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LTO Battery question
(07-21-2018, 10:05 PM)completelycharged Wrote: Interesting, especially why they try and sell them as new with images that prove they are not...

Cell + FOB pricing is what I would expect, beware of the FOB shipping sting....

Questions / points would be :
1. ICAO/IATA regulations limit the State of Charge (SOC) to 30% - 2.3V reading on the cell is over 60% SOC, would any manufacturer ship new cells at >60% SOC ?
2. Internal impediance in the spec sheet they sent and the official spaec sheet is sub 1mOhm, thier reading is 1.4 and 1.33mOhms... >30% above spec for "new" cells
3. Packaging with no cell holders, nice.... 20kg of cells in a carboard box with 5mm of packing.

Point 2 is the very reason they are "recycled" - try fast charging them at 10C at a bus stop.... 400A x  1.4 mOhm = 220W heat dissipation while charging.. from one cell !!!! Put another way 24% of the charge energy is lost as heat.... (400^2 x 0.0014) / (400A x 2.3V = 920 Watts) this is the impact of IR.... and why they are recycled...

Use them in a powerwall at 5A 0.28% heat loss.. no real issue. 40A, 2.3%, 80A 4.5%. 200A 11.3%.

From the images there are a few things, which raise issues for me, so beware.

I would need a lot lot more proof before sending them $x,000 before they release the goods... no seller will put them on a boat without full payment...

I agree with the IR numbers , but disagree with " Used " with the ones that I have,
If you look at their tests , discharge rates are .2C to .5C to get AH rating.
The ones I have :

1 Do not have any ware or scratches on either side of the threads from being mounted with a nut (aluminum scratches easily )

2 Mine tested above or equal to the rating

3 However letting them sit for a month , had a few that self discharge about 20%. They have possible internal shorts.

I put those two on the beginning and end of the string of six cells , I noticed the that the end cell got a higher charge .15v
   than the four in the middle. This was the case if I charged less than 20 ah , above that was not noticeable .

My torture set is 30AH @ 18 lbs with copper buss bars rated over 1200ah, tested @ 1 year

1: Starting small diesel trucks , cars - V8's - voltage stayed stable at 2.4/cell + or - .03v without  a BMS

2: Dc welding , did get @ 100 f hot

3: UPS battery backup

In conclusion my test set is still at 30ah capacity at .5c rate from full charge.

Please excuse my grammar because I am a "Hoppie"    ( Hooked on Phonics )

PS  , I have seen pictures on how these are made , The powdered  material being used , It dosn't require much to puncture

  the separating membrane to cause a small short.
Dissagree with "used" and then say "had a few that self discharge about 20%" in a month ?

"It dosn't require much to puncture the separating membrane to cause a small short." - are you talking about pouch cells or 66160 format ?
You might want to consider the Boston Swing 5300.  Do a search here ....Thunderheart did a nice review of it.
(07-22-2018, 10:31 PM)completelycharged Wrote: Dissagree with "used" and then say "had a few that self discharge about 20%" in a month ?

"It dosn't require much to puncture the separating membrane to cause a small short." - are you talking about pouch cells or 66160 format ?
66160 cells, Shorts can be from new .They are new seconds, maybe thirds. The membrane looks like and feels like  a cheap plastic food wrap, from a kokam 60ah pouch cell I took apart. The only difference is one wound and the other is folded.

 I have a 2.5v 6-cell capacitor over-volt board on it now, It loses about 0.1 volts per 3-4 days. Before that I bought 6 QNBBM Active Battery Equalizers, thinking that I would save power, wrong. It had 0.1v per day loss, although I had every cell within
  .02 volts. The Equalizers would work better with a larger capacity system for smaller parasitic loss.

Ever since I started using it as a starter battery , the two weaker cells are not showing the big losses anymore as much.
Possibly burned out the short, but still getting @ 450 watts at .5C from a full charge.

