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LTO Battery question
#31
(07-01-2019, 06:41 PM)completelycharged Wrote: 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 believe...lol.

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 ?

The seller was OSN.  They did claim that these cells were "Brand New B-grade 40Ah cells". 
Now they sent also a video, that according to them shows Yinlong rewrapping the cells. 
To me it looks more like the garage of a minor "jobber", not a very, very big actor like Yinlong.  In the beginning it also shows that the same boxes have some cells without any wrap BEFORE they got the new wrap!  I tried to upload the short video, without success.
I have measured the IR one cell at a time using my YR1030+ meter using the ZR-option without any external load.  To me the IR-values look OK.
"some take charge much faster than some" means that when I have for example charged six cells in series, all have had 2.24V initial voltage, some in the series reach 3 volts and some only 2.6-2.8V during the charge time.
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#32
Above 2.6V the voltage will start vary quite a bit as the top end of the charge curve voltage is less than 1Wh charge is a 100mV difference at only 0.5C from 2.6V (higher C charge rate will increase the difference due to higher I^R losses). Above 2.6V is pointless in my experience as it just causes issues for very very little extra storage.

Re OSN re-wrap, I'm surprised. The previous test stations only added a capacity sticker, no re-wrapping nonsense. Who thos test stations were/are I'm still yet to have 100% proof as to where and who originates them. The cells may well be BYD (Yinlong owner) but may equally be the bus companies / scrap dealers taking the busses written off and re-cycling the cells.

Oh, I know, I will take perfectly good new cells, hit them with a small hammer a couple of times, take of the pristine wrapper, re-wrap with my wrapper and they say, hey look at these new cells ? You could say WTF..... really ? Do I get a free unicorn with each cell ?

Within the video / pictures it is always the missed detail in the background that shows the true situation....... reminds me of an old cartoon, distraction, distraction, distraction, whack........ distraction, distraction, distraction, whack........ distraction, distraction, distraction, whack........ lol.

Consistency of boxes, packing type (special cell holder or whatever), previous tape on boxes (err....), stack height (compression damage), pallet type and consistency, floor covering (smooth for forklift), lighting, etc.

Which all reminds me, BYD as far as I know do not lease vehicles (albeit they may be state owned) so they would have no claim over the cells when taken out of service....
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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#33
(07-03-2019, 06:57 PM)completelycharged Wrote:
Within the video / pictures it is always the missed detail in the background that shows the true situation....... reminds me of an old cartoon, distraction, distraction, distraction, whack........ distraction, distraction, distraction, whack........ distraction, distraction, distraction, whack........ lol.

Consistency of boxes, packing type (special cell holder or whatever), previous tape on boxes (err....), stack height (compression damage), pallet type and consistency, floor covering (smooth for forklift), lighting, etc.

Which all reminds me, BYD as far as I know do not lease vehicles (albeit they may be state owned) so they would have no claim over the cells when taken out of service....

.... No free unicorns with each cell.. Good, no place for those.

Actually the dents are small, no hammermarks, could have caused when they have transported loose cells in a box. 
The boxes where the cells arrived were brand new, very well made with styrofoam inserts, 18 cells in a box 6 cells in a row. 
No new dents possible while in those.  Somebody is not telling the truth! 
The cells seem to be OK anyway.

By the way, why do I not succeed in uploading a short video from OSN?

OK, I took these three screen grabs instead.  See the cells with NO wrapping.
 

/Piglet
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#34
Oooooh... the plastic end caps, guess someone might have had a slight incident with cells placed in alternating directions...

The crates shown are after unloading from a pallet for sorting (or a small batch from another source) as they are not shipped like that in bulk. Which makes the wrapping on the naked cell box stand out. My best bet would be a relatively new 'incident' damaged salvage set of cells and where the cells did not actually suffert any internal damage they will probably be ok.

The floor does look like the same room one of my pallets was pictured in.



This is when I kindly and politely asked that they be re-packed after a WTF moment of thought. My guess they don't play tetris as much in China.
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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#35
(07-05-2019, 09:51 PM)completelycharged Wrote: My guess they don't play tetris as much in China.

