Quote:
Originally Posted by himalaya
Lincpimp I need a LiPo expert's help.
I bought a Hyperion pack from a stock clearance sale, really a great deal. You know Hyperion is busy introducing their new G3 and trying to close out the old Enerland based packs. The pack is brand new but may have been in store for some time period, I found the pack has problem in cell matching:
Pack: HP-LVX4350-6S, 25~40C 4350mAh
I logged the charge/discharge curve using a EOS0720i hooked to my pc and found
cell 2\3\5 has an internal resistance of about 3mΩ
cell 1\4\6 has an internal resistance of over 15mΩ
in other words, my 6S pack has 3 good 25C cells and 3 poor 5C cell mixed together.
I figured this by calculating the voltage drop during charge pause(3 seconds every minute) and the voltage rise during discharge pause(3 seconds every minute), with same result.
the cells doesn't show too much difference in capacity, all around 3950mAh(set discharge threshold 3.0V/cell) which is obviously 10% lower than it's expected to be(4350mAh).
So my questions are:
* is this problem due to long storage time ? capacity loss and IR increase.
* is there any way I can "activate" the bad cells to improve the IR ? something like high current impact\ slight overcharge/overdischarge or heat/freeze the pack?
Thanks in advance.
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Hmm, all I can say is to try to run the pack in a low-medium draw situation, and not remove much more than half capacity. Then charge each cell separately and see if they have discharged evenly, if so they should all have lost about the same amount of mah. I would not load the pack too much, as you may damage the weaker? cells... I will be interested to see what you come up with.
Quote:
Originally Posted by Hardstyle
lincpimp, have you checked my lipos yet 2 Robbe and 2 MA?
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Just found them in a box next to the desk so I will take a look at them tomorrow and get back to you. Sorry about the delay, been really busy.