Rechargeable lithium ion batteries are becoming common in electronic equipment and camera trapping is no exception. I use the 18650. 26650 and NP-F batteries in many of the camera traps and products we manufacture at TRLcam. The capacity of the cell makes for smaller products with much longer battery life.


A few weeks ago I was looking for something on Amazon and stumbled upon this battery capacity tester. US$7.99 shipping included. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 It looked simple enough, maybe it will work. So, a few days later the UPS made his daily stop and delivered this piece of tech. The package included the board and a couple 7.5 Ohm 5 Watt resistors. This product can be used to test any type of battery and by changing the resistors you can vary the current draw on the battery. It might be interesting to test different brands of AA rechargeable batteries.





The 7.5 Ohm resistors are used to set the current draw of the battery under test. With a 18650 battery voltage of 3.7 Volts, one 7.5 Ohm resistor will put a 500mA load on the battery. Put the two resistors in parallel and it will draw 1 Amp and if you put the resistors in series a 250mA load will be applied to the battery.


After going through my bin of 18650 and 26650 batteries I came up with a few assorted brands and capacities of batteries.





So, I started testing. Here are a few of the results:


Panasonic NCR18650B - printed capacity 3000mAh - tested capacity 2909mAh
EBL BRC18650 - printed capacity 3000mAh - tested capacity 2289mAh
Tenergy 18650 - printed capacity 2600mAh - tested capacity 2208mAh
IMR 18650 - printed capacity 2500mAh - tested capacity 320mAh
LCYYO BRC18650 - printed capacity 3000mAh - tested capacity 1894mAh
Westinghouse INR18650F - printed capacity 3350mAh - tested capacity 2887mAh
LumiTact 18650 - printed capacity 2600mAh - tested capacity 1925mAh
Tenergy ICR18650 - printed capacity 2200mAh - tested capacity 2106mAh
UltraFire BRC18650 - printed capacity 4000mAh - tested capacity 1824mAh


EBL 26650 - printed capacity 5000mAh - tested capacity 5034mAh
Ultrafire 26650 - printed capacity 6000mAh - tested capacity 1745mAh


NP-F550 - printed capacity 2200mAh - tested capacity 1972mAh
NP-F750 - printed capacity 5000mAh - tested capacity 3948mAh
NP-F950 - printed capacity 7900mAh - tested capacity 5293mAh
Inside the NP-F batteries are 18650 cells. The F550 has two cells in series, the F750 has four cells and the F950 has six cells. All NP-F battery packs put out 7.4 Volts.


I had several of the UltraFire 18650 and 26650 batteries in the bin so I tested three of that model battery. They all were way below the manufacturers listed capacity.


It is very difficult to buy genuine batteries on the internet. One of my favorite 18650's has been the Panasonic NCR18650B manufactured in Japan. You can go to AliExpress and see many copies. You can even purchase heat shrink battery skins to make any 18650 into a Panasonic NCR18650. Buyer beware.