Yes, the boxes are not 2/3, so when you add a new row rotated 90º 2 boxes wide = 3 boxes long and so the pallet would be perfect. Maybe they do not sell many pallets and they have optimized the box to the size of the cells and not the box to the size of the pallet.
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#36
(07-05-2019, 09:51 PM)completelycharged Wrote: Oooooh... the plastic end caps, guess someone might have had a slight incident with cells placed in alternating directions...

.....This is when I kindly and politely asked that they be re-packed after a WTF moment of thought. My guess they don't play tetris as much in China.

Yes, does not look like a very stable tower.

How many did You have in each box?  Styrofoam inserts?  
Did Your cells come from OSN, if so, who was the seller-person, mine used the name Susie Wang, might be a hairy man, who knows?

First mine were shipped by boat from Hongkong, I asked but OSN did not give the name of the ship.
Then after about one month and many messages to OSN I got an UPS Budapest Hungary tracking number.
After a few weeks when nothing happened I contacted OSN again.
The same OSN person told me that the cells are already in Finland and some unknown forwarder is right now transporting them to me!
Nothing arrived, OSN promised to tell who is this non-existent forwarder, but did not.
I contacted UPS and asked who has ordered this shipping.
I got an answer from UPS, it was some company at Budapest.
Since Hungary does not have access to the sea, I asked OSN if these might arrive by train from China to Hungary.
They said yes.
After about two weeks the UPS tracking number finally started to work, the six parcels arrived from Hungary about one week from that date.

So after all this I do not blindly believe anything OSN says.

It is a pity, most of these cells seem to be good enough.
I might buy a couple of hundred more "Brand New B-grade 40Ah cells".

Who might be a reliable seller?

/Piglet
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#37
Pallet packing must be within the outline of the base of the pallet otherwise it is either oversized or liable to a forklift driver ripping the edges off. The spaces also mean that the package moves in transit and works loose, increasing damage risk.

UPS are way, way overpriced for larger shipments..... if you want to try a commercial purchase / strategy as the saying goes, you have to go large or go home. 50 cells, shipping cost per cell is unviable, 200 cells starts to get sensible, 400 cells halved per cell (same shipping cost as 200....). Larger than 600 cells shipping starts to be a much, much smaller value per cell but overall shipment value risk starts to be alarming (high value pallet theft...) Risk vs reward.

Packed in 12's, custom inserts. Ended up on a larger 2m pallet due to combination of shipping cost (on a per m3 basis with a minimum charge) and the elimination of one pallet going on it's own journey.... and the pallet was then properly loaded and hot as high. Not ideal though.

Your listed as Finland..... or is this Finland the town, lol..

Use your own shipper, otherwise your goods will take on a magical mystery tour of the world. Ok, if your not liable for transit losses or damage, however they are never shipped with insurance due to the lack of proper documentation and export permitting (any excuse to default on an insurance claim).... separate set of isses surround that.

Larger quantities have to be ExW or FOB basis and the deciding factor is who or how you can get the export permit / route.

With your own shipper, you know exactly where they are every day, ship, dock, handler, etc. AND you have choice,

Reliable ? I have leant to never believe anything that sellers tell you, always confirm yourself by other means, even paying a local 3rd party to visually confirm if a completely untrustworthy source.

Pricing on the cells is way too high at the moment due to lack of supply, chepaer cells are as you have found out re-wraps. The cells doubled in price a few months after my shipment, which was at the time China removed a lot of the subsidies for the busses and resulted in a temporary excess.... timing may be everything on some occasions.
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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#38
(07-06-2019, 02:40 PM)completelycharged Wrote: Your listed as Finland..... or is this Finland the town, lol..
I am a Finn and live in Finland right now.

Still do not know what to do with OSN, if they would start to tell the truth, I might buy from them again.

My cells came through (or maybe from) Hungary.  Yinlong has bought a company, Icarus, that manufactures also electric buses in Hungary.
So these rewrapped cells I received maybe did not come from China at all??

/Piglet
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