[rant] If A123 cells are so great....

wb9k said:
Limited experimental runs of other sizes are possible, but I have no awareness of anything in that size. It can't be ruled out, not be me anyway.

Could have also been B-grade (or worse) 20Ah cells. Bear in mind there is normal variability in there too. The officially stated nominal capacity of the "20 Ah" cell is 19.6 Ah, but the very best ones will weigh in at 21 Ah.

I would believe that the large quantity of 20ah and 16ah cells I bought from cellman in 2009 were experimental or preproduction - and he only ran out of them because my second order bought every 20ah and 16ah cell he had left.  While most of the cellman 20ah cells were the same dimensions as the 20ah cells still sold today, some were thicker/wider/shorter like a123 was experimenting with the form factor, but still yielded the same weight and 20ah+.

The 16ah cells are identical to the 20ah cells, obviously made on the same machine, with the same tab layout, same materials, same discharge curves, the only difference being shorter/narrower/thinner/lighter, as if a123 was experimenting with which capacity to bring to market. The 16ah had similar WH/kg to the 20ah, so they were were not degraded 20ah cells.  I'm not sure why cellman called them as 15ah, as they all gave me >16ah. 

CLICK HERE for my comparison of spare 16ah and 20ah cells I got from cell_man, to 20ah cells I got from Victpower.   The very last picture in that post shows the Made in Korea label on a 16ah cell - can you identify anything of its provenance from the labeling?

-JD
 
oatnet said:
I would believe that the large quantity of 20ah and 16ah cells I bought from cellman in 2009 were experimental or preproduction - and he only ran out of them because my second order bought every 20ah and 16ah cell he had left.

Sorry Oatnet, you bought your cells in 2010 not 2009. Cellman just started offering these cells in the last half of December 2009, which for all practical purposes is a 2010 offering.

Also, I can find no build threads or posts with you using *any* experimental A123 20Ah cells for battery builds between the years 2010 to the end of 2011.

Can you show us your posts or build threads using *any* of the experimental A123 20Ah cells and NOT the smaller sized lower capacity 16Ah/15Ah cells you obviously used and posted a lot about?

Thanks. :wink:
 
I'd have to say these were from experimental builds. The cells look like the real thing, but the part numbers on them are very strange, and looking them up in our system yields no results. That, and the 400g weight called out by Oatnet suggests to me these were experimental builds of lower Ah cells, possibly precursors to the 14Ah cell I'm familiar with today. The odd dimensions of some cells rings true as well--I've seen stuff like that around the office before. Any marks on the center of the cells' front faces, or does the linked photo show all the markings on these?
 
wb9k said:
I'd have to say these were from experimental builds [...] possibly precursors to the 14Ah cell I'm familiar with today.

Just for comparison purposes what is the cell weight and dimensions of the 14Ah cells made today???

Here is the Korean experimental cell info:

Capacity: 15Ah

Size: 6.8mm x 150mm x 211mm

Weight: 400g

Thanks. :)
 
Outer dimensions are same as the 20Ah cell, only it's thinner. Not sure what the weight is offhand.
 
wb9k said:
I'd have to say these were from experimental builds. The cells look like the real thing, but the part numbers on them are very strange, and looking them up in our system yields no results. That, and the 400g weight called out by Oatnet suggests to me these were experimental builds of lower Ah cells, possibly precursors to the 14Ah cell I'm familiar with today. The odd dimensions of some cells rings true as well--I've seen stuff like that around the office before. Any marks on the center of the cells' front faces, or does the linked photo show all the markings on these?

It's been 3+ years since I built the 20ah and 16ah cells from cellman into packs, so my memory might be faulty but I don't remember any markings in the center. I might still have a 16ah cell I saved as a replacement, if so I'll take another look at it - would it be another stamp like the upper label, or something else?

I've been so focused on using the 28s3p/7s3p a123 prisimatic factory modules in cars and motorcycles, that I must have lost sight of the single-cell market, because this is the first I've heard of 14ah prisimatics. :shock: I preferred the smaller 16ah cell on ebikes, because I could build a lighter pack and my duty cycle didn't need 20ah anyhow. Seems to me that a 14ah version of the 20ah/16ah prisimatics would be a sweet spot in the tradoff of built weight vs capacity - at least for my design criteria. I'll have to see if I can source some to play with, thanks for the data point. :D

-JD
 
wb9k said:
Outer dimensions are same as the 20Ah cell, only it's thinner. Not sure what the weight is offhand.

That makes good sense to standardize on the same form factor as the 20Ah to use some of the same manufacturing equipment and material sizes.

PRICES need to come down! Hey, and that is my rant. :twisted:
 
The markings in the center of the cell that I'm referring to is normally a large letter and number and a 3-D barcode. On the 14Ah cell they would say "HEV" and have the 3-D barcode. At least that's what the more recent ones look like. The 14Ah cell is our "power" cell where the 20Ah is the "energy" cell. The smaller cell is meant to be aimed more at demanding HEV applications where lowest possible impedance is most desirable for max charge acceptance during regen. The larger cell will ultimately be aimed more at pure EV's and PHEV's where capacity is added for a slight sacrifice in cell impedance. This kind of thing appears to be becoming a fairly standard practice among battery makers these days.
 
Now you guys got me in trouble and Megacycle has woken up and contacted me for a % of Mega wrap profit. You have woken thge mega gaint and my profit's. The tea was too weak.
 
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