As for knowing between a used thread and a new one ,the steel nut , causes small circular scratches when tightened  up .        It requires re-cutting the thread at @2,000 rpm to get the scratch free bright finish. I doubt that other than a repackage job to fool the consumer, to be worth it .                                                                                                                                         I have been a Machinist and owner of a shop for 41 years,   I am not here to step on anybody's toes , But all of the 18 cells
I have, they check out at rated capacity or slightly above from full charge 16.2v-6 cells at 15ah draw. I bought mine at

As for the manufacturing process of these have a big variable --- water = IR            ( My short condensed version)
 1 mix compounds with water
 2 coat the copper and the aluminum foils then dry
 3 wind with separator to form the round inside of battery
 4 Insert into the"can"
 5 then place vacuum hose into filling hole and vacuum
 6 then fill with electrolyte (doe not contain water to what I have seen )
 7 Seal and finish package
 8 Test the cell

They show the cell being put on a machine , vacuum applied ,then add electrolyte -- time a few seconds.
Even with perfect humidity control, they have people watching the assembly, An average human puts out between 600-800
BTU's of heat and moisture per hour, adding moisture to it. Being wound up tight, It will take more than a few seconds to remove the couple percent of moisture. Its too difficult to control it in assembly, The only way to control it is with more vacuum time (Like several hours ) , I learned this from installing air conditioning systems ( My Hobby ). Water is not as good as the electrolyte for less resistance

Hence "Seconds"  It is more profitable than more vacuum time. Some acceptable loss

The one's at 10-15 US might be used, I have not bought them, I paid 20.00 for the 30ah and 30.00 for the 40ah one's from
   Shenzhen OSN Power Tech Co., Ltd.
I also purchased 200+ 30AH cells from OSN for $20USD per cell. I found them good to deal with and would be inclined to say the cells are new as the cell threads still had burs from cutting and had to be cleaned before the nuts would screw on easily.

I haven't had a chance to test them yet other than a quick pick with a multimeter showing ~2.5v on a random sample of cells and attempted assembly of some prototype packs. Hoping to be finished assembly shortly for a real world test.

However today I received an Alibaba newsletter offering cells for $7.9-8.9USD

Even if they are used or seconds they would still be good value.

Interested to hear opinions on the cheaper cells.

(07-21-2018, 01:42 PM)Tim Dale Wrote: First a quick update

The initial quote I received was not to my door, it was a FOB quote, I guess their was some confusion on what I was asking them

Also after making my sample order they reduced their quoted price to $14/cell for 400 batteries

I received some of the pictures I asked for and they answered all of my questions, but now I'm a little more concerned.

When I asked about the batteries history I was told they are brand new

I asked them to clarify, saying surly this is a mistake, that these must be high quality reclaimed cells that have been tested, no?

Their reply was no, these cells are brand new. But everything I read says these will be reclaimed cells, which I'm totally fine with as long as they are tested for remaining capacity, so I don't understand their need to claim that the cells are new

If I buy these cells I'll insist upon a capacity guarantee in the contract stating that the cells will be tested upon arrival and that they guarantee every cell will still have 40Ah of capacity, if they screw me over I can get a refund from my credit card company for breach of contract

I'm really thinking about going a bit smaller, and instead of 500 batteries just using 400 for roughly 37kWh which will be around 30 kWh usable after I de-rate the pack

Total quoted cost for the batteries FOB is $6000 or $162 kWh, I still need to figure out the cost for a freight forwarder to complete the importation, I'm looking at an LTC shipment of  500 KG consisting of 27 boxes each 200*300*400 in size.

Even if this cost is $2000 my total cost per kWh will only be $216, and LTO cells should have a cycle life 10X that of NCR18650B cells, even if it's only 2X, these LTO cells will be more economical over time than 18650's and much easier to construct battery packs with

So if the cell testing goes well I'm going to go with these LTO for my Powerwall

I'll post more updates after I get the sample batteries in, but I'm really concerned with their claim that these are all brand new, I'll have to address this concern in the purchase contract

In case anyone else is interested in the supplier that I'm talking to, their info can be found here

Any recommendations on the best way to test these cells would be appreciated 

Hi Tim, how are your LTO batteries going. I have been on Alibaba web site recently and they seam to have increased the asking price considerably.
I have posted this on a different thread also, sorry if it is not OK to post it here too.
Good to know if You are buying Yinlong LTOConfused from China.

