behind battery report
Behind the Battery Report Today, we released Lumafield’s Battery Quality Report, an investigation into the dangers lurking within the lithium-ion battery supply chain. For this study, I CT-scanned 1,054 cylindrical 18650 cells from ten different brands, ranging from reputable, well-known battery manufacturers to ultra-discount cells from Temu and many sources in between. As battery users, we all instinctively expect alternative-brand cells to be of lesser quality, but it’s easy to understate how bad they can actually be, especially when a cheaper looking one promises similar or better specifications, and the name brands seem prohibitively expensive. However, our CT scan revealed much bigger quality flaws than I could have imagined, and once we learned how dangerous a bad battery can be, the story curiously turned into something really worrying. Delving deeper into questions of battery quality As a technical product marketing manager at Lumafield, I design experiments to test and show how engineers can leverage CT to solve real problems. I’m constantly looking for areas to double-click, and as a gadget-lover, battery is often on my mind. A few months ago, I wrote a blog post about the Anker A1263 power bank recall, and it achieved a surprising level of virality considering the relatively non-glamorous product involved. But perhaps it is the practical prevalence of batteries in all of our daily lives that has generated so much interest in this piece. In that article, I scanned five power banks: enough to make some solid observations, but a small sample before the realities of production scale. I wanted the insights that could come with a larger dataset, and 18650 cells seemed like the obvious choice. 18650 are standardized battery cells, as their name suggests they have a diameter of 18 mm and a length of 65 mm. These cells are absolutely everywhere. More than five billion are produced each year, and they can be found in everything from electric toothbrushes and cordless drills to some electric vehicles. For example, every Anker power bank I scanned had 3 18650s, and my colleague’s e-bike battery had 39. Although most 18650s are assembled in packs of several cells and deeply integrated into devices, there are some applications where the cells are user-replaceable, such as vapes or flashlights, making them relatively easy to purchase. Study Methodology I ordered at least 100 cells from each of the 10 brands, ending up with a total of 1,054 cells, receiving the minimum purchase increase and free extras. Every cell was scanned. The three sets came from well-known OEMs—Murata, Samsung, and Panasonic—which were obtained from reputable online stores specializing in 18650 batteries. The three sets came from rewrap brands eFest, Backtail, and Trustfire, with eFest and Backtail coming from the reputable 18650 online storefront, and the Trustfire sale coming from their brand website. The last four were more questionable. I chose three brands because of low cost: TreasureCase and Maxion came from Temu, Benquia from Amazon. The SOOCOOL cells were not cheap, but advertised as “authentic” Samsung 30Q cells on Amazon, their casings closely but not completely mimicked the aesthetic of genuine Samsung cells. A counterfeit SOOCOOL “Authentic 30QP” next to an OEM Samsung 30Q cell. Table of cells scanned for the experiment. Each battery was labeled for traceability upon arrival, then scanned upon receipt. We performed scans on a Lumafield industrial CT system with a 130 kV microfocus source. Using ultra-fast CT, we scanned each cell in under a minute, then processed the data with our battery analysis module, which automatically finds electrode edges and extracts study metrics in bulk. Lumafield has two industrial CT product lines: Neptune, a compact and easy-to-install solution that is ideal for R&D offices and laboratories, and Triton, optimized for high-volume environments. We built the workflow to reflect production realities, as annual battery production is very large and speed dictates practical value. In production, Triton can be combined with ultra-fast CT to scan cylindrical cells in less than five seconds, enabling more than 720 cells per hour and enabling large-scale battery inspection. To support what we saw on the CT scan, I added some supplemental tests. I measured the capacitance on one sample from each set. Marketing claims have shown some cell listings to have a capacity of up to 9,900 mAh, a number far greater than this format can provide, and measurements have confirmed the mismatch. We also ran longer scans on some cells to resolve more subtle details and validate the automated measurements. Defining battery quality characteristics The analysis focuses on what controls safety. I preferred three parameters for anode overhang and two parameters for alignment. Median anode overhang per cell gave us a baseline for each brand. I used the median instead of the mean because some extreme outliers would have distorted the average. I also compared the maximum and minimum anode overhang values for each cell. Insufficient overhang increases the possibility of lithium plating during charge, which accelerates aging and increases the likelihood of internal shorts. Alternatively, excessive anode length may reach the CAN and create a separate short path. For alignment, we calculated the delta between the highest and lowest positions of both the cathode and anode. Cylindrical cells become wound, and telomeres introduced during winding can cause shorts and other faults. Large deltas point to weak process controls and higher risk elsewhere in