A123 B grade info

[arkmundi]

B grade I can handle, but defective is another matter. I have 31 cells that quite likely were made during the 1 in 4 are potentially bad time period, so my bottom line is how best can I force an early failure of the bad cells before I build a pack. If a cell is defective, what is the best way to force the issue...cycle under extra compression, cycle under no compression, cycle at high rates, ???

Nay, don't do that. Get some life out of them by putting them in a pack. Just need to make your pack so a cell that fails can be removed and replaced. Which, agniusm's kit did quite well for me.

 

[wb9k]

They did and they do.
The problem is the cells sanctioned for destruction entered the grey market.
Make no mistake, A123 handled the situation accordingly, all those cells are contractually marked for termination. The company has zero reason to inform the public which cells salvaged from oem packs passed through misscalibrated machinery.

I don't know why people think otherwise, just because you gave money to someone with another companys product markings doesn't entitle you to customer support.

Well put. A123 cannot be held responsible for supporting material it paid to have destroyed which has wound up on the grey-market through less-than-Kosher channels.

It's both amusing and annoying to watch the wild speculations about what the company knows and doesn't know unfold in these threads and see people who expect that I will give away the intellectual property of the succeeding company so they can continue to sort through what's left of the trash from the defunct one.

FWIW, we can tell which welder a cell went through, so, yes, we do know which cells may be affected by the tab misalignment issue without even having to look up the serial number in our system. It's not 100% of the throughput of that machine, BTW, and thus not 25% of the product built, but less than that. We have always had that level of traceability, and it has improved quite a bit since then. When talking about details of cell production, we're getting into a topic I'm not highly qualified to comment on, and also an area where it's better to keep quiet other than to say that things have improved significantly since the bankruptcy.

We have a very small inventory of B-grade pouches on hand and they are the result of hiccups we know about--two facts that taken together should speak well for what is happening in Livonia these days.

Back to the topic of B grade, buya123batteries.com had a special running on older 26650's that they were calling "B grade". I have speculated that they were A grade specimens of the older chemistry, and are now being called B grade because they are now an obsolete chemistry--but that's just my guess. I would confirm this with the seller, and if they say they were B grade before their chemistry was supplanted, then you'll have some idea of what that actually means.

I'm just trying to help, ok?

 

[John in CR]

B grade I can handle, but defective is another matter. I have 31 cells that quite likely were made during the 1 in 4 are potentially bad time period, so my bottom line is how best can I force an early failure of the bad cells before I build a pack. If a cell is defective, what is the best way to force the issue...cycle under extra compression, cycle under no compression, cycle at high rates, ???

Nay, don't do that. Get some life out of them by putting them in a pack. Just need to make your pack so a cell that fails can be removed and replaced. Which, agniusm's kit did quite well for me.

I don't want to get life out of faulty cells. I want to weed them out, leaving myself with a good quality, long life, high power pack that I don't have to piddle with, because I invested the time up front. This has worked well for me on every pack I've built. I just need to know what is the best way to get the faulty cells to show their colors, or in this case spots.

 

[arkmundi]

I don't want to get life out of faulty cells. I want to weed them out, leaving myself with a good quality, long life, high power pack that I don't have to piddle with, because I invested the time up front. This has worked well for me on every pack I've built. I just need to know what is the best way to get the faulty cells to show their colors, or in this case spots.

By putting them in a pack and using them. You could bleed the hell out of them over & over, but that approach makes no sense. Can't decipher the serial number. Best way is in a pack and monitor the cells. Overall the least time consuming approach.

 

[t3sla]

Back to the topic of B grade, buya123batteries.com had a special running on older 26650's that they were calling "B grade". I have speculated that they were A grade specimens of the older chemistry, and are now being called B grade because they are now an obsolete chemistry--but that's just my guess. I would confirm this with the seller, and if they say they were B grade before their chemistry was supplanted, then you'll have some idea of what that actually means.

I'm just trying to help, ok?

I believe that.
Another LiFePo4 supplier recently improved their chemistry (boosting each cells capacity slightly), but they never bothered to changed the model number.
They didn't seem to understand lingering old stock might exist, so now there are two identical cells which different capacity (only way to check is by s/n)
You can imagine what that might mean for a second tier pack builder who is sloppy..... :?

