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Samsung 26J (26JM) 2600mAh low price cell's capacity test

Posted: Jun 22 2019 2:33am
by thunderheart
Samsung ICR18650-26J is a 2600mAh Li-ion cell of 18650 size which supports continuous discharge at up to 5.2A.

The battery was bought from my reliable supplier (Queen Battery) and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A.

I've used version 3.0 of my battery holder based on 0.5mm thick pure copper terminals

I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle each battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hrs pause. The environment temperature was 23.0-24.5°C. To be sure in results i've done each test minimum twice (usually 3-4 times).

Samsung ICR18650-26J

The cell is marked as ICR18650-26J M SAMSUNG SDIEM THR2 which means that the production date is 02 Apr 2017.

The main specs from Samsung 26J datasheet:
Nominal capacity: 2600mAh
Minimum capacity: 2550mAh
Nominal voltage: 3.63V
Standard charge current: 1.3A (0.5C)
Maximum charge current: 2.6A (1C)
Charge cut-off current: 0.13A (0.05C)
Charge end voltage: 4.20V
Max. continuous discharge current: 5.2A (2C)
Discharge cut-off voltage: 2.75V
AC impedance at 1KHz: ≤100mΩ
Max weight: 45g

Cycle life:
After 300 cycles using 1.3A charge / 1.3A discharge the capacity measured at 0.2C discharge should be ≥1785mAh (70% of initial minimum capacity).

DC IR at 2.6A in fully charged condition was 42.3±2.7mΩ (measured using EB Tester Software's Resistance test feature).

Measured dimensions: 18.3mm (diameter) × 65.0mm (length).

Measured weight: 43.87g.

Capacity test results:
At 0.2C/0.52A the capacity was a very little bit higher than 2600mAh declared. At 2A and 5A discharge it was around 2450mAh. The curves look excellent.
Samsung limits the charge cut-off current by 0.05C instead of more common 0,02C and the discharge cut-off voltage by 2.75V instead of 2.5V. With 0.02C and 2.5V the results would be better but i think Samsung is worried about cycle life of this cell - 70% of initial capacity after 300 cycles 0.5C charge / 0.5C discharge doesn't make me cry wow. Whatever, real-world cycle life could differ.
Samsung 26J is a good low-drain medium capacity 18650 cell without any special features. The price (somewhere around/below $2) makes it an excellent choice for large battery packs.

Here is the video version of this review:

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