Samsung INR18650-25R cycle test.
- Thread starter electricbike
- Start date
Ohbse
10 kW
We all know hitting the cells hard on discharge is going to have an impact on lifespan and it's definitely awesome to quantify the difference between several different discharge rates, however this testing is not that comparable to real world use. On my bike my load varies between 0.5c cruise and 3.5c peaks. Those peaks come at fairly random intervals and for varying, but usually short amounts of time. Pulse discharge testing cells consistently is a lot more complex but would be the ideal. This is not a criticism, just an observation.. loving the work you're doing.
One thing that I don't think has been quantified particularly well in other 18650 testing is the effects of fast charging independent of discharge rate. This could be tested by performing a 1c discharge for two cells, however vary the charge rate - perhaps 1.5a for the 'slow' charge' and the rated 4a maximum for fast. I appreciate these cycles will take quite substantially different times, however you probably don't need to do hundreds of cycles to establish trend data we can overlay on your long term testing. Unlike the discharge testing this is directly applicable to the real world scenario - you generally do charge at constant current!
One thing that I don't think has been quantified particularly well in other 18650 testing is the effects of fast charging independent of discharge rate. This could be tested by performing a 1c discharge for two cells, however vary the charge rate - perhaps 1.5a for the 'slow' charge' and the rated 4a maximum for fast. I appreciate these cycles will take quite substantially different times, however you probably don't need to do hundreds of cycles to establish trend data we can overlay on your long term testing. Unlike the discharge testing this is directly applicable to the real world scenario - you generally do charge at constant current!
electricbike
100 W
Uppdated 240 cycles.
electricbike
100 W
Uppdated 260 cycles.
electricbike
100 W
Uppdated 280 cycles.
parabellum
1 MW
How many cycles do you plan to run on this cell?electricbike said:
DrkAngel
1 GW
500 cycle series scheduled ... I asked previously.
parabellum
1 MW
Would be interesting to see 2000 cycles outcome, for those LiFePO here LiFePO there guys.DrkAngel said:
I am getting sick of this 2000 cycles argument already.
DrkAngel
1 GW
Discharge rate seems to be the major life deciding factor.
OP (electricbike) plans on a 4A charge\discharge cycle test soon.
This should indicate whether charge rate is a major factor.
LiFePO4 typically has a lower discharge rate capability ... seemingly enforcing lower C (less damaging) discharge rates = longer life!
OP (electricbike) plans on a 4A charge\discharge cycle test soon.
This should indicate whether charge rate is a major factor.
LiFePO4 typically has a lower discharge rate capability ... seemingly enforcing lower C (less damaging) discharge rates = longer life!
electricbike
100 W
Uppdated 300 cycles.
I have also got my 2 extra Reaktor chargers just now, so i will start with Drkangels request very soon.
I will cycle thru the 5 cells a couple of times before i start his test.
I have also got my 2 extra Reaktor chargers just now, so i will start with Drkangels request very soon.
I will cycle thru the 5 cells a couple of times before i start his test.
wesnewell
100 GW
The major problem with this test is that it doesn't account for time. Batteries degrade with time and fluctuation of temps too. 300 cycles in a few days does not equal 300 cycles over a year or more where the temps change constantly.
DrkAngel
1 GW
Well, a real would test at 1C charge\discharge might take 3 years of daily cycling.wesnewell said:
By which time, this model cell will likely be obsolete ... replaced with upgraded model.
So I say, glean what info you can get!
Ohbse
10 kW
Great work keeping us updated on the progress. It certainly appears that the often talked about NCA 'plateau' is real - we would need a ton more data to characterize it accurately, will be very interesting to see if the rate of degradation drops even further.
Does the unit you're using track IR of the cell?
Does the unit you're using track IR of the cell?
electricbike
100 W
The Turnigy Reaktor has a function to measure IR but i don't think it is so accurate.
electricbike
100 W
Uppdated 320 cycles.
electricbike
100 W
Drkangel: Test1 i done, hopefully this is something you can use.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high)
4.15V >>> 3.10V @ 2.5A (Your test voltage, as control)
4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment inr18650-cell1-test1 1) Discharging.xls
View attachment 3
View attachment 2
View attachment 1
View attachment inr18650-cell5-test1 5) Discharging.xls
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high)
4.15V >>> 3.10V @ 2.5A (Your test voltage, as control)
4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment inr18650-cell1-test1 1) Discharging.xls
View attachment 3
View attachment 2
View attachment 1
View attachment inr18650-cell5-test1 5) Discharging.xls
Attachments
DrkAngel
1 GW
Charge-Discharge Range vs Capacity - Samsung INR18650-25R
OEM charge-discharge voltages (4.20V - 2.50V) charted
Took a while to figure good method of graphing.
