A123 from China. C and avoid [SOLVED]

dnmun said:
did you ever charge these cells and try to determine what the internal resistance is and what the capacity is of the low cells versus the cells that remained fully charged?

is there a date stamp on any of them to indicate how long since they were manufactured? this knowledge is more important than just getting a refund, imo.

please let us know, and be honest if they recover fully since your thread is kinda slanted so much that maybe it would be hard to retract your comments if the cells turn out to be able to manage full capacity at the lower Rinternal.

some of us had headway cells drop to .25V and were able to recover them if they self discharged during rest from the original manufacturing date, but it is good to have this kinda baseline info about chinese cells sourced from the secondary market.
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Whats that about??? I have paid for new genuine A123 cells. I have no intention and time to go about reviving them. If i can recall correctly one of the main properties of lithium cells is low self discharge rate and these have zipp, nada they are caput.
I am making a claim on paypal next week still 100USD down on taxes.
This thread is just my bad experience so others can avoid loosing money and wasting time.
 
others do not learn anything by any of the actions you proposed. good luck collecting through paypal. not gonna happen since they can prove they delivered just what you ordered.

what i asked did not mean resurrecting dead cells. but others including myself could learn something if you could show that some cells were different, and how long it took to self discharge from the manufacturing date. so we also remain ignorant.

these are not from the manufacturer obviously, so learning how they perform from a secondary source would be useful to others, and you are the only one with the cells that anything could be learned from. imo.
 
I think its a bit early to say if i will get refund from paypal or not further more this is my personal matter.
Next thing, i have attached a document with cell voltages, individual numbers and a person can make judgement on that, i supose you missed that.
I understand what you mean, but the thing is i was looking for genuine stuff and intension is so people would stop buing from sellers who tries to trick you so that they wont have business and evetualy dissapear. I supplied all the data there was, and if there was manufacturing date i would included it dont you think?
If you buy a car you get in and drive off, you dont need to put some oil in or blow the tires. simple as that, if supplier said he will supply what i was asking for and did not, he is unreliable and everyone should avoid. I dont think you'd be happy if in my situation and it is not a question of testing etc.
 
I don't mean to sound like an asshole but it's pretty much well known that if you buy from alibaba you are taking a risk. And an even bigger risk when buying such an item as A123 cells. We all also pretty much know it's next to impossible to get these cells directly from A123 and that the majority of the cells for sale are rejects of some type. So when buying them you should go into it knowing this and be prepared for this fact. This mean, be ready to test them upon arrival. If I were you, I would put a charge to those cells and if they took it, and discharged at a good C rate, be happy I got "good" cells. Remember LiFePo4 can take a discharge like this and not necessarily be destroyed.

Heck it's actually kinda good news for the rest of us that the supplier didn't just take your money and run, and you got what apears to be decent looking cells. It would really be good for us if you would test them.
 
Seller clearly asked him to send cells back , didn't he?
Where exactely it says in his thread that it was Alibaba?
I doubt getting LiFePo cell below 2V will not have affect on longevity of cell. For sure it will have.
please, keep us informed if you got refund from Payapal.
 
Thanx for your input. I guess i knew there was risk involved. Not true that you cant get genuine A123 cells but at what price. In Germany its 60 euro per cell http://shop.lipopower.de/A123-Systems-AMP20M1HD-A-20Ah-Folienzelle
I wonder now, on that site they are marked as USA cells. Does any one know and has confirmed from A123 that they do not manufacture them in the US? It is strange because The USA cells were some what ok and Korea one dead.
Another thing, notice the packaging of the cells on German site and on my photos. The US cells have slightly different packaging, notice the separator in the middle.Korean is strait bar where US is curved.
Now i would test them for you guys but i have no means of doing so. I will get my charger in couple of weeks and will not have BMS for few months cause it is still in development. Now, maybe there is a relatively safe way to try and charge them using generic charger, say hock up 4 cells and use car battery charger for some hours? I read somewhere that you use 3 ohm resistor and multimeter to measure what, AH of the cell??
What i am saying, some of you are experienced in this business and i just dont want to risk further on my knowledge so post your tips on how to test them and i will do my best to get as much info as possible.
 
