Are my 18650 batteries fakes?
I just happened to read and watch this today : https://batterybro.com/blogs/18650-wholesale-battery-reviews/104619270-can-you-identify-the-fake-lg-hg2-18650-battery
Selling older models in new wrapping certainly gets around the weight issue!!
I have just received six Samsung 18650s for my remote sensors, from an eBay dealer here in Germany, when I checked the price against Conrad Electronic, I found the ones I had bought to be half the high street retail price, so I started wondering if they were genuine or not, maybe the online seller had also been hoodwinked, who knows.Anyway, 5 minutes of research on the internet put my mind at ease. A simple test to check whether they are fake or not is to weigh them. Genuine 18650s should weigh 42g or more, whereas if they weigh less than 40g they are definitely fake.
Weighing is a good quick check. However, in some cases they are adding sand to the case with that possibility in mind. The best way, I think, is to fully charge one to ~4.2VDC and then discharge it through a suitable load down to either half way at 3.7VDC or down to 0% at 3.3VDC, and then measure the mA of current it takes to bring it back to full charge. Then you'll know, comparing the result to the rated mAh for the cell. Many of the ultra low cost cells I've seen are a fraction of their rated capacity.