Looks OK?
Will expand capacity lower as needed.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (electricbike test voltage +OEM high)
Test3: 4.15V >>> 3.10V @ 2.5A (electricbike test voltage, as control)
Test4: 4.15V >>> 2.50V @ 2.5A (electricbike test voltage + OEM low)
Test5: 4.10V >>> 3.30V @ 2.5A (DrkAngel derived optimal 1C C\D rate)
OEM charge-discharge voltages (4.20V - 2.50V) charted
Took a while to figure good method of graphing.
Looks OK?
Will expand capacity lower as needed.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (electricbike test voltage +OEM high)
Test3: 4.15V >>> 3.10V @ 2.5A (electricbike test voltage, as control)
Test4: 4.15V >>> 2.50V @ 2.5A (electricbike test voltage + OEM low)
Test5: 4.10V >>> 3.30V @ 2.5A (DrkAngel derived optimal 1C C\D rate)
Attachments
electricbike
100 W
Yes, it looks ok Drkangel.
electricbike
100 W
Test 2 is done.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high) Done
4.15V >>> 3.10V @ 2.5A (Your test voltage, as control)
4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment inr18650-cell1-test2 ) Discharging.xls
View attachment inr18650-cell2-test2 ) Discharging.xls
View attachment inr18650-cell3-test2 ) Discharging.xls
View attachment 1
View attachment inr18650-cell5-test2 ) Discharging.xls
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high) Done
4.15V >>> 3.10V @ 2.5A (Your test voltage, as control)
4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment inr18650-cell1-test2 ) Discharging.xls
View attachment inr18650-cell2-test2 ) Discharging.xls
View attachment inr18650-cell3-test2 ) Discharging.xls
View attachment 1
View attachment inr18650-cell5-test2 ) Discharging.xls
DrkAngel
1 GW
#2 test of 5 in series, completed and charted.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (electricbike test voltage +OEM high) Done.
Test3: 4.15V >>> 3.10V @ 2.5A (electricbike test voltage, as control)
Test4: 4.15V >>> 2.50V @ 2.5A (electricbike test voltage + OEM low)
Test5: 4.10V >>> 3.30V @ 2.5A (DrkAngel derived optimal @ 1C C\D rate)
(Cell Test # lines are rough guess - properly positioned at average of tests cells, after each test completed)
Most notable, so far ...
1. Discharging to 2.50V greatly amplifies the divergence in cell capacities
2. 2.50V to 3.10V appears to contain <8% of total capacity
(155% discharge depth = 108% capacity)
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (electricbike test voltage +OEM high) Done.
Test3: 4.15V >>> 3.10V @ 2.5A (electricbike test voltage, as control)
Test4: 4.15V >>> 2.50V @ 2.5A (electricbike test voltage + OEM low)
Test5: 4.10V >>> 3.30V @ 2.5A (DrkAngel derived optimal @ 1C C\D rate)
(Cell Test # lines are rough guess - properly positioned at average of tests cells, after each test completed)
Most notable, so far ...
1. Discharging to 2.50V greatly amplifies the divergence in cell capacities
2. 2.50V to 3.10V appears to contain <8% of total capacity
(155% discharge depth = 108% capacity)
electricbike
100 W
Uppdate -380 cycles.
parabellum
1 MW
It just passed 10% capacity decrease mark. Not bad for 380 cycles.
DrkAngel
1 GW
electricbike
100 W
Yes they are 2500 mah cells.
electricbike
100 W
Test 3 is done.
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high) Done.
Test3: 4.15V >>> 3.10V @ 2.5A (Your test voltage, as control) Done.
Test4: 4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
Test4: 4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment INR18650-25R-cell 1) Discharging.xls
View attachment INR18650-25R-cell 2) Discharging.xls
View attachment INR18650-25R-cell 3) Discharging.xls
View attachment INR18650-25R-cell 4) Discharging.xls
View attachment INR18650-25R-cell 5) Discharging.xls
Test1: 4.20V >>> 2.50V @ 2.5A (Similar to OEM test voltage) Done.
Test2: 4.20V >>> 3.10V @ 2.5A (Your test voltage +OEM high) Done.
Test3: 4.15V >>> 3.10V @ 2.5A (Your test voltage, as control) Done.
Test4: 4.15V >>> 2.50V @ 2.5A (Your test voltage + OEM low)
Test4: 4.10V >>> 3.30V @ 2.5A (My derived optimal 1C C\D rate)
View attachment INR18650-25R-cell 1) Discharging.xls
View attachment INR18650-25R-cell 2) Discharging.xls
View attachment INR18650-25R-cell 3) Discharging.xls
View attachment INR18650-25R-cell 4) Discharging.xls
View attachment INR18650-25R-cell 5) Discharging.xls
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