(1) Internal chemical stability 

Lithium batteries contain active chemicals inside, mainly the movement of lithium ions between the positive and negative electrodes. If the battery is in extreme conditions for a long time (e.g., full or low charge), it will cause the balance of internal chemical reactions to be disrupted, accelerating battery aging or even failure. 

(2) Avoiding capacity loss 

The pressure inside the battery increases when it is fully charged, and being in this state for a long time will lead to changes in the structure of the electrode material and a decrease in capacity; when the battery is low, lithium batteries are easy to over-discharge, leading to the failure of the materials inside the battery, which makes it impossible to recharge in serious cases. 

(3) Prevent excessive self-discharge 

Even if the lithium battery is not used, it will be self-discharged, resulting in a gradual decrease in power. If stored for a long time and the charge is too low, the battery may enter an over-discharged state. In this state, the voltage drops to a certain level will trigger the protection mechanism, making the battery unable to be charged or used, or even fail completely. 

(4) Heat Sensitivity 

High temperature will lead to electrolyte decomposition, increase the self-discharge rate, and may trigger battery expansion, leakage or even explosion; low temperature will reduce the efficiency of the chemical reaction of the battery, affecting the battery's energy storage capacity and life.  Improper storage of lithium batteries, especially at high temperatures, humidity or mechanical damage, may lead to safety hazards, such as short circuit, combustion or explosion. Lithium batteries contain flammable substances inside, and if the battery malfunctions or the material ages, it may trigger an internal short-circuit and generate thermal runaway phenomenon, leading to fire or explosion. Therefore, a safe storage environment is essential.

2、Can't the BMS that comes with the  lithium battery protect the battery during storage?     

(1) Self-discharge cannot be completely avoided 

Although the BMS can protect the battery during use, the battery will naturally self-discharge during long-term storage, and the BMS itself will also consume the battery power (i.e., “static power consumption”). Over time, the cells will still self-discharge, even if the BMS protection is enabled.     

(2) Limited Temperature Management 

The BMS can provide over-temperature protection while the battery is in use, but it cannot actively control the temperature of the storage environment while the battery is in storage. If the battery is exposed to high or extreme temperatures for an extended period of time, the BMS does not actively cool or heat the battery to prevent degradation caused by improper temperatures.     

(3) Inability to repair chemical degradation

The internal chemistry of lithium batteries will gradually and slowly deteriorate during long-term storage, especially when stored at full charge or too low a charge. the BMS is unable to prevent or repair this chemical degradation, it is mainly used to monitor and prevent extremes in battery voltage, temperature and current, rather than altering the internal chemical state of the battery. 

(4) Static Power Consumption Problem

The BMS consumes a small amount of power even when it is in a dormant state. This means that the BMS itself slowly drains energy from the battery even when not in use. If lithium batteries are stored for a long period of time and the charge level is not checked regularly, the constant power consumption of the BMS may eventually cause the battery to enter an over-discharged state, which can lead to irreversible damage. 

A BMS can provide a degree of protection during storage, but it cannot completely protect against the risks posed by self-discharge, temperature changes and chemical degradation of the battery. 

 3、How should I store my lithium batteries if I don't use them for a long time?

(1) State of charge 

Lithium batteries should be kept in the 30%-50% charge range. This is because a full charge or too low a charge will adversely affect the health of the battery. 

(2) Ambient temperature 

The storage environment should be kept between 10°C and 25°C, avoiding high or extreme low temperatures. High temperatures accelerate battery aging, while low temperatures may cause the internal chemical reaction of the battery to slow down. 

(3) Dry environment 

Choose a dry, well-ventilated place and avoid humid environments, as moisture may trigger internal corrosion or short-circuit of the battery. 

(4)Regularly check the power level

When lithium batteries are stored for a long period of time, it is recommended to check the power level every 3-6 months. If the power level is lower than 30%, it should be properly charged to 30%-50% before further storage.