10Pcs/Set 3.7V 1200mah Rechargeable 18650 Li-ion Battery LED Flashlight Batteries High Protective

When I write a review on electronic items from China, I always take into consideration the fact that too many people expect to get the same performance from a one dollar item as a similar ten dollar item. Sorry, but it just doesn't work that way in the real world. I've seen a lot of "less than stellar" reviews on these particular batteries, but I have to discount all of those now because - for me, these batteries work just fine. I tested them with a volt-meter as soon as they arrived and they all came fully charged out of the box. My primary use for the 18650 batteries is high-lumen flashlights, and these work just fine. Will one of these last as long before needing a recharge as a Nitecore battery that costs ten or more dollars? No, it won't. Will it recharge as many times as a much more expensive brand-name battery? I doubt it. But in the meantime, I've got four of these in flashlights and I've re-charged them several times without any issues. It seems the 18650 batteries are becoming more and more expensive, with some costing more than ten dollars each. I don't know what's causing the steady price increase, but I'll just keep paying for the dollar or dollar-and-a-half versions as long as they work. Just remember, you get what you pay for (in most cases). This particular brand has not failed on me yet. If I get a few failures, I'll switch to another brand of the less expensive batteries. But for now, these are just fine.

Im dissappointed that AMAZON allows these type of products.......I don't know why they cannot give a preliminary inspection., before they are offered to the consumer.......And what happens is that you only find this out after the warranty expires...These batteries might last a week or a month......Then they lose their charge and become uselessI threw all 10 of them away...BTW, they are NOT standard size 18650........The listing mentions this in a secretive way, but I did not realize that at the time.....They did not fit into my vaporizer correctly.......It was a very slight size difference....... I really don't know what appliances these size batteriesare made for.......

Average capacity is 1200 mAh, not 4000. Initial test of two with simple resistor and voltmeter suggested capacity about 1000 mAh, so I bought a battery tester (Zanflare C4, works well) and checked all 10. Average capacity is 1215 mAh (standard deviation 70.2).Two Samsung 18605's advertized as 2500 mAh were 2706 and 2724 with the same test.The basic chemistry of Li-ion batteries makes it difficult to pack more than about 2800 mAh in a 18650 package. Any 18650 battery advertised above about 3000 mAh is either intentionally misleading (let's call it a downright lie), or should be extremely expensive to recover the technology development, or far in the future!

I tested these against a batter rated at 2400mah. The 2400mah battery lasted a little longer in the same flashlight. No way these are 4000mah. That said these are cheap enough that it doesn't matter all that much. Plus, it doesn't hurt to have 10 of them for backup.I really wish all battery manufactures were forced test at an independent lab. Every manufacturer seems to set their own "standards". After all, current * time is really all it takes to come up with an accurate rating, even though it may vary a little based on the current.

I received ultrafire batteries, I think they're claimed to be 4000mah on the wrapper. After a few charge/discharge cycles I tested them with my xtar vc4 as well as a USB port tester for total capacity in the add-your-own-batteries power banks I'm using them in. They average just over 1200mah, usually slightly higher with a max of just over 1400mah on a few batteries.I would buy more of these, but some of the power banks I have need flat top 18650s.

You get what you pay for. Using an oscope on a time/voltage plot with similar load, these always measured out about 7-800mah. The reputable brand batts claiming 3ah gave me right at 3ah. I thought I was clever by obtaining 10x 4ah batteries for like $10. Sure enough, they all lasted about 10 mins in a flashlight that gave me 2 hrs with an Olight 3500mah battery.

1200 mah NOT 4000 I mean I knew these wouldn't be 4000mah for the low price but geez!!! Put on charger ran discharge and recharge all batteries came back just under 1200 mah!! Anyway gonna return.

These batteries said in the description that they were 3000mah but the batteries I received are labeled 4000mah. That would be good if they where but after testing them they appear to be around 800mah and they drop charge after around 35 percent. I wouldnt buy these for anything that needs a decent size current draw.