Brand new 3000Mah LG 18650's only charging to 2400Mah?

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So heres the story. I purchased 270 LG HG2 cells from Alibaba (i realise it's probably not a great idea to buy cells from Alibaba). after the cells arrived roughly 2 weeks later i have tested 4 so far and even after fully discharging the cells twice and then charging them all the way up to 4.2volts the highest capacity i have gotten from one of the cells so far is 2480Mah, considering the LG HG2's are rated for 3000Mah this seems pretty poor to me. I feel like its worth mentioning i'm charging the cells with a genuine Imax b6ac charger, I first tried charging the cells in the LI-ION mode on the charger but it would only charge the cells to 4.1v, so i changed the charger mode to LI-PO and its now charging the cells to 4.2v, yet even when charging the cells to 4.2v the highest Mah i have gotten as i said before was 2480. I would also like to say that as far as i can tell the cells are completely genuine. I have seen that the fake cells usually have sloppy folding and cutting on the button top of the cell, yet these cells seem fine. and the wrapping looks to be very clean to, What do you guys thing?, are they real HG2 cells that have just been stored really wrong, or could they be re wrapped cheaper cells or he4's, am i charging them wrong somehow?, thanks

Also heres some photos of the cells and charging:
http://imgur.com/a/E9LM4
http://imgur.com/a/281sb
http://imgur.com/a/Eb6xx
http://imgur.com/a/BiQyb

 

[Overclocker]

you didn't do a discharge test?

simply checking capacity isn't good enough. the only sure way to check for fakes is by comparing curves:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=87798&p=1281744

BTW there are TONS of HG2 fakes these days for the vape market

 

[amberwolf]

its now charging the cells to 4.2v, yet even when charging the cells to 4.2v the highest Mah i have gotten as i said before was 2480.

You'd have to do a discharge curve test to find out what their actual capacity and behavior is is.

To test for the same capacity as is claimed by the manufacturer, you also have to do the discharge test in the same way, so you'll have to check it's spec sheet for how they did the test.

If you test it differently, you can't compare the results directly, and would have to have a known-genuine cell to do your own test with to compare to the other cells you have there.

I would also like to say that as far as i can tell the cells are completely genuine.

Have you done a visual side by side comparison with genuine cells, both with and without the shrinkwrap on? Preferably in-hand, but short of that, using known-good photos to compare with?

And then you'd need to do an electrical comparison, using the manufacturer's spec sheets as a guide to how they tested them, repeating the same exact tests with your own cells.

After those all pass, then you could say with some confidence if they are or are not genuine. Without at least doing those tests, I would not be able to have any confidence in a declaration of genunineness.

I have seen that the fake cells usually have sloppy folding and cutting on the button top of the cell, yet these cells seem fine. and the wrapping looks to be very clean to,

Why would genuine cells have a sticker on them to show what they are? They already would have an imprinted marking that says that.

You don't show the cell under the shrinkwrap--without seeing that (and seeing that they are all identical under it) you won't know if they are the same as a genuine cell.

Boxes are easy to print, as are stickers and shrinkwrap.

Remember that fakes may use a "new" cap over a damaged one, held on with the faked shrinkwrap or tape or glue.

 

[wesnewell]

How did you test them? Capacity test are done at 0.6A, 25C degrees, from 2.5V - 4.2V. If you only went down to 3.0V and/or a higher charge/discharge rate for the test, 2500mah sounds about right.
http://lygte-info.dk/review/batteries2012/LG 18650 HG2 3000mAh (Brown) UK.html

 

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How did you test them? Capacity test are done at 0.6A, 25C degrees, from 2.5V - 4.2V. If you only went down to 3.0V and/or a higher charge/discharge rate for the test, 2500mah sounds about right.
http://lygte-info.dk/review/batteries2012/LG 18650 HG2 3000mAh (Brown) UK.html

I know it's now been more than a month since i started this thread (after finding out what i was doing wrong with the charger i completely forgot to report back here) but for anyone who sees this in the future the Li-Ion discharge mode on the IMAX b6ac charger does not discharge the batteries all the way to 2.5v. after changing the discharge voltage to 2.5v and current to .6a i got the full 3000mah