Those are freaking cool! I would love to use them for a low-profile system in my tiny camper trailer. Super easy to mount under a bed or chair, or even tucked down into the frame.
Cylindrical cells 100AH
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curiouscarbon
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THANK you for noting the loose packing condition.
Loose Means Distance To Accelerate.
Batteries Hate Acceleration! Ow.
LiCurious
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Ok, 1st cell test completed. Charged @ 20A to 3.65V until current dropped to 0.05C or 5A. Then discharged @ 20A to 2.50V. The charge/discharge voltages and charge termination current are per the datasheet. This yielded 99.34Ah. Discharge graph is below.
Was the voltage at the cells terminals 2.50 volts when you stopped the test?
LiCurious
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yes, according to the battery load tester. i didn't verify independently with a multimeter.
on my discharge graph the left hand Y axis is voltage and the right hand Y axis is current. the test terminated at 2.50v and 20A.
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The voltage measured at the cell will most likely be a bit more due to voltage drop. My best guess is 2.6-2.7 volts and that's based on what others have reported. At that point the voltage is so low there won't be much capacity left.
You may have been able to get 100ah or a little more if measuring the voltage at the cell. I would say 99.34ah's is good and would suggest you test the other cells the same way to find out if the capacity of each cell is close to the others. But also report the voltage at the cell when the capacity tester ends the test.
LiCurious
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sure, i'm currently discharge testing cell #2 and i am measuring about 70mV across each current carrying lead. that would suggest about 2.64V at the cell when the load tester sees 2.50V. in practice i won't be concerned with extracting every last Ah out of the cells so 99.34 is close enough for me.
LiCurious
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ok, silly me forgot about the "plain as the nose on my face" fact that my load tester uses 4 wire sensing so the voltage drop across the current carrying leads does not affect the voltage measurement at the cell. i hooked up my multimeter in min/max mode to the cell terminals and captured a min reading of 2.504V when the load tester terminated the test. cell #2 yielded 99.67Ah.
LiCurious
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now to make things even more interesting... after 2 months of waiting to receive my 100Ah cylindrical cells from china, i started to consider other possibilities and as a "plan b" i decided to try some 55Ah cylindrical cells being offered by a domestic battery seller. while the 55Ah cells were in transit to me i finally received my 100Ah cells. now my workbenches runneth over with cells! anyways, i will post my observations and test results for the 55Ah cells here unless the masses feel that a separate thread is warranted. below is a side by side pic of the 100Ah and 55Ah cells. what i find interesting is that the two cells are almost the same size but have a large difference in rated capacity.
curiouscarbon
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i wonder why that is!
headway has a cylindrical high power and high energy density cylindrical cells but it’s only 20% difference capacity for same volume.
looking forward to checking out any data or analysis you post in the future
Your first test is quite what I was hoping for this cells.
If you are able to test at least another one with similar results, I will be ready to order 20 to build 500Ah 12v.
I am thinking ordering 21-22 to discard the worse one, what is your advice?
If you are able to test at least another one with similar results, I will be ready to order 20 to build 500Ah 12v.
I am thinking ordering 21-22 to discard the worse one, what is your advice?
LiCurious
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before you place your order you should wait for an upcoming post from me that will discuss some of my observations on the physical condition of the cells as i received them.
LiCurious
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to recap my first post upon receiving the 100Ah cells from china: construction appears robust externally but all my cells arrived with dents/dings around the entire circumference of the outer shell at the negative terminal end. each cell was inside a single, thin bubble wrap sleeve and the overall packing inside the box was loose. the first pic below is an example of the dents/dings.
once the initial excitement of finally having the cells wore off, a calmer and more thorough examination revealed that one of the cells also has a compressed spot of the outer shell at the positive terminal end. the positive terminal is slightly recessed as well when compared to an undamaged cell. the second pic below shows the compressed cell vs an uncompressed cell.
i don't know which imperfections are shipping related and which imperfections are manufacturing related. it is plausible that the dents/dings were caused by the cells bumping each other in shipping since the packaging was not tight. however, i have a harder time attributing the cell with the compressed end to shipping damage. the cells were packed parallel to each other so the only things the compressed end could bump into were the packing foam and the box. i did not see any evidence of the cell terminal perforating the box. the terminal threads were not damaged and neither was the vinyl cap covering the terminal threads.
i am most concerned about the cell with the compressed outer shell. it capacity tested good but who knows if there is some compromise to the internal structure that will affect longevity.
once the initial excitement of finally having the cells wore off, a calmer and more thorough examination revealed that one of the cells also has a compressed spot of the outer shell at the positive terminal end. the positive terminal is slightly recessed as well when compared to an undamaged cell. the second pic below shows the compressed cell vs an uncompressed cell.
i don't know which imperfections are shipping related and which imperfections are manufacturing related. it is plausible that the dents/dings were caused by the cells bumping each other in shipping since the packaging was not tight. however, i have a harder time attributing the cell with the compressed end to shipping damage. the cells were packed parallel to each other so the only things the compressed end could bump into were the packing foam and the box. i did not see any evidence of the cell terminal perforating the box. the terminal threads were not damaged and neither was the vinyl cap covering the terminal threads.
i am most concerned about the cell with the compressed outer shell. it capacity tested good but who knows if there is some compromise to the internal structure that will affect longevity.
Turponieminen
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Probably these are grade b cells.
Most likely they are cells that manufacturer sells at discounted price to this Alibaba battery vendor because they have external damage. How ever It would mean they are new cells.
Most likely they are cells that manufacturer sells at discounted price to this Alibaba battery vendor because they have external damage. How ever It would mean they are new cells.
Keith_PDX
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Did you reach out to the vendor and show the pictures and get their input? May be a useless endeavor but I am curious what they said, if anything...
Keith_PDX
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@LiCurious Can you tell me what the dimensions of the black cell holder are? I am curious how large a pack like the one on their website would be.
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