I have bought 105 pcs. of 66160 40Ah "BRAND NEW" B-grade cells from a well known Alibaba seller.
Cells arrived a few days ago.
When I opened the packages, I found 105 rewrapped cells, blue wrap without the normal "Yinlong" texts.
There was a white barcode label with serial number and capacity on the new wrap.
I took the wrap off.
Under the wrap I found a very lightly yellowish barcode label with the same numbers.
I also found clear knifemarks when somebody had cut off the original Yinlong wrap.
Almost every cell has small dents, and both the anode and cathode look used.
I have tested the IR, I have an "YR1030+" meter, since the IR is very low, I used the ZR-setting.
The IR of the 6 cells I have tested, was between 0.35 - 0.29 milliohms, OK for me.
I have this far tested the capacity of just one cell, 41Ah from full charge to 1.5V, 0.3C.

So, the IR seems to be OK, same with the Ah. (only one cell tested for capacity).

The seller still claims that these are "Brand New", writes:

"The cells we sent to you are from Yinlong Hebei .

When they finish production and stock these cells ,all cells are uncovered ,and with a bar code on a yellow tape,I will show you some videos how they stock these cells .All of these cells are brand new .

Before shipping to us ,These cells will be tested rigorously by YINLONG QC team ,and also make blue shrink PVC on the battery....
....And as you have mentioned small dents AND a clear knifemark,it is normal,
when cells are production ,will have such of these situations .

Even you buy A grade cells ,will also face the problem ,it is just apperance ,don't affect the performance of battery ,
you can test the capacity."

I wrote to the seller:
"I just do not understand why they would first attach the yellow tape barcode label on the cell, then shrinkwrap the cell, then cut off the original shrinkwrap and leave knifemarks and small dents on EVERY cell, then shrinkwrap the cell again using the wrap without Yinlong logo and fasten the new white barcode label with the same numbers as the yellowish, on the shrinkwrap.
Do You understand why anybody would do that?"

A bit funny, I have not received an answer yet
I have a couple of new Yinlong 66160H cells with the original Yinlong shrinkwrap and the much darker yellow tape barcode under that. I took off the shrinkwrap, not with a knife but another method that does not leave knifemarks. No knifemarks or dents on those cells.

No marks of use on the anode or cathode either!

I think I shall contact Yinlong directly, give them all the info I have received and ask them if they can help.

So what to do, had to buy these by transfering money directly from my bankaccount, this Alibaba seller did not accept paypal, VISA, ordering via Alibaba or Alibabas paying method?

Regards: Piglet

PS: The cells were very well packed, 18pcs in a box with formed styrofoam inserts, 6 cells in a row.  No chance of moving in the box, touching other cells or getting any dents on transport.
(06-30-2019, 07:14 AM)piglet Wrote: I have posted this on a different thread also, sorry if it is not OK to post it here too.

Yes, removed from the Marketplace as it didn't pertain to the OP/Title.

How many cells have you tested? Being that the seller didn't accept any of the standard transfers, there's probably no way to get your money back. Never ever transfer directly from bank account. Always transfer through a secured method to get the extra insurance of fraud protection. I hope 'all' your cells are actually as advertised.
Proceed with caution. Knowledge is Power! Literally! Cool 
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(06-30-2019, 12:49 PM)Korishan Wrote:
(06-30-2019, 07:14 AM)piglet Wrote: I have posted this on a different thread also, sorry if it is not OK to post it here too.

Yes, removed from the Marketplace as it didn't pertain to the OP/Title.

How many cells have you tested? Being that the seller didn't accept any of the standard transfers, there's probably no way to get your money back. Never ever transfer directly from bank account. Always transfer through a secured method to get the extra insurance of fraud protection. I hope 'all' your cells are actually as advertised.

Hello again.

Now I have tested 14 of the 105 cells.  All are used, with dents and rewrapped.

They work about as they should, IR 0.27 - 0.34 milliohms, Ah close to 40.

When charging them, some take charge much faster than some although they have almost exactly identical voltage when I started charging them in series.
The "faster" are not at the ends of the chain,but random positions.

Also I think that the "original" light yellow label with the barcode and serialnumber and Ah-marking taped on the cell itself is also a fake. 
It has the same serialnumber as the white barcode label fastened on the new wrapping.

That would maybe mean that either somebody has first copied both the barcode and the serialnumber etc. from the "original" light yellow label and printed them on the new white label before fastening it on the new wrapping. (too much work to make exact copy!!)

