If you have a collection of flashlights, the temptation to buy higher capacity protected rechargeable Li-Ion batteries is quite strong. At times, the bundled cells aren’t the most capacious and might not give enough run-time to satisfy all needs, so getting another battery is a good idea. Or, perhaps, getting the biggest (legitimate) 18650 that I could find.
This proved to be another spur of the moment buy while strolling through Apliu Street in Hong Kong on my recent trip – this is known as a flea market for various electronics and features a lot of variety and decent prices. Unfortunately, for the unscrupulous, there are lots of fake and counterfeit items as well which might be hard to avoid at times.
I walked into a fairly decent looking hardware shop and found this Nitecore branded 18650 claiming 3500mAh. After looking up the product online and finding this was a genuine claim, I decided to ask the shopkeeper to let me cautiously examine the package. While never having handled a Nitecore battery package, I couldn’t tell for sure if it was real or fake, but decided to buy it anyway.
The battery cost HK$108, or about AU$19, which is fairly pricey for an 18650. However, it did claim a larger capacity than the Panasonic 3400mAh cells which were previously known to be the reigning capacity champion (although requiring extended charging/discharging voltage, if I recall correctly), while being protected for safety.
Generally speaking, I’ve had generally good things to say about Nitecore products, so I chose to buy the battery on the goodwill of the brand. The wrapping sports their familiar black-and-yellow scheme.
While the top cap was blank, at least the bottom cap had the branding stamped into it. That was a little reassuring. Of course, I had no way to know whether it was the real deal until I got home.
Testing (or Torturing …)
As soon as I got home, I shoved it into my HC60 and used USB to charge the battery up as I had no standalone charger. Using this method, I would be able to see the realistic capacity under use conditions – since I believe the HC60 charges to the “normal” 4.2V limit rather than an extended 4.35V or similar.
For load testing, I decided to run it with my BK Precision 8600 (yep, I love it) and a random 18650 battery holder clipped to a short 20cm 16AWG wire terminated in spade connectors to the electronic load. For comparison, I tested the already used bundled Nitecore 18650s I got with my MH10 and HC60.
The comparison tests were done at 1A, with a stress test done at 4A (as Nitecore’s protection claims to be able to handle it). Plotted versus time, it was clear that the 3500mAh cell was able to exceed the other cells in run-time and mostly maintain a higher voltage profile. The 2300mAh cell struggled a bit for voltage, whereas the 3400mAh cell didn’t quite reach as high a capacity. Under 4A loading, it achieved about 50 minutes of operation with a reduced voltage due to resistance within the protection PCB and test rig, but it did not cut out, and even though the cell was warm-ish, nothing bad happened.
Plotting it more conventionally, with capacity as the horizontal axis, we see that the 3500mAh cell was about to deliver 3484mAh at 1A and 3458mAh at 4A. That’s as close to the label rating as you’re likely going to get, and represents the cell as being the real deal. The voltage was a little lower at the higher current, so you wouldn’t extract as much energy, as expected.
The 2300mAh comparison cell registered 2268mAh, showing it was fairly honest, but the 3400mAh only registered 3166mAh, thus acting more like a 3200mAh cell. Maybe that cell requires extended voltage operation to reach the full rating, or that cell may have worn out somewhat from the fact that both cells were actively used since purchase.
The Nitecore NL1835 purchased from Hong Kong certainly seems to be the real deal and does achieve the claimed 3500mAh rating with a measured result of 3483mAh at 1A and 3458mAh at 4A. It sustained 4A discharge with no untoward effects, although was somewhat warm. Overall, despite its slightly high price, it does offer me exactly what I was looking for.