SO it's good to see the seller isn't using the cut-in method to dispose of the dated cells and instead being honest and marking them down separately
It's the things you don't do in the battery business that set you apart

 

[wb9k]

The bad news is, once you have the electrolyte in contact with the middle aluminum layer inside the laminated foil composing the pouch, you are just playing the waiting game until pouch failure, as nothing can passivate or halt the destruction of the aluminum layer once it's begun. One of the key functions of the aluminum barrier is serving as a non-permeable humidity diffusion barrier. Why do you care about keeping humidity out of your electrolyte? Because on contact it decomposes into HF (Hydro-Fluoric Acid).

The electrolyte in our cells is not something you want to put in your eyes or snort up your nose, but the HF risks are actually pretty remote. Our safety people have tried to make HF on purpose and found they couldn't do it. Perhaps my experience has made me cavalier, but unless literally gallons of electrolyte are nearby I don't really think about HF at all. Keep a tube of calcium chloride ointment on hand just in case. If acid forms on your skin, you can neutralize it with that. I don't think I know a single person who has ever needed to do that.

The devil is in the details with pouch cell mfg, and more companies have under-estimated it's difficulty than gave it the care and consideration it requires. There are pretty grand opportunities for methods to fail at every single step of the many step path involved in making pouch cells. Getting it right means discovering all of them and creating processes/tooling to ensure none of it can happen, which is a lot easier said than done.

Lots of devilish details in this field generally. It's tempting to look at a DIY'd EV and say, "Gee, look how easily that guy did that. What the hell's wrong with the automotive industry?" But we can't just go out and mass-produce cars with cobbled-up drivetrains and zero trunk space for all the batteries in them. Nobody can do that--Tesla's been executed brilliantly and look at how long it has taken them to get where they are and how many times they've been at the brink of destruction. The automotive industry is one of the most heavily regulated industries in the world and the engineering standards are far beyond what most laypeople and even many professional engineers from other areas realize until they actually try to build a car they can legally sell to the masses. Many have found out the hard way after it's too late, others are sure to follow, and as always most people will just remain blissfully ignorant of the effort required to bring them the things they take for granted. It is the latter group that tends to complain the loudest and longest about the engineering decisions of others.

 

[etriker]

I worked at the Strohs can plant and made beer cans.

Sometimes we were all scrapping cans.

Even the slightest mistake on the label would cause many cans to be scrapped.

They were scrapped at the plant.

It was real important to them that no one saw a strohs can with a flawed label.

When I worked at Sperry we got a bad batch of transistors and they were all over the place.

In bins on boards, all over the place.

Everyone was put on find bad transistor duty so that none of them made it outside the plant.

It is very important to destroy your mistakes like this in industry. In house.

Never let them out the door where someone else will see your mistakes.

I don't understand why A123 did not do that.

It is common practice in industry ?

All factories make a lot of scrap during the first year or so of startup ?

 

[wb9k]

I worked at the Strohs can plant and made beer cans.

Sometimes we were all scrapping cans.

Even the slightest mistake on the label would cause many cans to be scrapped.

They were scrapped at the plant.

It was real important to them that no one saw a strohs can with a flawed label.

When I worked at Sperry we got a bad batch of transistors and they were all over the place.

In bins on boards, all over the place.

Everyone was put on find bad transistor duty so that none of them made it outside the plant.

It is very important to destroy your mistakes like this in industry. In house.

Never let them out the door where someone else will see your mistakes.

I don't understand why A123 did not do that.

It is common practice in industry ?

All factories make a lot of scrap during the first year or so of startup ?

I can't really argue with any of that. I wish things had been handled differently with stricter controls, but it didn't work out that way. Like I say, many thing have changed since that time. I'll just add that Stroh's and Sperry are huge companies with well-established resources and procedures. That makes a big difference in the capability of dealing with things like big field campaigns.

 

[major]

I thought I'd throw my 2 cents into the discussion. I don't think there is a industry standard for "grade B". It appears a company (or seller) can decide what constitutes a Grade B. I find it odd that A123 considers Grade A anything above 19.5Ah on 20Ah rated cells. Why isn't the cutoff at 20Ah? That is their choice and as long as the customer or buyer is made aware, that's o.k. by me.

