electricbike
100 W
First test uppdated 660 cycles.
Samsung INR18650-25R cycle test.
- Thread starter electricbike
- Start date
parabellum
1 MW
How did you got this one?eTrike said:
electricbike
100 W
parabellum said:
2500 mah-24,6%=1885 mah.
parabellum
1 MW
OK.
Maybe its better to go the other way to avoid confusion? Like resting 4.15-3.1V capacity VS rated 4.2-2.5V = 75.4%
Maybe its better to go the other way to avoid confusion? Like resting 4.15-3.1V capacity VS rated 4.2-2.5V = 75.4%
electricbike
100 W
Uppdate difference test 320-440 cycle.
DrkAngel
1 GW
- Tally ... so far:
- 4.0A charge\20A discharge ... 10% loss @ 47 cycles 20% loss @ 112 cycles
- 2.5A charge\2.5A discharge .. 10% loss @ 377 cycles 20% loss @ 1000+? cycles
- 2.5A charge\5.0A discharge .. 10% loss @ 325 cycles 20% loss @ 700+? cycles
- 4.0A charge\5.0A discharge .. 10% loss @ 190 cycles 20% loss @ ~460 cycles
Rated by capacity loss %
Discharge rate is an obvious degradation factor!
Now, it is becoming obvious that charge rate is also a major factor!!
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I'm going to run some tests on 3500 MAH cells soon.
What I think I will do differently is every 40-50th cycle I will run a single charge/discharge (4.2volts to 2.5volts) at an extremely low rate like .25 amp charge .5 amp discharge to be able to graph the results more accurately and to be better gauge exactly how much capacity is in the cell.
So the first charge/discharge at .25/.5map should be around 3500MAH, then the 40th at that rate will be something like 3450MAH. So You can exactly see what is in the cell.
I will charge exactly to 4.2 to 2.5 or whatever voltage it takes to get 3500 MAH on the 1st cycle, then the 40th cycle will do the same exact 4.2 to 2.5 volt cycle.
What I think I will do differently is every 40-50th cycle I will run a single charge/discharge (4.2volts to 2.5volts) at an extremely low rate like .25 amp charge .5 amp discharge to be able to graph the results more accurately and to be better gauge exactly how much capacity is in the cell.
So the first charge/discharge at .25/.5map should be around 3500MAH, then the 40th at that rate will be something like 3450MAH. So You can exactly see what is in the cell.
I will charge exactly to 4.2 to 2.5 or whatever voltage it takes to get 3500 MAH on the 1st cycle, then the 40th cycle will do the same exact 4.2 to 2.5 volt cycle.
DrkAngel
1 GW
Offroader said:
(INR18550-25R)
Be aware that a 4.20V to 2.50V (@20A) might discharge cell to a static 3.40V (effectively "empty") for the full rated 2500mAh.
Discharging to the same 2.50V at (@.25A) might discharge to a very damaging, for minimal additional capacity, static 2.55V?
Link to a typical discharge graph? ... can estimate probable static "empty" voltage.
DrkAngel said:
thats the problem with such tests. THE CURRENT VARIES in common practice and how the batteries are used on vehicles.
optimal would be a controller with two adjustable LVC and two cut off current settings.
for instance at 100A the voltage is allowed to sag to 2,5V per cell and at 5A it cut off at 3,2V per cell. everything between is linear like at 50A it will allow to sag to 2,85V
this would mean we have full power or can drain full amps down to our defined 0% soc, while keeping cycle life high.
at the moment this must be watched and adjusted by the rider and it's only possible to have either high power until empty, or high cycle life, but not both.
normally i have set LVC to 3,1V, but this means below 20-30% SOC i cannot drain full current anymore because lvc is reached and the adaptto controller starts to limit the currrent to prevent further sag (nice and smoothly). if i now adjust to 2,5V i can use much longer full amps, but it will worsen cylce life if i than run the battery completely empty.
Thanks Drkangel, I'll have to look more into the range when I get the cells in the mail. I actually never have run any lipo battery yet more than the safe limits, which for my lipo is 4.1 to 3.7.
I shut off my LVC long ago after I was showing off climbing this really steep hill in front of a college and the LVC kicked in causing me to have to jump off the bike while in the middle of the steep hill.
I shut off my LVC long ago after I was showing off climbing this really steep hill in front of a college and the LVC kicked in causing me to have to jump off the bike while in the middle of the steep hill.
electricbike
100 W
Uppdated difference test 400-520.
Skrzypas
10 W
Coming back to the earlier discussion, there are two parameters different between both tests: charging current (2,5 vs 4 A) and cut off current (0.025 vs 0.040 A).
We observe:
1. Lower capacity with higher cut off current which is obvious,
2. Faster decrease of capacity for higher charge current (distance between both lines is increasing to the right on the graph), that was expected.
3. The effect of 4/2.5=1.6 higher charge current has stronger influence on degradation than the positive effect of 0.040/0.025=1.6
times higher cut off current.
Unfortunately we will not be able to determine cut off current degradation that is connected to electrode plating during extended 4,15 V charging.
Guys (electricbike and da) , I'm impressed with your tests and reasoning!
We observe:
1. Lower capacity with higher cut off current which is obvious,
2. Faster decrease of capacity for higher charge current (distance between both lines is increasing to the right on the graph), that was expected.
3. The effect of 4/2.5=1.6 higher charge current has stronger influence on degradation than the positive effect of 0.040/0.025=1.6
times higher cut off current.
Unfortunately we will not be able to determine cut off current degradation that is connected to electrode plating during extended 4,15 V charging.
Guys (electricbike and da) , I'm impressed with your tests and reasoning!
electricbike
100 W
Uppdated cycletest 860.
DrkAngel
1 GW
DrkAngel
1 GW
Read "Legend".madin88 said:
Lower left in graph.
cwah
100 MW
This blog is doing comparison:
http://batterybro.com/blogs/18650-wholesale-battery-reviews/35187011-green-samsung-18650-25r5-vs-blue-25r2
http://batterybro.com/blogs/18650-wholesale-battery-reviews/35187011-green-samsung-18650-25r5-vs-blue-25r2
electricbike
100 W
Uppdated differencetest 600-800. Actually it looks a bit strange.
DrkAngel
1 GW
electricbike
100 W
Just got 4 29E cells from a ES member that i will start some cycle test at in the next week.
2 more chargers ordered also.
Will start a new topic on those cells.
2 more chargers ordered also.
Will start a new topic on those cells.
electricbike
100 W
Uppdate difference test 720-960.
Wheazel
10 kW
electricbike said:
Very much looking forward to this!
Where in Sweden are you located?
DVDRW
100 W
Me too!Wheazel said:
electricbike
100 W
Wheazel said:
I am located in Lund.
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