How to Best Store Lithium Batteries and Cells

If lithium-ion batteries are not stored properly, they could lose capacity, have a shortened lifespan, or even start a fire. Some best practices for storing lithium batteries run contradictory to intuition. For example, If you are storing batteries that you expect to be able to use later, it may make sense to store them fully charged but this is not the case. Another common battery storage mistake is storing batteries in an area that has a temperature that is just fine for them 90% of the year, the 10% of the year that it is much hotter in that room can take several years of life off of your battery. This is why it's important to know how to safely store lithium batteries and cells. 

If you are storing batteries for any amount of time and an animal or some other disturbance tips over whatever structure or box you are storing your lithium batteries and cells in, when they hit the floor you could be in for fireworks depending on several factors. Long-term safety and storage are often overlooked because of the heavy focus on the construction, operation, and many other aspects of lithium-ion batteries. 

It's best to store lithium batteries and cells at 60 to 70 percent of their maximum charge voltage as storing them fully charged will damage the cells internally over time. To safely store lithium batteries and cells, keep the terminals covered so there can’t be any unexpected shorts. Store lithium batteries and cells in a box or carton of some sort so they can’t be crushed. Make sure that the temperature of the room you plan on storing your lithium batteries and cells in does not exceed or go below the temperature range that is safe for the chemistry of whatever lithium cells you are storing. Don’t store your lithium batteries and cells on a surface that could fall over or easily get damaged to the point that it falls. 

In this article, we will go over how to safely store lithium batteries and cells. We will go over some things that you should avoid and some best practices to store your lithium batteries.

How To Safely Store Lithium Batteries And Cells

Keep The Terminals Covered

When storing lithium-ion batteries and cells, the terminals should be covered to prevent any possibility of a short. If you are storing lithium battery packs, it’s a good practice to put tape over the connections to make sure they don’t bump into anything conductive that could cause a short. 

Purpose-Built Battery Containers

There are several storage solutions on the market that take the dangers of lithium battery and cell storage into consideration. Generally, what is sought after in a battery box or bag is a fireproof rating. Because of that, there exists a wide selection of fireproof battery boxes and battery bags. 

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Don’t Let Stored Lithium Ion Batteries Get Crushed

Make sure to store your batteries in a way that prevents the possibility that they have a large amount of pressure applied to them. For example, if you are storing your batteries on a shelf, you can put them in a closed box on a shelf. That way the weight from anything that is placed on top of the box is not transmitted to the lithium batteries. 

Store Lithium Batteries And Cells In The Proper Environment

Lithium batteries should always be stored in a dry, well-ventilated, environment that has an ambient temperature of somewhere between 40F and 80F. The safest way to store lithium batteries and cells is to store them in such a way that they never receive direct sunlight. Heat is bad for batteries and heating and cooling cycles cause other unwanted effects that degrade the cells over time. 

Another thing to consider when storing lithium batteries and cells is their location relative to sources of heat. Things like furnaces, hot water heaters, and even HVAC vents can, over time, damage lithium-ion batteries that are intended to be stored for long-term use. 

Store Lithium Batteries And Cells On A Stable Surface

It's critical to ensure that you are not storing lithium-ion batteries and cells on a structure that could be easily tipped over or otherwise caused to collapse. If a lithium-ion battery falls from a high distance, there is a high likelihood that the damage will result in an internal short. An internal short happens, well, internally to the cell.

This means a BMS if installed, can't do anything about it. If the damage is bad enough, the cell could overheat to the point of thermal runaway. Then, the next thing you know your house is burning down because your cat knocked a box of batteries off of a tall cabinet. To avoid unlikely but totally possible things like that, it's best to know how to safely store lithium batteries and cells.

While it’s true that most of the time you will just end up with a few dented cells that won't fully charge, there is a real possibility that one of those dents goes deep enough to cause a cell to overheat. Rarely, those cells can overheat so badly that they either directly catch on fire or combust a material that is touching the cell. 

Store Lithium Batteries And Cells At The Proper Voltage

It’s easy to assume that the best voltage to store a battery at would be fully charged. After all, you would want the battery to be fully charged when you used it again and all lithium-ion batteries have some degree of self-discharge, so why not store lithium-ion batteries fully charged?

When you aren't using your lithium batteries and cells, they should be brought to around 60 to 70% of their maximum charge voltage. In the case of NMC lithium-ion, this is about 3.8V. This is because the chemistry in the lithium-ion cells is more active in the higher ranges of the cell’s voltage. This causes damage to the cell and increases internal resistance over time. 

How Do You Store Lithium Batteries Long Term?

Long-term is relative, but this generally means several years. If you are going to store lithium batteries and cells for several years, then a climate-controlled environment is required. The batteries need to be kept at no higher than a 70% state of charge, and they need to be stored in a container or some other apparatus that keeps them safe and separate from their surroundings. 

Conclusion

All sorts of things can happen that could lead to stored lithium batteries and cells either losing capacity or getting damaged. In a worst-case scenario, improperly stored lithium batteries and cells can lead to a fire. In a less dramatic case, improperly storing batteries can make it so they don’t work when you most need them to. Another common lithium battery storage miscalculation is temperature. A room that has a temperature that won't hurt a battery for most of the year may have a battery-killing temperature for the rest of the year. So, don’t let the illusion of a comfortable room put your battery in an unideal situation. 

Storing batteries on tall, narrow structures is not advised unless that structure is bolted down or otherwise very stable. This is because if the shelf or other structure that you are storing your batteries on were to fall over, an unpredictable amount of physical damage will occur to the cells, leaving you with an above-zero chance of dealing with an unattended thermal runaway. 

The best way to safely store lithium batteries and cells is to keep terminals, electrodes or leads covered so that no unexpected shorts can occur. Make sure to compartmentalize your batteries by storing them in a box or carton of their own. Make sure they can't get crushed by current or new things that may be placed next to them, and don't place anything on the batteries that you are storing. Don’t store your lithium batteries and cells in a room that gets too hot or too cold for the chemistry of your cells, and don’t store them near sources of heat like hot water heaters or furnaces. Another important tip for storing lithium batteries and cells is to not store them on things that could fall over or collapse. Finally, make sure to not store your batteries fully charged. The best voltage to store lithium batteries and cells at is around 60 to 70 percent of their maximum charge voltage. Doing this final step will ensure that your batteries don’t experience damage from the volatile nature of the chemistry inside the cell.

If you follow these things and practice some general common sense, then you won't have any problems and your batteries being stored will work as well as you expect them to. We hope this article helped you learn how to safely store lithium batteries and cells. Thanks for reading!