Avoiding fake batteries - how?

dnmun said:

... lecture by JB Strausel ... talked kinda obliquely about his ideas about the future form factors.

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The original video link was removed, but I went to Youtube and devoured a few talks by Strausel . The bit about the 18650 form factor appears 45m25s in: https://www.youtube.com/watch?v=zWSox7mLbyE&t=45m25s

I think the gigafactory cells will be something like 21750 or 20750; 5000 mAh.
I am sure they will be pretty awesome...

If so, I wonder how much energy density Tesla would gain vs. just volumetric density. That change in form factor would imply a redesign of the skateboard. Presumably they would keep the basic attachment points for upgraders and battery swaps. Any hints about this from Musk or Straubel?

Hi!

I recently purchased some A123 ANR26650M1B cells from HK.

The cells delivered did not match the picures shown to me when ordering. There is no A123 logo, and the model number says "ANR26650" instead of "ANR26650M1B".

According to some info I found, they maybe be real A123 cells but B-grade. Rejected samples from the normal production line, not within specifications, and sold without warranty.

I filed a complaint to the seller, who claims that the cells are A-grade because B-grade cells have no barcode. He also claims that after A123 went bankrupt, virtually all cells on the market are without A123 logo.

I tested the cells and they deliver the stated capacity of 2.5Ah. Current handling is difficult to test due to the extreme currents over 100A.

Does anyone know what these cells are?

sven_nilsson said:

I recently purchased some A123 ANR26650M1B cells from HK.... He also claims that after A123 went bankrupt, virtually all cells on the market are without A123 logo.... Does anyone know what these cells are?

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Post a picture of the cells. Then PM wb9k the thread and ask him. With regards to "all cells on the market without A123 logo" claim, this is patently not true. Quite the opposite - all genuine A123 cells are labelled. The factories never stopped production during bankruptcy.

They look exactly like this

i was under the impression that A123 no longer existed and had been sold to a chinese company. so how could they now use the A123 label if the company that owns the rights to the label is now non existent?

Something that does not exist cannot hold rights on something that does exist

If it's a knockoff product, then they likely don't give two f***s who owns the rights to what.

Ark is right that A123 never stopped producing cells, even while in bankruptcy. To my knowledge, they have never produced unbranded cells either, not even B grade. These are probably knockoffs, but some high current testing would tell you for sure. Is there a barcode under the PET sleeve?

For the record, A123 was bought by Wanxiang USA over a year ago. A123 Systems Inc is now known as A123 Systems LLC. All intellectual property from the old A123 remains property of the new entity. A123 still very much exists.

My advice is avoid anything on ebay or China, and do your research based on feedback from people on this forum.

Keep in mind if you end up getting a bad battery shipping it back to China is virtually impossible.

Yes there is a barcode under the sleeve.

And not only that, there is also a somewhat faint printed text "A123 SYSTEMS" under it.

The following info is what made me believe it is b-grade cells:
http://e-motion.lt/wp-content/uploads/2010/04/A123_26650_Pirate_cell_report.pdf
http://www.multi-rotor.co.uk/index.php?topic=297.0

Interesting. The report appears to have been written by A123 personnel in the Chungzou (CZ) office about 4 years ago, just before I joined the company. I was at CZ a few months back, but not for very long. I still have yet to hold any unbranded A123 cell in my hands, but the report does appear to be real. Perhaps this is/was a practice only in China...it's news to me, in any case. Sounds like the can has "A123 Systems" laser-etched into it? That would indicate a genuine part to me, but now you have to determine what "B-grade" means. It CAN mean a whole array of things from totally benign to rather significant, partially depending on your application. The only way to really know if they're any good is to test them (to determine short-term capability) and then use them (to determine longevity).

why not post a picture?

dnmun said:

why not post a picture?

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Simply because I can find better pictures of my cells (that I know are the same) on the web. There is no chance to capture that laser etching using a cheap camera.

