capacity of 75%; while the device stored at 50% power still has a remaining capacity of 89%. Because at 50% power, the internal voltage of the battery is in an “intermediate state”, and the chemical activity of the electrodes is the lowest, resulting in the slowest loss.
• Regular Power Supplement: Even if it is idle for a long time, it is necessary to supplement the power once every 3 months to maintain the power between 40% and 60%. If the power bank is not charged for 6 months, it may trigger the BMS lock due to “low voltage”, requiring activation by a dedicated device. In some severe cases, the battery may become permanently unusable.
• Storage Details: It should be kept away from metal objects (to avoid short circuits) and placed in a dry dust – proof bag. It must not be stored together with corrosive substances such as cosmetics and cleaning agents. If the power bank has an LED display, it is necessary to confirm that it is turned off before storage (to avoid standby power consumption).

In conclusion, extending the service life of a power bank requires focusing on the three key points of “scientific cycling, relying on BMS, and temperature – controlled storage”: avoid deep charging and deep discharging, give priority to products with a complete BMS, control the temperature for use and storage, and maintain 50% power when idle for a long time. By following this method, most power banks can be used stably for more than 3 years, with the capacity attenuation controlled within 20%.