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Are Lithium-Ion Cells You Buy Online Always Legit?

Posted by Vidyu Challa on May 31, 2018 11:45:00 AM

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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.

 Figure 1: Fake battery with mis-spelled words.

Figure 1: Fake battery with mis-spelled words.

CT scans of the suspect cells in Figure 2, show a much shorter jellyroll on the suspect cell compared to the known good, and that means less active material. This would translate into a lower cell capacity and discharge rate capability. Deconstruction of the suspect cell also showed heavily delaminated electrodes that demonstrate poor coating adhesion and low cell quality. No protection circuit was found in or on the battery as was claimed. One on-line forum reports opening up an 18650 lithium-ion cell of this brand name and finding a smaller pouch cell on the inside.

Figure 2: A) Fraudulent battery that has approximately 20% shorter jellyroll compared to B) Genuine battery

Figure 2: A) Fraudulent battery that has approximately 20% shorter jellyroll compared to B) Genuine battery

Battery Safety is a system level function

Lithium ion batteries have a narrow range of voltage and temperature where they operate safely as I discuss in a previous blog post.  It is the job of the battery protection system to make sure the battery stays within this operating window.  Battery protection systems however do not adequately protect against an internal short circuit, which are often a result of poor manufacturing quality.

Since lithium-ion battery safety is a function of cell manufacturing quality, protection adequacy, application integration, and user behavior, safety can be compromised by sourcing lithium-ion batteries online. This is of particular importance for high rate E-cig applications, since the manufacturing quality, specific lithium-ion battery chemistry and protection circuit adequacy are often unknown.

So, my recommendations for what I hope is the small minority that sources Li ion cells online:

  1. Do not buy batteries online unless you really trust the source
  2. Look for misprinted labels or typos on the labels and avoid these

 


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Webinar:

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