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How can I store lithium-ion cells and what is the self-discharge rate?

Maximize the storage of batteries, understand self-discharge rates, and how environmental factors affect storage duration.

Rafael Fernando Ancheta III avatar
Written by Rafael Fernando Ancheta III
Updated over 7 years ago

Storage

Several months of storage for lithium-ion cells will lead to minimal deterioration if general guidelines are followed. The bottom-line is to avoid under-voltage conditions. The environment should be controlled to prevent high temperature, humid, wet and other corrosive conditions.

Self-discharge

Source: TU München

A general rule to determining the self-discharge rate of li-ion cells we use is the following:

  • 5% in 24 hours

  • 1–2% per month + ~3% for safety circuit

For customers which have the least tolerance for self-discharge we recommend use of the Li/SoCl2 chemistry.

Maximum storage time

For the most part, the maximum time for 18650 storage before recharge is about one year. Although it is recommended to do this based on a voltage condition or every 1-3 months.

Data sheet examples

The following are three examples of storage data obtained from the Product Specifications. Most commodity cells fall within these ranges.
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Optimize storage environment to prevent deterioration

Temperature

Temperature limits vary between cells and Product Specifications should referenced and observed. The self-discharge of all battery chemistries increases with temperature.

For most li-ion cells, a good storage temperature should be closer to 25°C (77°F) or a somewhat lower. The closer you are to an optimal temperature, the longer you will be able to store your batteries without "topping up" and recharging them.
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The maximum temperature for storage should never exceed +60°C (140°F). It is better to store in a cold environment, than a hot one.  

Voltage

Beyond preserving performance, the goal is to prevent under-voltage conditions for cells which will damage them. Voltage cut-off or ends are stipulated in the Product Specifications.

If you are intending long term 18650 storage, a storage charge closer to e.g. 50% of usable capacity (~3.7V) rather than 100% (4.2V) will prevent faster battery degradation. Also note a partially charged cell is less prone to failure than a fully charged one.  

Battery pack 

If a battery pack goes into under-voltage conditions the pack may be disabled. After receiving battery packs from Voltaplex you should charge them. Disabled packs can sometimes be woken up but may require special equipment.
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