Short review: DO NOT buy the Nitecore NL1835R 18650 battery. The cell per se seems acceptable but is completely marred by an extremely low quality and faulty protective internal circuit (IC) i. e. the circuitry that sits on top of the cell where you plug your charging cable.
Long review: I rarely make reviews for products but when I am forced to do so, it means that the product is really that bad.
I was in the market looking for a battery that had built-in USB charging capability and when I found the Nitecore NL1835R 18650, I knew I had to buy it seeing as for the most part, my experience with Nitecore flashlights have generally been pleasant. In my mind, I was confident enough that their batteries would deliver the same quality (I was obviously set up for disappointment).
I received my first order of the NL1835R last April 3. I used it for around 3 days and was having no problems. At that point I ordered another one because at that point my experience was quite pleasant. On the fourth day (April 7) while my second NL1835R was in transit, I noticed that the battery which was in my Nitecore HC30 at the time felt really hot (and mind you, it was not in use for literally hours). I took it out immediately and noticed that the indicator lights on the IC were going out of whack; flashing, then turning on steadily, then finally turning off after a few minutes. The IC wouldn’t charge after that and the button top would feel extremely hot even when not in use. I made sure my HC30 wasn’t broken so I used other batteries, which went well. Temperatures obtained using an infrared thermometer revealed it was overheating and checking the battery with a voltmeter revealed that it was gradually discharging probably as a consequence of the aformentioned. At this point I thought the IC must’ve failed so I sent a return request to Tactical Asia. The whole return process took longer than I expected. Sent the request April 8 and received the product April 21. But I have no problems with TA’s service in general as I have been buying products from them for a few years already.
The second battery meanwhile, which I received on the same day (April 7), had a good week or so of use then, boom. The same catastrophic IC failure happened (April 15, I think). I didn’t bother sending that for return as it was already past the 10-day policy of TA and not to mention I still was yet to receive the first one at that time. In fact, later on during that day, sparks were noticed coming from the IC as I tried to use it again. This is the first time I’ve seen this and so I immediately decided to dispose of it thinking that safety would have been a far more important priority at that point.
And now comes April 21; I received the brand new NL1835R from TA (3rd one now in case you lost track) after the first one failed. I seriously hoped it would be fine this time but… I used it again for a measly 2 days (it is now April 23) and that’s when the IC broke again with the indicator steadily glowing red even when not charging. At this point, I totally lost hope with the product and didn’t even decide to return the returned item (how ironic).
To end: Nitecore flashlights are great, and I cannot speak for the other models of their 18650s but absolutely DO NOT buy the Nitecore NL1835R model of 18650. It happened 3 times so I refuse to believe it as a product of coincidence. The internal circuit is garbage and is probably something, I suspect, that is cheaply made in China (battery components should be made in Japan as standard to be honest). It was a waste of my money especially since I paid 2,400 Pesos for two of these batteries and this makes me extremely frustrated. All it is now is a potentially hazardous paper weight. If I am to be completely honest, TA should probably drop this product from their inventory. You’re better off buying say, Keeppower 18650s (which I discovered shortly after the third one failed) whose cell and internal circuit are both made in Japan.