Well this sucks. Got the batteries today and one of them is dead. D E A D dead! DMM reads 0.0 volts. The other three read about 3.7. So, 25% failure rate. Not good. I contacted the seller. Let's see what he says.
On the whole, no, it's not a great sign. You would hope that if all the cells were from the same batch, were given the same storage charge at the time, and had the same self discharge rate etc. that they would all come with the same voltage. But then, who is to say that they did come from the same batch?
While the question remains as to why it has discharged, with a bit of luck, the zero voltage is just down to the battery's protection circuit having tripped, and there is no permanent damage to the cell. If you place the battery in to a charger, that should reset the circuit.
Sorry to hear that. Like Stephen said , hopefully you can reset the PCB. Keep us updated.
It got me thinking, why would it be dead? bum cell? used cells? I checked all four of mine and i did notice on two there is minor scuffs. These two cells I have not used and are still in the wrapper. One of them also has a tiny dent 
, so are they used (recycled) or just mishandled?? I will contact the seller ASAP
Used cells? Not likely. Mishandled possible. Were they packaged well when mailed?
For $3.75ea my guess is their junk. Do you have any way to test their capacity?
"Used cells? Not likely. Mishandled possible"
Why would they not be used cells? This is very very common with 18650 batteries in this price range. https://budgetlightforum.com/t/-/2359 I seems to me someone on CPF was complaining about some Tenergy 18650's coming in around 1400mah, indicating recycled batteries.
If you want to say they are fakes that is possible. But not likely. Have you looked at this ebay sellers batteries? He is selling many different Tenergy batteries. Too much trouble to fake several types for the small quanities he is selling. Large buy out of old stock? Possible. I have ordered some 18650s and tabbed AA NiMH. I will test them and give an honest report. Tenergy makes some of the BEST D cell NiMH when tested have exceeded 10000ma rating. Tenergy does make a good battery and are known for quality. They rate with Maha, Titanium and several other premium makers. Tenergys are not SUCKFIREs. I do have the ability to test capacity. I don't sell batteries. Do you? Yes! Let your batteries shine on thier own merit. Talking trash isn't good marketing. All you have is here say "Some guy says they are junk... All 3.75 batteries are junk" Buy some and test them. Put your money where your mouth is and give results not rumor or speculation.
Yes they were packaged well. Double bubble wrapped, batteries were also wrapped in plastic.
I have no way to test their capacity , but so far they are performing well in my TF TR 3t6 2x 18650 and also in my SF L2T & L2P. I don't believe they are used or fake cells, they might have been mishandled during storage. I know the price is to good to be true because they are $9 per cell anywhere else.
When will you test these tenergy's? I'm very curious what the outcome will be.
I will test them ASAP. I am off to hunt as bow season starts this morning. Had them sent to work Should be early next week.
Great can't wait ! Have fun ! I always wanted to do some hunting.
I ordered 4 of these. They all were 3.7V and look new.
I charged one and tested it in a flashlight. It drew 2.7A
In the same light a new Xtar 2600 drew 2.8A
OP: If you have not tried to reset the "dead" one in a charger....you should.
Those are some good numbers, I tested it in my manafont 3mode xml and it drew 3.3A quickly dropping and maintained at 2.98A after 2 min.
How long do I need to leave it in the charger to reset it? I put it in the charger for about an hour and still nothing. The charger doesn't look like it's charging, the battery isn't getting warm at all, and when I check it again with the DMM is still reads 0.0.
I did contact the seller and he replied that he would send out a replacement on Monday.
Indeed a DOA. Defected battery. +1 for the seller.
I don't suppose putting in in a multi-cell light with another battery might jumpstart it or reset it or whatever? Or am I just asking for an explosion by doing that?
Probably best not to put it in a light with another cell.
If it was going to reset, it would happen as soon as you placed it in the charger. It's possible that your charger may not have the power to reset the circuit, hard to say, but it should happen straight away.
I believe that the seller's stock is from liquidation sales, hence the low pricing. They are getting them at rock bottom prices from businesses that have closed for whatever reason, and selling them on cheaply.
It should have reset in the charger. If you dare, you can put it in a light with another hot cell and then just hit the on switch for a quick "bump" then OFF. It only takes a second for it to work....or not.
I would just trash it.
Well crap...now I have another problem with them. None of them work in a multi-cell light. From what I can tell by looking at the batteries, the positive and negative ends are completely flat so when I use them in a multi cell light, the positive end of the last battery doesn't touch the negative end of the front battery.
Is there something I can safely put between the batteries to fix this? This is really annoying. I got them specifically to use in a two-cell light. If I can't use them for that, they are pretty much useless to me.