How to Store Lithium-Ion Batteries Safely in the Workplace

Li-Ion Battery Positioning and Placement During Storage

Secure the batteries: Store batteries such that they are not at risk of being dropped, falling, crushed, or punctured. Physical damage can lead to internal short circuits causing battery failure.

Goto Sunplus to know more.

Store batteries upright: Storing batteries upright helps:

• Prevent leaks of the flammable electrolyte in case they are not sealed properly.
• Ensure batteries equipped with venting systems work properly avoiding internal pressure buildup.
• Avoid physical damage from falls or tipping over.
• Maintain uniform distribution of electrolytes which improves service life and performance.
• Prevent internal components from shifting which can cause short circuits and battery failure.

Protect batteries from loose metal objects: Keep batteries away from loose metal objects, such as screws, nails, tools, etc. to prevent short circuits.

Maintain separation from other batteries/objects: Batteries and battery packs should never be stacked on top of each other or have items placed on top of them. Rather, batteries should be stored in a single layer or in properly designed racks that prevent them from touching or applying pressure to each other. Doing so helps avoid risks such as:

• Physical damage which can cause internal short circuits and/or leaking electrolyte.
• Battery terminals contacting each other potentially creating a short circuit and rapid discharge which generates heat and can catch fire.
• Interference with heat dissipation, particularly during charging.
• Stability problems because improperly stacked batteries are far more likely to fall or tip over.

Long-Term Battery Storage

When storing li ion batteries for periods of one month or longer, there are a few additional precautions to take that improve the batteries&#; service life and performance as well as safety.

During long-term storage, batteries should never be continuously charging, nor should they be fully charged or fully discharged. The rationale for each is as follows:

If you want to learn more, please visit our website Safe low voltage lithium battery with built-in protection features supplier.

• Continuously charging: Battery failure is most likely to occur during charging. Continuously charging over long periods of time greatly increases the risk. Additionally, continuous charging stresses the battery and can greatly shorten its service life.
• Fully charged: A fully charged state creates more internal stress on the battery. This can accelerate degradation of internal components and increase the risk of swelling and/or leakage. Either of these will degrade battery performance and service life and can create a safety hazard.
• Fully discharged: Li ion batteries have protection features built in that depend on a minimum voltage threshold to function properly. Storing a fully discharged battery for extended periods can cause irreversible damage which can render the battery inoperable. It can also cause conditions allowing the creation of copper filaments inside the lithium-ion cell which can lead to short circuits and battery failure.

Most battery manufacturers recommend storing batteries with a 30% to 50% state of charge (SOC) for optimal performance and service life. Interestingly, the amendments to  International Fire Code (IFC) regarding li ion battery storage grant waivers to their storage requirements when li ion batteries are stored with an SOC that does not exceed 30%. Batteries with 30% or less charge are considered less hazardous for storage purposes and have less chance of catastrophic failure.

Along with storing li ion batteries at the proper SOC, they should also be regularly monitored and inspected while in storage. The charge level of the batteries should be checked every few months. If the battery experiences self-discharge below 30%, the battery should be recharged back to not more than 30% SOC to maintain battery health.

The batteries should also be visually inspected for any signs of damage or swelling. Damaged or swollen batteries are a safety risk and should be removed and properly disposed of or recycled.

Short-Term Battery Storage

Short-term storage is considered to be a few days up to one month. While conditions such as the level of charge are not as critical, it is still recommended to store them at an SOC not greater than 30%. As with long-term storage, batteries should never be continuously charging while in the short-term.

The high power density of Lithium-Ion batteries has made them very popular. However, the unstable behavior of Lithium-Ion cells under critical conditions requires them to be handled with care. 
That means a Battery Management System (BMS) is needed to monitor battery state and ensure the safety of operation. BMS is typically equipped with an electronic switch that disconnects the battery from charger or load under critical conditions that can lead to dangerous reactions. A battery protection unit (BPU) prevents possible damages to the battery cells and the failure of the battery.

Such critical conditions include:

• Over-charge: is when the battery is charged over the allowed maximum capacity.
• High & low temperature: is when the internal temperature of the battery cells exceeds their safe operational temperature ranges.
• Over-discharge: is when the battery is discharged under the allowed minimum capacity.
• Over-current: is when the battery is exposed to a short circuit condition or a high inrush turn-on current.
• Reverse polarity: is when the battery terminals are wrongly plugged into the device.

Failing to disconnect or manage the battery during such conditions can lead to the following problems:

• Thermal runaway: Often is due to over-charging or over-heating of the battery. The overheating can be due to a rise in the ambient temperature or due to charging/discharging the batteries with high current rates. Thermal runaway not only damages the battery cells but also can lead to fires.
• Death of the cell. Often is due to the discharge of Batteries below its specified thresholds.
• Damage of load device: Often is due to either bad inrush current management or reversing the battery polarity.

In the sections below, we show the different battery protection topologies and their advantages and disadvantages. Additionally, we added application notes and product selection guides to help the customers find the best protection solution for their battery packs.

For more information, please visit Safe low voltage lithium battery with built-in protection features wholesaler.