I also see confusion between Grade B and quality rejects. In my opinion, Grade B product can be top quality, and should be. Quality rejects should never be made available for use.

The manufacturing process lines for these cells are quite large and the process time from start to finish where the cell can be characterized takes on the order of 3 weeks from my understanding. There is a multitude of factors influencing the capacity, not just simply the number and size of the sheets stacked in the pouch. Even with tightly controlled tolerances the odds can play against you and you can end up with a large quantity of cells testing just below the capacity cutoff limit.

I don't see anything wrong with these lots of top quality Grade B cells being offered to the market for the less demanding applications at a reduced price. I mean, many of us would use cells of a few percent lower Ah if they cost considerably less than the Grade A product. And the Grade A cells may never be made available to us anyway.

 

[arkmundi]

I appreciate a good [rant] If A123 cells are so great.... as much as anyone who bought and is trying to use these cells. But this is a A123 B grade info thread initiated by wb9k and I have yet to have the most fundamental question any of us has with regards to the future of the AMP20 cells. That is the legitimate and most cost effective sourcing of these cells. It seems a win-win for A123 and the ES community if an outlet were established for B-grade cells at reduced pricing. If that has already happened with buya123batteries.com then its a simple statement to the effect. Otherwise some clarity with regards to future directions would be much appreciated.

 

[wb9k]

I know of no present legit channel for purchasing B-grade A123 20Ah pouch cells. I've been trying to open one here for a while now, but so far no success. I'll continue to try to get something going as time permits. If this interests you, I would also keep an eye on buya123's site. Maybe they'll offer them at some point, I don't know. To my knowledge, they are selling only A-grade cells right now.

 

[etriker]

I appreciate a good [rant] If A123 cells are so great.... as much as anyone who bought and is trying to use these cells. But this is a A123 B grade info thread initiated by wb9k and I have yet to have the most fundamental question any of us has with regards to the future of the AMP20 cells. That is the legitimate and most cost effective sourcing of these cells. It seems a win-win for A123 and the ES community if an outlet were established for B-grade cells at reduced pricing. If that has already happened with buya123batteries.com then its a simple statement to the effect. Otherwise some clarity with regards to future directions would be much appreciated.

this is where you can buy for real deal A123.

http://www.buya123batteries.com/

A really bad ass ebike battery pack can be made with what they are selling right now.

 

[agniusm]

I wander if free shipping is exclusive to US?

 

[liveforphysics]

The bad news is, once you have the electrolyte in contact with the middle aluminum layer inside the laminated foil composing the pouch, you are just playing the waiting game until pouch failure, as nothing can passivate or halt the destruction of the aluminum layer once it's begun. One of the key functions of the aluminum barrier is serving as a non-permeable humidity diffusion barrier. Why do you care about keeping humidity out of your electrolyte? Because on contact it decomposes into HF (Hydro-Fluoric Acid).

The electrolyte in our cells is not something you want to put in your eyes or snort up your nose, but the HF risks are actually pretty remote. Our safety people have tried to make HF on purpose and found they couldn't do it. Perhaps my experience has made me cavalier, but unless literally gallons of electrolyte are nearby I don't really think about HF at all. Keep a tube of calcium chloride ointment on hand just in case. If acid forms on your skin, you can neutralize it with that. I don't think I know a single person who has ever needed to do that.

Your safety guys didn't test it very well. It's an extremely common and well known decomposition, it's even in A123's own MSDS that lists the reaction"
"Specific Hazards arising from the
Chemical:
The interaction of water or water vapor and exposed lithium
hexafluorophosphate (Li PF6) may result in the generation of hydrogen and
hydrogen fluoride (HF) gas."

The aluminum acts as the vapor barrier. I'm not concerned in the least about humans getting HF on them, it's once you've lost your inner aluminum layer in the pouch laminate material, you have no vapor barrier, you have humidity absorbing through the pouch and generating HF inside which pretty much gets to take it's choice with what it wants to react with internally.

