Low drain endurance tests for elite brand 3100 mAh 18650 batteries.

As shown in the graph below, I measured the voltage drop in several top-brand 18650 batteries of 3100 mAh capacity. The brands tested were AW, Panasonic Industrial, Redilast, and Callies Kustoms. (I also tested an Ultrafire 3000 mAh battery that had an unusually high internal resistance, just because I was curious about it. It shouldn't be regarded as typical for Ultrafire brand batteries.)

The device used to drain the batteries was a Romisen RC-E4 flashlight with the emitter upgraded with a five-mode XML T6 LED drop-in bulb. The modes were bright, medium, dim, rapid blink, and SOS blink. The tests were done with the LED set on the dim mode, which starts out at about 60 lumens or so.

Prior to testing, each battery was charged until the voltage was in the range of 4.20V to 4.24V, as shown in the graph. Then it was put into the flashlight, which was then turn on and quickly to the dim mode. The same flashlight was used for all of the tests.

The AW 3100 and the Panasonic Industrial 3100 tied for third place, both of them doing the least well of the four batteries tested (excluding the Ultrafire, which basically is irrelevant to the comparison). The Redilast did significantly better, with a 5% longer elapsed time from ~4.2V to 3.0V. The Callie's Kustoms battery did the best overall, showing a 8.3% longer elapsed time (over the same voltage drop) versus the AW, and a 3.4% longer elapsed time versus the Redilast.

Only one battery of each brand was tested, so your results might vary if you repeat this experiment.

Nice test!

The panny 3100 doing the "worst" in the test sort of makes sense, as it has the lowest resistance of all the cells in the bunch. (having no protection IC - the AW, CK, and Redilast all use the same panny 3100).
I know that the iirc the callie has more resistance (from the protection IC) than the redilast, so the test data sort of matches up, but the AW cell being remarkably close to the panny 3100 doesn't make much sense.

I grossly estimate the vf of the emitter to be ~2.7V, not sure what the driver overhead is, though. From the data the circuit is probably a simple buck and output might not be the same with all the cells, I'm quite confused with the results of the ultrafire cell, though. :duh2:


Craig

The Ultrafire cell is a defective cell with abnormally high internal resistance. The voltage stays higher than normal, but the current is less, so the flashlight LED doesn't get any brighter (P=iV). If I were to put the flashlight on the high setting, the Ultrafire's restricted current would allow about six hours of continuous operation, as compared with 4 hours for the AW 3100 and maybe a little longer for the Redilast/CK. The actual capacity of the Ultrafire is said to be 3000 mAh and might be less.