I have a LOT of experience in testing and using 18650 cells. It is a horrible place for the un-initiated to be. The market is so saturated with dangerous fakes and inferior, over-speced cells that finding a genuine cell is a vanishingly small probability. Hopefully the seller mentioned before pans out and sticks around. You can be pretty much assured that any no-name Chinese cell will be dangerous crap. Buy a 3000 mAh cell that is really 500 mAh and charge it at the 3000 mAh 1C rate and KERBLOOIE! If you want to buy decent cells from a reputable maker (Samsung, Sony, Panasonic, etc) you have to be certified that you know how to properly build with and use them... and also the minimum order quantity can be over 100,000 pieces. Shop around and you can find sellers of 18650 shrink wrap sleeves for all the major/reputable cells. I have yet to test a Chinese cell that comes even close to its advertised specs. Also probably 90+% of what is offered as genuine name brand cells are fakes. Your best bet for finding a decent cell is to get them from GENUINE laptop packs. That is easier said than done... counterfeit packs are the norm. Also, most newer laptops use packs with pouch cells. 18650's are on the way out for modern machines.

On Sun, Jan 22, 2017 at 9:36 AM, Mark Sims <holrum@hotmail.com> wrote: > I have a LOT of experience in testing and using 18650 cells. It is a > horrible place for the un-initiated to be. The market is so saturated with > dangerous fakes and inferior, over-speced cells that finding a genuine cell > is a vanishingly small probability. Hopefully the seller mentioned before > pans out and sticks around. I agree, many fakes. But you CAN buy through reputable distributes like Amazon.com for maybe $16 per cell. When I buy a battery packs the cells are already shrink wrapped and who knows what is really inside, so I test the pack. I charge it up and then discharge it through a dummy load and track the power over time (actually my programable charger can do this for me) then I recharge it ti to "stage age voltage" and check that the self-discharge rate is reasonable. I've not had a problem with hobby type drone batteries and if I did I'd be covered by even a 30 day warranty or failing that by PayPall's chargeback policy. I'd 100% recommend that anyone who buys a lithium battery place it inside a fire proof enclosure then run it through a few charge/discharge cycles and very the seller's specifications. If you are not set up to do this kind of acceptance testing don't buy lithium. I can say first hand that once the lion battery fails, boiling electrolyte and white smoke will continue to come out of the battery no batter what you do, just take it outdoors and set it on the concrete and let it finish, dropping the assembly in a bucket of water will not help, they will generate a few hundred watts of heat until they run out of energy. One started it is a positive feedback loop. But not dangerous if you thought ahead to place the thing inside some metal container. Just carry the smoking mess outdoors and leave it there for a while. (I tried salvaging lithium cells for Milwaukee power tools with only about 50% success rate) -- Chris Albertson Redondo Beach, California