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Why Do Lithium-Ion Batteries Swell?

Posted by Vidyu Challa on May 24, 2018 2:22:00 PM

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In recent years the practice of buying spare e-cigarette batteries online has started to increase, with some users scouting for higher amp-hour/power batteries in order to get a better vaping experience. This is particularly true for mechanical mod e-cigs, which are highly customizable and do not use protection circuitry. The battery protection circuit is what keeps a lithium-ion battery within its operating window, and prevents it from overheating, overcharge and other potentially dangerous situations.

Counterfeit, Rewrapped and Other Fraudulent Lithium Ion Batteries

Because lithium-ion batteries have been reported to cause thermal events and explosions in e-cigarette applications, mislabeled batteries are a major concern. (Tragically the first E-cig related death from a battery was reported this month).  Mislabeled batteries include fraudulent batteries, counterfeit batteries, and rewrapped batteries. Counterfeit batteries are those that are intentionally trying to masquerade as a battery from a reputable brand, while fraudulent batteries are those that make false representations of capacity and electrical performance. Rewrapped batteries are batteries which were made by one company and are sold by another company under a different brand name. While some rewrapped batteries are simply safe, lower-grade cells from major manufacturers sold as budget cells, others can be defective, or unsafe cells that are intended for recycling.

How Do You Spot Fraudulent Li Ion Batteries Online?

I recently came across fake cells on a major online retailer’s website while I was scouting for 18650 Lithium ion cells (and yes, I did pick the cheaper ones from available options). An inspection of markings on the cell case (Figure 1) revealed misspelled words, often a telltale sign of fraudulent, rewrapped or counterfeit batteries. These cells were also measurably lighter than typical 18650 cells. 18650 cells typically weigh at least 42 g, while the suspect fraudulent cells weighed 34 g, indicating less active material and lower capacity than an 18650 should have.

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Topics: Lithium Ion Battery, Battery Reliability, Battery Safety, Battery Failure