Lithium batteries are the workhorses that power much of the modern world. These ubiquitous devices do everything from keeping your laptops & smartphones running to powering EVs.
The demand for lithium batteries is enormous and growing exponentially. Trying to pin down the precise numbers manufactured each year is difficult. However, in the US alone, the market was worth $40.5 billion in 2020. This is expected to grow to $91.9 billion by 2030.
In such circumstances, the rise of a used-battery market is inevitable. But should you buy a second-hand lithium battery?
Lithium Batteries: How They Work
You should understand how lithium batteries work, as, ultimately, this can have a significant bearing on your decision. We won't go into too much detail, but it is valuable information to be aware of when considering buying a second-hand lithium battery.
Lithium Batteries: The Components and How They Work Together
A lithium-ion battery typically consists of three main components:
- Cathode: This is a metal oxide
- Anode: This is typically made of carbon
- Electrolyte: This is a lithium salt in an organic solvent
When you charge your device, lithium ions are released from the cathode and pass through the electrolyte to the anode. When the battery is discharging, the flow of ions reverses. This flow is what generates the electrical current that powers your device.
The Electrolyte Factor
One of the considerations when deciding whether to purchase a second-hand battery is its performance. Several factors can contribute to a degradation in battery performance. But the main culprit is the electrolyte.
Over time, the electrolyte reacts with the electrode materials, forming solid electrolyte interface (SEI) layers. These layers can impede the movement of lithium ions between the electrodes, reducing the battery's capacity and performance.
Additionally, tiny needle-like structures called dendrites can form and grow in the electrolyte. These can be potentially dangerous and cause batteries to short-circuit and overheat. In extreme instances, this can cause a battery to catch fire.
Containing and Controlling the Stored Energy
For their size, lithium batteries store a lot of energy. Along with their affordability, this factor is one of the main driving forces that has seen the battery become one of our principal energy storage mediums.
But energy, in any form, can be dangerous if it is not contained and controlled. This energy is a blessing when it comes to powering your car or laptop. But if you leave it to its own devices, the story can be different.
Even new batteries are not immune to a "loss of containment". One such example is the infamous Samsung Galaxy Note 7, which had a battery prone to exploding. Granted that this is an extreme case, but it does illustrate what happens when all that energy is not controlled.
As an analogy, it is useful to compare lithium batteries with gasoline. Gasoline is a perfectly safe energy storage medium if it is stored correctly (contained) and its energy release is controlled. The same rules apply to lithium batteries.
Most people would be sensible enough not to carry their gas around in a damaged or leaky gas tank. A damaged battery casing effectively mirrors this risk.
So, Is it a Good Idea to Buy a Second-Hand Lithium Battery?
The short answer is no. Buying a second-hand battery is always a risk. There is the performance degradation of the battery to consider, for starters. But perhaps the most compelling reason is safety.
The safety factor is so concerning that tightened legislation on selling second-hand batteries is inevitable. We can look at one product type as an example—many reports of e-bikes and e-scooters catching fire. A recent case of an e-bike lithium battery exploding and causing a fire in a Manhattan apartment block was followed by a raft of legislative proposals, including:
- Prohibit the sale of batteries that have not been tested and labeled by an authorized body.
- Prohibit the assembly and sale of refurbished or second-hand lithium-ion batteries.
- Employers using delivery workers would be required to distribute training material describing how to use, store, and charge electric transport devices safely.
It is more than probable that other national and local legislation will follow.
What If I Need to Buy a Second-Hand Battery?
So, buying a second-hand battery is not a clever idea. But what if you must? For instance, perhaps you have an older piece of equipment that takes a proprietary battery that is no longer manufactured.
There are some steps you can take to make sure that the second-hand battery you buy is primarily safe and has some useful performance left.
- Visual inspection: Remember the gasoline analogy? The battery must be in good physical condition to store that energy safely.
- Test the capacity: The easiest way to do this is with a Battery Capacity Tester. This will confirm how much charge the battery can hold.
- History: Try and find out about the battery's usage history. Ask about factors like the number of charge and discharge cycles. Additionally, the storage conditions are important. A battery exposed to extreme temperatures or abusive usage may be degraded or damaged.
- Certification: An uncertified battery should be avoided in any circumstances, but this is even more relevant when choosing a second-hand battery. Examine the battery and look for certifications and ratings from reputable organizations such as UL, FCC, and CE.
- Buy from a reputable source: Check the credentials of the seller. A reputable retailer will check the batteries for safety and capacity before they sell the battery. They may even offer a warranty on the product, although these are usually fairly limited in what they cover and how long it lasts.
- Compatibility: Make sure that the battery you are considering is compatible with your device and the charger. It can be dangerous to use incompatible chargers.
Ultimately though, buying a second-hand battery can be a hit-or-miss affair. The problem is that if you miss, the consequences can be more than just purchasing a dud bit of kit. It can be downright dangerous.
Take Care With Batteries
It might seem like we're giving lithium batteries a bad name, but nothing could be further from the truth. Lithium batteries are technological marvels that are transforming the way we power society. But densely packed energy in any form can always unexpectedly release itself with spectacular results. This is something that should be avoided for obvious reasons.
Second-hand batteries will always be more prone to reliability and performance issues. The best advice is to only opt for them when there are no other viable options.