Anyway, now that you say the A123 report appears genuine, I see that this report falsifies the claim that B-grade cells have no barcode, because the rewrapped B cell in the report has a barcode underneath the logo...

sven_nilsson said:

Anyway, now that you say the A123 report appears genuine, I see that this report falsifies the claim that B-grade cells have no barcode, because the rewrapped B cell in the report has a barcode underneath the logo...

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OR...the cells you have were rejected by A123 completely, then wrapped by somebody else to make them look like B-grade. Gotta test them.

Thanks for the feedback. Yeah, these cells are an undefined entity at this time.

The only thing that I feel somewhat confident about is that they originate from an A123 factory.

They could also be A-grade cells that are being sold as B-grade because the chinese market does not have high enough demand for the pricey A-grade cells.

If I'm gonna do testing, it will be complicated by the fact that my cells are welded 8 in parallel which yields 1000 amps or more if the cells are genuine.

Nay, just ain't worth it. If you're pretty sure they are fake, then you can try to return them for a refund. Nixer is the return cost & shipping - li-ion and all. If you're not going to do that, then why fuss? Just put 'em in and use them. When they die, they die, maybe prematurely, maybe not. Take it as a lesson for when you're buying your second batch. FYI, I would only buy A123 from http://www.buya123batteries.com/ or http://osn.en.alibaba.com/. The former for guaranteed new, legit, genuine A123 direct from the factory. The latter for discounted, don't know, but good working cells & batteries.

sven_nilsson said:

... my cells are welded 8 in parallel which yields 1000 amps or more if the cells are genuine.

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I'm very curious about the means by which they are held together. Is this supposed to be A123's work as well, or just the cells. I'd like to see a pic...it may yield further clues about their origin.

if you need to test the current from one can then you can just open that parallel link and test one can, or two or three depending on your dummy load and the wattmeter you have available to record the Ah.

if you test just one cell then you can power the wattmeter from the auxiliary power source and see if it will read the cell voltage during discharge so you can swap out part of the dummy load to change the resistance and see how much the voltage changes.

you could sample cans at each end of the row and then do that to several of your parallel rows to increase the sample number to see if any info turns up in the Ri or capacity numbers to help understand why they were graded to B.

I'm not going to return them. This post was mostly to show what you can expect to get when ordering from a chinese source.

I don't need extreme amps either, I choose A123 because I was hoping for better cycle life and higher overall quality than the competition.

About my 1S8P welded packs, these were welded together by the factory I ordered from. They did a very good job, could hardly ask for any better.

spot welding these cans together in parallel is kinda the worst of all possible build beginnings.

there are manufacturers warnings about spot welding to the center of the case on the bottom end so that has reduced reliability to begin with. there is no need for a large parallel strap to connect the cans in parallel.

that is a poor way to build a pack because later when one channel develops a drain down problem it will be almost impossible to isolate the bad can out of all of those spot welded in parallel.

i hope others reading this can understand why making the parallel connection with large conductors is not needed and it is a big problem when it comes to maintaining the pack later.

the only large conductor needed is the serial link and not the parallel link.

the parallel connection should be with small wires so you can cut the parallel link open to isolate the can with the high drain down rate.

when it is a large metal strap it is very hard to cut and isolate the individual cans.

if you use a small 1mmx4mm cross section copper link to make the serial link then that is enuff to carry 40A from one can to the next in series.

then pretin the edge of the bottom of the case and the serial link and then reflow the individual little copper links serially when the cans are all assembled into the pack, and then use small 26AWG paralleling copper wire soldered to the middle of that serial copper link.

if you need to isolate one row for diagnosis, then it is easy to cut the parallel link open.

This is exactly why I bought lipo packs off Hobbyking, because as long as you are quick and give them a good testing within 30 days of receiving them, you can send them back again if you get a bad pack. I would have used individual cells, but the minefield involved I didnt fancy it in the end, and to be honest having 15 6s lipo packs in my bike makes it crazy powerful anyway and it has 45 miles range, so cant complain really, plus they are cheap as hell in comparison.

dnmun said:

spot welding these cans together in parallel is kinda the worst of all possible build beginnings.

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That's an awful broad statement that may or may not be true at all depending on one's requirements.