yep, i was gonna say it looked like you were not set up to test them. i did not see any way to date them either from your pics.

from my experience with paypal claims, i do think it will be hard to return them though so maybe consider investing in a single cell charger to charge them individually. there are large ones that will put out 40W and small ones of about 6-7W too, the wall warts like the volt phreak, which all seem to burn up. but you will need something to bring all the cells to the same state of charge SOC when you assemble the battery pack.

to test them like dr bass did for the other cells requires a CBA. if not, you have to build a load to discharge the cells into which allows you to change the load so the current changes, and measure the delta V manually with your meter, which is how you would evaluate the internal resistance.

all a little more than novice undertakings, but maybe something to learn on.

did not mean to diss you earlier, just was thinking it would help to know more since these are the first ones i have seen with the tabs still intact, which implies they were not rejects like the others that appeared on ebay with the tabs removed.

BOL, we can help as best we can. maybe someone else got these cells too.
 
i will see how it goes with paypal. If all good i am considering Headway route. I will lose on weight 8kg's but it looks like there is less confusion with them. I cant experiment with the cells cause by the time i will source and ship the charger my paypal claim date will expire.
 
In all honesty, if they perform, I would rather have these "damaged" cells over headways any day. You are not only going to sacrifice weight but also a butt load of C rate. Headways really should not be pushed to more than 5Cs max and 3Cs continuous.

Wile it would be nice to know the internal resistance of these cells, testing them isn't that complicated. All you really need is a volt meter that reads in amps, a set of 12 volt halogen auto lights strung together (so you can really try and pull some decent amps from the cells), and a way to charge the cells individually. First see if they will take a charge, then if they will hold a charge, then what their discharge rate is. . All pretty easy.


miro13car said:
Seller clearly asked him to send cells back , didn't he?
As mentioned before, this is a common delay tactic with a lot of these over seas vendors. They lead you along in email long enough for the paypal claim policy to run out. So don't put too much faith into that.
Where exactely it says in his thread that it was Alibaba?
My mistake, but still, it's risky buying from ANY unknown Chinese vendor.
I doubt getting LiFePo cell below 2V will not have affect on longevity of cell. For sure it will have.
Yes you are right, but when you are paying a fraction of cost compared to then again does it really matter. So instead of over 1500 cycles you only get 1000. That's still a shit load of use.
please, keep us informed if you got refund from Payapal.
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i would cycle atleast 1 cell. Ive seen many esers take their a123 to the grave by mistake and they slow charged it and they bounce back after a few cycles.
 
i was just reading the fine print on the declarations page, for the IATA regulations, and noted it says that these are certified as not being restricted from air transport because they are not rejects. i assume you have to file a similar application to ship them back air mail.

i agree these are better cells than the headways, but my headways came back from sitting idle. the lowest was .25 and a few around .5-.7 after one year so i think that is what happened with these.

in fact i wonder if they were part of a short production run done to meet a performance guideline with GM when GM was considering which source to use for their production. so these may have been manufactured as much as 18 months ago too. and got disposed of through a liquidator, and are now being sold through more discreet jobbers in china. supporting the price by limiting the amount that is entering alibaba at any one time. until they are gone. i doubt if marty could comment on it publicly either.

you gonna need a single cell charger anyway if you intend to build your own. and a load box too. and all the tools, it never ends.
 
To combine the cells together the cells have to be of same voltage all cells to be parelle or series. On such large cells it is even more important and should be cycled before being made into a pack. Plus those cells might be hard for you to connect. Still there are many single cell lifepo4 chargers at 2a for cheap. And a blub for discharge. I wouldn't start bending up those tabs and cash in your chips for some screw tops easier for you to start with. Headway has stopped making the 16ah cell I think.
 
Thanx. My brother has a charger for cylindrical lithium cells he got with hes gun flashlight. I wander if that would suit? Here is that set: http://www.ebay.com/itm/UltraFire-C...lashlights&hash=item231115dc2d#ht_5272wt_1063, it says that the charger is putting out 4.2V and 600mA. What do you think? If it does suit, for how long i should leave the cell charging?

