12S8P 30q cells experiencing voltage sag?[solved] (fake cells)

ESK8 Electronics
42

You should investigate if you have a P-group not working properly before you 100% write this off as fake cells

43

Already did that, there is a tag in one of my postā€¦ 1 p group was lower by .3 v. Checked each cell in that group and none dead. Just let it balance charge for awhile now its less than .1v low from the highest p group

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44

I think the range is okay. Granted ive only been on 2 rides, combined maybe 5 miles and indicator still says 100%. But i need to ride more first

45

How exactly is the pack built? you may not have fake cells. You may just have bad connections between cells in the same p group.

If the pack is welded, check for broken welds. If youā€™re using compression modules or somethign else, make sure everything is snug. Its possible for a shitty connection to carry charge current just fine then totally shit out on discharge. Iā€™ve even seen this with bad welds.

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46

It uses nese modules so not a bad connection

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47

iā€™m familiar with those, theyā€™e compression modules. While unlikely that it is a bad connection, i would still recommend removing the cells and cleaning the contacts with a solvent like alcohol.

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48

im using the nese modules. They are connected with 3/8 in thick copper flat stock and bolts, i bought new hardware to make sure i had several threads on the bolts and everything is snug

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49

If i have time i suppose i could do this sometimeā€¦ all 96 lolā€¦i inspected every cell and tab before i put it all together. i highly doubt there is any contact issue

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50

Here is a few suggestions:

  • like a lot of people said: bad p-group
  • ā€œabsolute max in vesc settingsā€ change it back to 130
  • donā€™t know if youā€™re using bms for discharging but you should really change the battery cut off voltage end to minimum 37,2V. For the longest life span I suggest 40,8V
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51

also i added picks of the cells im using at the top

52

If itā€™s sagging crazy it should also be getting hot. If bad contact, the connetors and bus bars and cell top/bottom would get hot first. If weak cells maybe the cell bodies get hot first.

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53

Read a bit in here

There you can find some examples how to find out from the optic if itā€™s real or fake cells.

I canā€™t see it proper on the pictures you uploaded, but it looks like the second ring is missing and also the inprint on the top. But you can check it better by your own.

54

20181203_125009 20181203_125005 slightly better pics, but i do see what you mean by missing a ringā€¦ i hadnt caught thatā€¦ damn

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55

if you can, remove the wrapping, there should be markings from the plant where they are made. Fakeā€™s usually donā€™t have them.

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56

No markingsā€¦i think i got fakes guys. Well damn 20181203_125814 20181203_125800

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57

Definitely fakes, canā€™t you send them back? or do a charge back or your card?

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58

damn brother

59

i bought them like a year agoā€¦ i highly doubt a return is possible. ill look into though Actually got them in June, and i just tried to contact the seller

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60

iā€™ve been using liionwholesale.com and imrbatteries.com for the past 3 years with zero issues. If you end up replacing your cells, i would suggest using one of those two, but compare prices. Often one has batter prices than the other, and on any given day it could be either.

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61

Was just about to buy some from thisguyhere his website esk8life.com has a sale going on. Thoughts?

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