Original article: https://www.thunderheartreviews.com/202 ... rison.html
Samsung has a good lineup of 21700 Li-ion batteries and when i tested INR21700-50G i thought it would be interesting to test INR21700-48G cell too because the new batch of 48Gs came in green heat shrink tube (the version i tested before was gray). Then i added 50E results to comparison as they are very close in capacity and max discharge rate.
The batteries were bought from Queen Battery which is my reliable supplier of genuine cells 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.
50G and 48G cells were tested using my battery holder v.4.0. A detailed video about it is available on my channel.
I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle the battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hr pause. The environment temperature was 25±2°C. To be sure in results i've done each test minimum twice (usually 3-7 times).
Samsung 50G comes without any heat shrink tube on it and all the markings are printed on the cell barrel. The printing is not resistant to ethanol-based degreasers and is washed away easily, so if you're going to put a tube on 50G be careful while degreasing the cell surface. The cell is marked as:
There is also a 2D matrix code and 2 other markings:
Samsung 50G has the following specs according to its official datasheet:
Minimum capacity: 4850mAh
Nominal voltage: 3.63V
Standard charge current: 1.6A (0.33C)
Charge cut-off current: 121mA (0.025C)
Max. charge current: 4.85A (1C)
Charge end voltage: 4.2V
Max. discharge current: 9.7A (2C)
Discharge cut-off voltage: 2.5V
Max pulse discharge: 14.55A (3C)
AC impedance at 1kHz: 14±5mΩ
Max weight: 69.5g
Using 1.6A/0.33C charge current with 242.5mA/0.05C cut-off and 4.85A/1C discharge with 2.5V cut-off after 1000 cycles the capacity should be ≥3880mAh (80% of std capacity).
DC IR at 4.85A in fully charged condition was 20±1mΩ (measured using EB Tester Software's Resistance test feature).
Measured weight (without heat shrink tube): 68.02g
Samsung INR21700-50G battery's discharge capacity test results:
The real capacity doesn't reach 5000mAh but it's above 4750mAh even under 10A load. Curves look good.
Samsung INR21700-48G (green)
This time 48G cells came in green heat shrink tube. The previous version was gray. I don't have any information if there are any changes in chemistry but if you know something please share in comments.
The cell is marked as:
There are also two 2D matrix codes and a marking on the barrel, under the tube:
Samsung 48G has the following specs according to its official datasheet:
Typical energy: 17.4Wh
Minimum energy: 17.04Wh
Typical capacity: 4800mAh
Minimum capacity: 4700mAh
Nominal voltage: 3.6V
Standard charge current: 1.44A (0.3C)
Charge cut-off current: 96mA (0.02C)
Max. charge current: 4.8A (1C)
Charge end voltage: 4.2V
Max. discharge current: 9.6A (2C)
Discharge cut-off voltage: 2.5V
Pulse discharge (at 23°C ambient temp)
35A for 10 seconds
25A for 30 seconds
18A for 60 seconds
AC impedance at 1kHz: ≤35mΩ
Max weight: 69g
At 23°C using 1.44A/0.3C charge current with 240mA/0.05C cut-off and 4.8A/1C discharge with 2.5V cut-off after 500 cycles the capacity should be ≥3525mAh (75% of minimum std capacity).
DC IR at 4.8A in fully charged condition was 17±0.7mΩ (measured using EB Tester Software's Resistance test feature).
Measured weight (without heat shrink tube): 67.4g
Samsung INR21700-48G battery's discharge capacity test results:
At 0.2C discharge the capacity is in the middle from minimum to typical specified by Samsung. The capacity remains >4600mAh all the way up to 10A. Curves don't have any sudden drops.
Samsung 50G vs 48G (green) vs 50E
The results of 50E i took from my tests published before. Keep in mind that it was tested using previous version of my battery holder and its standard charging current is noticeably higher than 50G's and 48G's - 2.45A.
Comparison at 2A discharge current:
50E's capacity is a bit higher than 50G's but the energy is almost the same. 48G takes 3rd place.
Comparison at 5A discharge current:
The capacity of 50E is still a bit higher than 50G's but the curves show that its voltage is always lower all the way from start to the end and the energy is where the truth is hidden - 50G has more energy. 48G is again the 3rd.
Comparison at 8A discharge current:
Here is where the 50G takes the leadership. 50E is closer to 48G - the difference in energy is only 0.15Wh.
Comparison at 10A discharge current:
50G keeps the 1st place while 50E becomes even closer to 48G in capacity. The difference in energy is still the same - 0.15Wh.
Cycle life comparison:
48G is the clear outsider while two other cells can both take th first place. On one hand 50G should have 3880mAh after 1000 cycles (!!!) which sounds very impressive, but on the other hand 50E should have 3802mAh after 500 cycles each time being charged at 1.5 times higher current than 50G. I can't name the winner so i leave this up to you.
Here is the video version of this review:
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