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Identifying 18650 cells
#1
Hi everyone! I've been following this forum for a while, and I'm finally going to adventure myself in building a powerwall .
So i found a guy thats selling me a bunch of 18650 cells 50€ per pack, each pack is 10s5p, so 1€ per cell, good right? Specially from where I am (Portugal) it's difficult to harvest cells for a good price.

So before buying all of is cells I bought 1 pack and I'm going to test capacity with liitokala 500s (just started)

But I didn't find the specs for these cells, does anyone know or have any idea?
 
I can only see - "GPHN 18-25P 18k26Z 649212" 
Thanks
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#2
Sometimes its just not clear. I have some cells out a Fujitsu laptop pack (from many years ago) that I could not identify. To some extent, if they are for a powerwall then testing them at the ma you plan to use them should be sufficient for a decision to use / not-use.

If you just can't get any info you can also peel off the wrapper and see if anything is labeled directly on the metal casing - which might provide a clue.
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#3
25P implies a 2500mAh rating.

The casing is the same color a Canadian brand uses, but the other markings are not the same.

GPHN is a Thai brand, they also have 2600mAh batteries on sale. I did not practically test any of their models to see if the stated capacity is real or not, but give the stated 35g weight I think we deal with ultrafire-like fakes.

You should test if for capacity.
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#4
Hi, thanks for your opinions, I have tested 8 of them and have around 2700mAh, so maybe they are rated 2500mah (25p) and have nominal 2700 or higher? since they are used....
I'm really quite wondering what to do now..don't want to bet a bad bunch of cells on a powerwall.
Thanks anyway
By the way I can't get my eyes on any GPHN battery full specs did you find any?
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#5
Can you weight one ?
If they are authentic and branded 2500mAh, yes, it is possible to measure 2700, specially if you use a current lower than it's spec. What did you use for testing ?

As for the specs, I did see some time ago the pdf spec sheet for a 2600mAh one. Too bad I did not take a picture.
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#6
They could be rebranded cells from one of the big manufacturers. I had some cells that were labelled "ASO" but I found out that they were rebranded Samsung cells.
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#7
In such cases it's useful to determine if they re-brand new ones or used one.
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#8
(01-20-2020, 08:01 AM)Overmind Wrote: Can you weight one ?
If they are authentic and branded 2500mAh, yes, it is possible to measure 2700, specially if you use a current lower than it's spec. What did you use for testing ?

As for the specs, I did see some time ago the pdf spec sheet for a 2600mAh one. Too bad I did not take a picture.


Yes, they weight 45g, some 44g, it seems legit.
for current i used 0,5A and 0,7A and had consistent results for both.
you think it means they are rated 2500mAh? like in nominal?

Not knowing the max charge and discharge rate, I think it's better to built it in a bigger paralel pack just to be sure they won't overcome the unknown maximals.
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