Lumafield has released the results of a new study of lithium-ion batteries that “reveals an enormous gap in quality between brand-name batteries and low-cost cells” that are readily available through online stores including Amazon and Temu. The company used its computed tomography (CT) scanners, capable of peering inside objects in 3D using X-rays, to analyze over 1,000 lithium-ion batteries. It found dangerous manufacturing defects in low-cost and counterfeit batteries that could potentially lead to fires and explosions.
The study tested 18650 lithium-ion battery cells, which are used in various products including electric toothbrushes, power tools, e-bikes, power banks, and even electric cars. The batteries were purchased from ten different brands: three OEMs, including Samsung and Panasonic, sourced from “highly reviewed, specialized suppliers,” three vendors selling rewraps (typically OEM batteries with their plastic outer wrapping replaced) sourced from “specialized battery sites” or the brand’s own web stores, and four companies selling low-cost or counterfeit batteries sourced from “large, general online retailers such as Temu.”
Lumafield scanned 1,054 batteries – around 100 from each brand – and found 33 of them had a serious manufacturing defect known as negative anode overhang. The defect “significantly increases the risk of internal short-circuiting and battery fires” and can reduce the overall life of the battery,” according to Lumafield. All 33 of the batteries with the defects came from the 424 sold by low-cost brands or brands selling counterfeits. One of the counterfeits was identified by its pink wrapper designed to match the one Samsung uses on its 30Q cells. Other low-cost brands claimed capacities of 9,900 mAh while brand-name 18650 batteries have capacities in the range of 3,000-3,450 mAh. Not only were the counterfeits’ specs overinflated, but in real-world testing Lumafield found their capacities were less than 1,300 mAh.
When taking only low-cost/counterfeit batteries into consideration, there’s nearly an 8 percent chance they could have the dangerous negative anode overhang defect, based on Lumafield’s findings. For two of the counterfeit brands that were reporting impossible specs, the percentage of tested batteries from those brands that were found to have the defect were even higher – upwards of 12 and 15 percent. None of the name brand OEM batteries were found to have any problems, and while there was some deviation in anode overhang for rewrap batteries, the deviations were seven times worse for the low-end cells.
When looking at other indicators of build quality, all of the batteries from the low-cost brands also had much worse edge alignment of their internal wound layers than those made by reputable OEMs, increasing the risk of short circuits and performance loss.
Defects like negative anode overhang and bad edge alignment don’t mean an affected battery is guaranteed to explode or catch fire, but they can increase the risk of those incidents occurring, particularly when combined with other factors such as being left in a hot car or an accidental drop causing additional damage.
The results of Lumafield’s study suggest that batteries from reputable OEMs like Samsung, Panasonic, and Murata are safer and more reliable. And while rewrap batteries fared well in Lumafield’s test, their replaced wrapping makes it difficult to know exactly where they’ve been sourced which increases risks due to a potential lack of quality control in supply chain management.
Not everyone has access to an X-ray CT machine to test the quality of the cells in every battery-powered device they purchase, but the study is a reminder that purchasing devices from reputable brands can increase the chances that their batteries are free of dangerous manufacturing defects. Trying to save money with less-known brands could end up costing you a lot more in the long run.