Or that somebody has printed a new barcode BOTH on the light yellow label and the white label at the same time, first fastened the yellow, then the wrapping and then the white label.  All the serialnumbers of different cells are very close to each other.
All that to make a used cell to look like new!

The well known Chinese Alibaba-seller claims that these come directly from Yinlong.  I can not believe that. 
Yinlong is a very big EV and battery company, they would never sell used rewrapped not well cleaned B-grade cells with knifemarks and small dents as "Brand New".

This far I could maybe have accepted the cells, if they all work as they should, and if they were sold as used, rewrapped and NOT as "Brand New" B-grade cells.

Right now I know why the seller did not accept any  for me secure payments!  Stupid of me to buy.
By the way, the same seller has sold lots of cells to Australia too.

/ Piglet
The clean 'new' wrappers are applied to heat stressed cells (i.e. the plastic has been distorted) so they don't appear to be percieved as damaged.

Dents are obvious handling damage, no cells should have impact marks. The dents can cause accelerated locallised deteriaration due to additional compression pressure on the wrapped layers. This could show up as say a capacity loss of a few Ah, but the remaining lower layers could still be ok.

Re-wrapping is one typical the case for all the YinLong 'used' cells that are on the market becasue I have never seen a batch of true 'new' cells being sold by anyone. Yinlong will not sell them to small 3rd parties and OSN are one of the few 'large' (1,000's of cells) reasonable companies in China that seems to deal in them. Easiest way to identify what is being sold is to ask the seller to show the original wrapper labelling, serial numbers and internal resistance. H cells (40Ah) are the only cells in production so any 30Ah and 35Ah (F), whatever the claims, are old as far as I have discovered to date. Simple one on the wrappers is there is typically a year shown, which can correspond to the manufacture year/batch run.

Cells that have not been heat stressed and still have the original wrapper may have higher than specified internal resistance (some advertisers on Ali actually show out of spec readings claiming they are new, lol.) but the cells may still have close to or above the stated Ah capacity, albeit at a lower C rate.

For testing of the used cells, if you try much above 1C then the IR will play into what capacity the cells are and show a reduced 'capacity' (dissipated as heat) but if your using them well below 1C then the capacity and cycle life may still turn out to be in the many, many thousands of cycles and years calendar life.

Trying to use the used cells for rapid charge/discharge (say 5C or higher, depends on the IR) expect to have a lot of heat and an accelerated increase in IR due to thermal degredation.

As for testing, try a slow charge/discharge test at 1C or lower to work out the useable Wh of energy per cell. The voltage profile for the cells also differs depending on IR, age and cycle life.

Doing a quick search for cell images (interesting to see how many times my own images appear from different sites....) the vast majority align the cells to omit the date as it is on the other side to the 66160 / 40Ah label mark.

Basically, if buying cells, ask for images before payment and ask for an image that can't be photoshoped or copied from another site, i.e. ask for an image of say serials or your name on a card in the image or an IR test of a cell that they have shown you (matched by or showing the serial number). Then at least you know what visually is going to turn up. Then the bank payment is still a fingers crossed moment because shipping the cells out of China is typically done without the correct full documentation (hazard class documents) and you could end up with issues because a lot of ports will not handle them if they know what they are and the exporter typically can't provide the requried documents or does not so as to try and get cheaper shipment.

That was my experience on a 450 cell order.

When you say "some take charge much faster than some" what are you actually meaning, do you have a specifi example with figures ?

Some of the cells on the market are from the bus/vehicle fleet where the cells have ended up with a high internal resistance and then prevent fast charging due to excessive heat limiting the charge rate (thermal charge limiting). Once out of spec and no longer able to fast charge the impact for a bus route could be that for the shceduled stops the vehicle is no longer able to take onboard the required energy and then needs to 'slow down' on the route to take onboard enough charge or taken out of service more frequently. That is my conclusion so far based on my battery religion (belief, lol.). I believe, I truly

The IR of the cells you have would seem to indicate they are recovery cells for a fire/short circuit incident where the cells have not been cycled much, just exposed to an unknown heating level and carelsss handling after that or just bad handling that cut the outer wrapper which then needed replacement as the wrapper is effectively an insulation layer of one of the cell conductors. The quoted IR figures are seemingly below spec, although is your IR at a nominal few mA or 10C ?
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......

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