the line. Comparison of good and bad anode overhang. Side-by-side of ideal and questionable edge alignment. Conclusion: More variation than expected The results were generally consistent with our expectations, but the degree of variation was surprising. The OEM cells showed tight control, with anode overhang centered close to the 0.50 mm industry average and slight telescoping. The rewraps generally matched the OEM intermediates quite closely, although their spread was wider, and notably the minimal overhang extended downwards to the tail. Trustfire stood out from eFest and Wapsell with fairly poor distribution, a reminder that rewraps are blind boxes that carry real risks. Unless you scan and measure what you buy, you can’t be sure what’s really hiding down the sleeve. The low cost and gimmicky group was in a league of its own. Distributions in each metric were wide, and every brand in this tier produced at least one unit with negative anode overhang. The worst results came from Temu Brands. We found fourteen treasurecases and fifteen maxion cells with cathode overhangs. In the entire low-cost group, cathode overhang was present in thirty-three of 424 cells, which suggests that one in thirteen such cells may have a geometry that accelerates aging and increases the high probability of internal shorting. The standard deviation is approximately seven times larger than OEM, indicating much weaker process controls and, by extension, a greater likelihood of other hidden defects. Implications and Recommendations These findings have implications for every stakeholder interacting with batteries, from battery manufacturers and device integrators to end users. Original battery manufacturers prioritize quality, and study results reflect their strict specifications and strong performance. The risk for these companies sits downstream, with scrap potentially making its way to the rewrap market, or OEM cells being “recycled” and resold when end-of-life devices are dismantled. Scraping processes and vetting of channel partners, as well as improved traceability features, can protect these brands from being tarnished by the actions of less honest players. Device integrators can reduce the risk of dangerous batteries by validating their supplies with incoming inspection, especially when purchasing through distributors or less established sources. Battery incidents can seriously damage the reputation of device integrators, making verification critical. Pack design is also essential to ensure battery safety, as building in sufficient distance and protection can limit potential failures to a single cell. Given gaps in supply chain and regulatory oversight, consumers must also proactively manage their personal battery risk exposure. It is important that users do not mix brands, capacities or ages in a shared device, that they protect cells from physical abuse and extreme temperatures, and that end-of-life batteries are properly recycled. Despite the popularity of “duplicates”, when it comes to batteries, the savings are not worth the risk. Consumers should also be familiar with the warning signs of battery incidents. Warmth, swelling or soft feeling during or after charging, hissing, strong chemical odor, discoloration, liquid residue, sudden drop in capacity, frequent shutdowns, or a charger that refuses to start all indicate internal damage. If you see any of these indicators, immediately discontinue use of the battery and dispose of it at an appropriate facility. Different Considerations Today’s volatile trade and tariff environment is making cell origination more complex than ever, and slipping gray-market alternatives into supply chains is becoming easier and more attractive. In such a disturbed ecosystem, CT becomes a practical tool for certainty. Our 754 non-OEM cells were mysterious until we scanned them, and while some matched OEM behavior, others were far from any proper specification. Most failures will never cause a fire, but even simple reliability failures can disrupt the functionality and experience of a product. The rare occurrence of battery fires is devastating, and this is why battery quality is fundamentally important. Negative anode overhang and large irregularities in edge alignment do not guarantee failure, but they tip the scale heavily in the wrong direction. Everyone who interacts with batteries, from cell manufacturers and device integrators to the people who use their products, must be mindful of the stewardship of these inherently dangerous devices. Lumafield Battery Quality Report reveals the magnitude of risk in an unregulated battery supply chain. Industrial CT inspection allowed us to explore the risky realities of the 18650 cells we ordered, turning some of those key quality indicators into measurable geometries. Ultimately, CT is a powerful tool that can make the invisible visible by bringing much-needed clarity to the unknowns of the battery supply chain. SEO Meta Description: A closer look at the battery quality report: methodology, surprising results, and what CT scanning revealed inside low-cost lithium-ion cells. A CT scan of 1,054 18650 batteries revealed major quality differences between OEM, rewrap, and low-cost cells, with defects concentrated in the cheapest brands. Negative anode overhang and poor alignment were the major risks, increasing the likelihood of internal shorts, accelerated aging and thermal events. The study highlights supply chain vulnerabilities and shows how CT can give manufacturers, integrators and consumers clearer information about battery safety.
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