999zip999 said:
To combine the cells together the cells have to be of same voltage all cells to be parelle or series. On such large cells it is even more important and should be cycled before being made into a pack. Plus those cells might be hard for you to connect. Still there are many single cell lifepo4 chargers at 2a for cheap. And a blub for discharge. I wouldn't start bending up those tabs and cash in your chips for some screw tops easier for you to start with. Headway has stopped making the 16ah cell I think.
Click to expand...

But if i assemble a pack with BMS (if they turned out to be ok) BMS should take care of balancing the cells to the same voltage?
I will not start playing with tabs until i have good cells. Second, i am thinking of terminating the cells like a fella from my home country on hes scooter: http://e-motion.lt/bbpress/topic/12/page/5 only 4 piles, 6 cells per pile. Dont want to get in to that on this thread, will start a project thread maybe later in winter.
This guy has made BMS for large applications: http://elektromotus.lt/en/products/bms and is in process of making BMS suitable for bikes, i would guess less expensive which i am waiting for. He said that in plans there is bluetooth and support for windows mobile and android. Fingers crossed :)
 
Could someone brake it down for me the trick with bulbs to test the cells. Should i connect say 4 cells in series and then hook up some 12V light bulbs in parallel? What then? So i have a meter connected and keep checking on the voltage as well as time?
 
An alternative for testing is buying a few metres of Nichrome wire and a ceramic termination block. You can make a short circuit with the nichrome and dunk it into a coffee mug full of water. It will boil away merrily. If you want to test at higher currents, simply increase the number of folds in the wire. It comes typically at about 13 ohms per metre, so for an individual cell you might want about 8 or 10 folds at about 10 cm length. Should give a 3 or 4 C discharge
 
if you cannot fully charge the cells do not consider any discharge of them. that would be fatal at this point.

sorry you have been mislead to believe they are dead. maybe there is someone close by who can help you. no way to know where you are since it isn't in your info.
 
biohazardman said:
My a123 M1 cells went down to .8V. Charged the pack back up and the batts are doing great just like it never happened. I'ts been a year or better with no signs of problems. I wish you luck.
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M1 cells, the genuine product, are tough-stuff.

@OP: sorry to hear about your misfortune.

In future, go to user-name cell_man for your A123 merchandise. He's honest, has great comms and is a native English speaker.

As a general rule: cheaper isn't always better. As Methods has pointed out regarding fake mosfets, why get ripped off while trying to save a few bucks per unit?
 
You got wrong information.
cell man does not have prismatic/flat A123 anymore for sale , he sold out long time ago, neither on his web site nor on NEW FOR SALE does he offer any for sale.
Mavizen is only solid place to buy A123 , because they are official A123 distributor, but they will not sell just 12 celss to hobbyst as far as I know.
 
I was told that he does have some in stock. I order a LOT form Cellman. Definitely have a go at slow charging each cell up, do not rely on a BMS to balance them up at first though as would take a week to balance that pack. Charge them all individually....buy a small RC charger so you can get good info on how much AH went back into the pack.
 
dnmun said:
if you cannot fully charge the cells do not consider any discharge of them. that would be fatal at this point.

sorry you have been mislead to believe they are dead. maybe there is someone close by who can help you. no way to know where you are since it isn't in your info.
Click to expand...
Posts: 15
Joined: Sat Apr 16, 2011 3:06 pm
Location: Lithuania, Zarasai
 
yep, i saw he added his address, but he never replied here. he doesn't have the ability to test them but maybe someone else will buy some of these cells and test them so we know how good they are. i would expect these to be some of the best pouches available in the lifepo4. maybe cell man is getting his from this source too.
 
Hi. I have to go to capital. There is someone with lab equipment to test them. I will get more info on the cells here when i have test results. Somehow i doubt that they will perform thou
 
Got some results. 4 Korean cells where tested. We have tried to charge them with lab PSU and they would not take any charge, 0 AMP's. Taht"s what i thought, kaput.
 
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