SamTexas
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This SLA would not last past 50 cycles if used this way. Should have stopped and recharged at 4Ah max.DrkAngel said:SLA (10Ah) - expended in 1 hour = 6.14Ah *
This SLA would not last past 50 cycles if used this way. Should have stopped and recharged at 4Ah max.DrkAngel said:SLA (10Ah) - expended in 1 hour = 6.14Ah *
22.2V (25.2V full charge) might sound pretty wimpy compared to to oem 24V SLA (26V+ full charge).DrkAngel said:I decided to rebuild all my 2008 era "homemade" 18650 packs. ...
5. The builds (eZip pack capable)
a. 22.2V - 6s16p 96 cells 22.2V 41.6Ah 923.5mAh
b. 33.3V - 9s8p 72 cells 33.3V 20.8AH 692.64mAh +9s1p 5700mah RC Lipo 5.7AH 189.81MaH = 26.5AH 882.45MaH total - Hybrid Pack
c. 44.4V - 12s8p 96 cells 44.4V 20.8Ah 923.5mAh
I have a few brand new Panasonic cells I use for reference. The rest (over a thousand) are recycled. My recycled cells have an average of 75% of their original capacity. Any cell with less than 60% are discarded or set aside for lighter duty uses (flash lights, head lights, voltmeters and air pumps.)spuzzete said:Thank you Sam Texas for the info! I always try not mistreat my cells, it's nice to know that they can go as low as 2.5V! Are your cells recycled or new?
Having a graph makes it really easy to understand if the cells are good or not. Laptop cells don't like to be discharged over 1C, and even at 1C some don't perform well. I am going to run a bunch of tests at 0.5C or lower on laptop cells that didn't pass the tests.
The only negative thing of the CBA is that you need a computer to run the tests..I will probably buy a cheap netbook/laptop only for that purpose.
Anyway, here is a discharge test of the Sony Konion cells, those are LiMn cells, 18650 format 3.7v 1500mAh for each cell. The cells are connected in parallel, so the battery is a 1s2p 3.7v 3000mAh nominal.
You are forgetting that we tested our cells at a more realistic discharge rate of 1C. I stopped my test at 2.50V. Within 30 seconds the cell voltage jumped back to 3.2 to 3.5V, depending on brand and model. I would never have your patience or time to perform a 0.2C test.DrkAngel said:I just became concerned with the talk of expending to 2.5V! I tested these different cells to the point of no more usable energy - imo.
I have many used notebook battery packs.SamTexas said:Yes the common wisdom has always been longer life for shallower discharge. But it's one of those things that we choose to accept without verification. I certainly don't have the time, money and patience to spend a few dedicated years to prove or disprove that wisdom.
Since these particular cells show good capacity at a full 4.2V (pink line) I don't foresee any point.SamTexas said:You might also want to investigate the effect of the upper voltage limit as well. i.e. 4.10 versus 4.15 versus 4.20V
That's another problem with these wisdoms. We tend to choose to accept only what we want to hear, what best fits our needs.DrkAngel said:Since these particular cells show good capacity at a full 4.2V (pink line) I don't foresee any point.
I believe that damage, reduced capacity, is caused by needlessly draining where there is minimal energy stored.
Capacity is the measure of longevity.SamTexas said:Capacity is not the question here. Longevity is. The pink LiCo 18650 is the one that needs to be investigated most. How much longer would it last if some of the upper capacity is sacrificed.
Never intended to recommend 3.6V as LVC.spuzzete said:@ DrkAngel
On my test on the Panasonic CGR18650CG (4.4Ah) @ 0.2C 3.6v is way too safe as LVC. in the test under load the cells give less than half the nominal capacity @3.6v (about 2.0 Ah), the lowest "useful" point is about 3.35v (3.9Ah), after that there is very little capacity/energy left in the cell.
Other cells (Panasonic CGR18650D) show similar behaviour, with useful capacity up to 3.4-3.35v (But test @ 0.5 C this time).
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spuzzete said:@ DrkAngel
On my test on the Panasonic CGR18650CG (4.4Ah) @ 0.2C 3.6v is way too safe as LVC. in the test under load the cells give less than half the nominal capacity @3.6v (about 2.0 Ah), the lowest "useful" point is about 3.35v (3.9Ah), after that there is very little capacity/energy left in the cell.
Other cells (Panasonic CGR18650D) show similar behaviour, with useful capacity up to 3.4-3.35v (But test @ 0.5 C this time).
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