The devil is in the details with pouch cell mfg, and more companies have under-estimated it's difficulty than gave it the care and consideration it requires. There are pretty grand opportunities for methods to fail at every single step of the many step path involved in making pouch cells. Getting it right means discovering all of them and creating processes/tooling to ensure none of it can happen, which is a lot easier said than done.

Lots of devilish details in this field generally. It's tempting to look at a DIY'd EV and say, "Gee, look how easily that guy did that. What the hell's wrong with the automotive industry?" But we can't just go out and mass-produce cars with cobbled-up drivetrains and zero trunk space for all the batteries in them. Nobody can do that--Tesla's been executed brilliantly and look at how long it has taken them to get where they are and how many times they've been at the brink of destruction. The automotive industry is one of the most heavily regulated industries in the world and the engineering standards are far beyond what most laypeople and even many professional engineers from other areas realize until they actually try to build a car they can legally sell to the masses. Many have found out the hard way after it's too late, others are sure to follow, and as always most people will just remain blissfully ignorant of the effort required to bring them the things they take for granted. It is the latter group that tends to complain the loudest and longest about the engineering decisions of others.

I am unclear how any of this is relevant towards explaining why it's OK to sell a cell where you do not know why 5% of the expected active material in a cell is missing or somehow not connected to the current collector assembly.

 

[wb9k]

Your safety guys didn't test it very well. It's an extremely common and well known decomposition, it's even in A123's own MSDS that lists the reaction"
"Specific Hazards arising from the
Chemical:
The interaction of water or water vapor and exposed lithium
hexafluorophosphate (Li PF6) may result in the generation of hydrogen and
hydrogen fluoride (HF) gas."

The aluminum acts as the vapor barrier. I'm not concerned in the least about humans getting HF on them, it's once you've lost your inner aluminum layer in the pouch laminate material, you have no vapor barrier, you have humidity absorbing through the pouch and generating HF inside which pretty much gets to take it's choice with what it wants to react with internally.

I know what the MSDS says, thank you very much. I also understand the mechanism at work here. I'm telling you, from direct personal experience with leaking field failures suffering the effects of severe electrical abuse and cell teardowns in the lab, and from the experience of several of my co-workers who have torn down hundreds of cells, that generation of HF, even in the presence of liquid water, is very rare--so rare that none of us has ever observed it. If you have any actual experience to contradict those collective observations then please, by all means, regale us.

I am unclear how any of this is relevant towards explaining why it's OK to sell a cell where you do not know why 5% of the expected active material in a cell is missing or somehow not connected to the current collector assembly.

You're twisting the intent of my words, which were not used to justify the strawman you posit here while also presuming that we "don't know" why variation occurs. Second, I feel like you're trying to goad me into saying something stupid. I've already said I'm not a cell manufacturing expert. My exposure to that corner of the company is so far somewhat limited so I'm not the right person to argue this point, pro or con, at any level of real detail. Having said that, I can tell you A grade cells (which are spec'd at a mimimum of 19.5 Ah) today run just a hair over 21 Ah with very small variation. Perhaps the spec will change...I don't know. I've also pointed out that the total inventory of B-grade cells on hand numbers in the hundreds, a very small proportion of our output and cell inventory. Maybe to you this all spells "out of control clusterf*%k", or "dishonest manufacturer", but to me it does not.

 

[liveforphysics]

I know what the MSDS says, thank you very much. I also understand the mechanism at work here. I'm telling you, from direct personal experience with leaking field failures suffering the effects of severe electrical abuse and cell teardowns in the lab, and from the experience of several of my co-workers who have torn down hundreds of cells, that generation of HF, even in the presence of liquid water, is very rare--so rare that none of us has ever observed it. If you have any actual experience to contradict those collective observations then please, by all means, regale us.

Made a video for you.

Water + LiPF6 salts, and water plus complete electrolyte (PC/EC + LiPF6 + various additives). Interesting that it required a small amount of mixing before the water became a strong acid (pH ~0). It will be interesting tomorrow to see the magnitude of glass etching from the HF. Hopefully it will be easily visible.

[youtube]ScJ8ErTsilM[/youtube]




I don't think there is a thing wrong that a factory has cells that have mistakes/issues etc. I just think it's a little spooky to not destroy them. If a cell has high self-discharge, it's going to puff. If a cell is down on design capacity in a substantial way, something (wide range of options from benign to critical) went wrong. From my perspective, that makes it an unknown and potentially hazardous commodity that IMHO seems like a bad idea to sell to people. That said, the QC from the RC cells has been so shitty lately, B-stock A123's may very well be radically safer, but I would still sure want to know what went wrong in mfg before I would be willing to put them in my own garage.

 

[mrzed]

It's a curious question, why a North American Mfg company is letting off spec out the door at all. Perhaps there is something peculiar about the secret sauce mfg method or chemistry that results in a certain percent that fail spec in a consistent way.

 

[wb9k]

Made a video for you.

Luke,

Thanks so much for taking the time to do this, I just finally got a chance to watch it. We have glove boxes at A123, but in our corner of the company they are rarely necessary and I personally have yet to use one. I do my module and cell teardowns in a ventless hood with carbon filters, which I need more for the sake of the solvent I use to break down the glue in the module I'm tearing down than for any electrolyte fumes I may release. I wear nitrile gloves and safety goggles (reading prescription) and work through the clear lid/door of the hood whenever possible.

I'm no chemist by any stretch of the imagination, but I understand some fundamentals and have working knowledge of hobby-grade pH test kits and such from when I was keeping a coral reef aquarium. (Sure miss it sometimes, but it's a big job if you do it right.) So, I'm guessing that pH kit was acid-only with 7.0 at one extreme and 0 at the other? The deep red is 7.0? Or is it the orange that is neutral?

It was a little difficult for me to follow what was changing through the sequence of pH measurements (other than the result), but from your comments and my tenuous inferences above, I'm guessing you found it took some effort to get the reaction to happen. It bears pointing out that most of the electrolyte in our cells is soaked into the active material on the electrodes. So even if you gash a cell wide open, it takes some real effort to collect enough liquid electrolyte to match the size of your sample. In a field failure, leakage is rarely bad enough for the user to ever see more than a few drops of liquid electrolyte if even that--it evaporates rather quickly.

The MSDS instructions for removing any electrolyte from your skin is to wash it off with water (!) When we put all this together, I think it's fair to say that the risk of harm by HF is pretty remote with these cells. It is indeed possible to make HF from our electrolyte and water and HF is nasty, dangerous stuff. I don't want to downplay this to the point that people don't take the possibility seriously. At the same time, it takes more electrolyte than you are likely to encounter simply working with cells (as opposed to a jar of liquid electrolyte) AND more effort than one is likely to exert. The way the risk gets stated sometimes one might think that if you get a drop or two of electrolyte on your workbench, it might react with the humidity in the air and burn a hole to China. Keep a tube of CaCl on hand, and rest easy, I say.

Hopefully you can comment on whether I'm in the ballpark with my assumptions and also on what kind of glass etching you got.

Thanks again.

 

[dnmun]

you might wanna check the vapor pressure of the flourine because it may turn to gas when exposed at atmospheric pressure.

 

[wb9k]

I also meant to ask....is that an inert environment in the glove box? If so, will that foster a different type of reaction...speed or slow it vs. what one would see in open air?

 

[liveforphysics]

I also meant to ask....is that an inert environment in the glove box? If so, will that foster a different type of reaction...speed or slow it vs. what one would see in open air?

That glove box is just zero humidity normal atmosphere.
Adding the water in there kinda defeated it's unique environment. I did it because after years of cutting open and blowing up cells for recreation and fun videos, I think my lungs and lenses of my eyes have been scared a bit, and I think HF fume emissions from various electrolyte and fluropolymer decomposition was possibly responsible.

If it's worth it to you, get your face in electrolyte all day. I did, and I wouldn't change a thing I did over because it may not have all worked out this well or been as exciting. However I have seen first hand, even in the most ghetto Chinese factories, like the $3.99 shipped replacement phone batts from China type setups where the foil cutting is done in layers with scissors, they still give the guys adding electrolyte semi-decent glove boxes or dry rooms with fume hoods and respirators.

Ive taken that as a sign I should take at least similar precautions myself when experimenting.