Cheap Chinese LiFePo4?

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Peter

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May 27, 2021, 2:25:51 PM5/27/21
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Hello guys,

does someone have some experience with these cheap Chinese LiFePo4 prismatic cells?
H3efb29e8c6d34b20af33136aeb60245aV.jpg


My mind is blown with the price which is around $128 per kWh including shipping to EU (and even without import taxes..).
Most buyers seems to be happy with the purchase, only very few report bad capacity and strange condition of cells.
I am considering 24 pieces for 23.8 kWh pack for my camper.
What do you think about such a purchase?


John Gibson

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May 28, 2021, 8:54:53 AM5/28/21
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I have made 3 different buys to test a few out...mixed bag on results.  However what ever you do make sure you get grade A cells.  Others are junk.  Also check out this YouTube channel where he does a bunch of testing on various cells:   (165) DIY Solar Power with Will Prowse - YouTube

Peter

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May 28, 2021, 6:54:57 PM5/28/21
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Hello John,
thank you for your recommendation of Will Prowse channel. I like that guy and already seen lots of his content.
Actually he tested same type of cells from the same seller on Aliexpress. And his cells were good.
I have do it. Just ordered 24x 310Ah LiFePo4 for $3051 (23,8 kWh). Wish me luck! :-)

Dne pátek 28. května 2021 v 14:54:53 UTC+2 uživatel john...@gmail.com napsal:

Dave McCampbell

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Jun 1, 2021, 12:20:42 AM6/1/21
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Peter.  The price of about $115US for the 280 ahr cells is right in the middle of where most sellers of these prismatic cells are.  I have seen ungraded similar capacity cells as low as about $75US and Grade A with 5 year warrantee up to about $150US.  How can you be sure these are grade A and is there a warrantee?  EVE and Lishen Grade A cells are mostly well regarded by the UTube testers at a price point near these.  Both are big Chinese companies.  Google for more testing videos.  Good shopping!

Jhon

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Jun 1, 2021, 10:25:54 AM6/1/21
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Hello Peter,

I am a bit late to answer, but after reading a lot on Will Prowse's forum. I ended up buying my cells from Shenshen Basen https://basen.en.alibaba.com/  They are a little cheaper than your vendor.  On my first order of 8 280Ah cells, one of the boxes was dropped and one of the cells was damaged despite being well packaged.  The cells look good, no bloating etc and the pack worked out fine at first, but after a couple of weeks, the cell started to drop in voltage a lot faster then the others.  After going back and forth with the vendor for a few weeks, they send a replacement, which should arrive in a few weeks I hope.  Right now I am only getting 50% of the capacity because of that single cell.   They seem to be one of the better vendors on Alibaba, although still not quite as good as what you would expect from a European store.  Shipping takes about 2 months to Canada.  I will be interested to see your experience with this vendor.

On the boating forums, they seem to recommend smaller cells, 100Ah max because the bigger ones 280Ah might sustain internal mechanical failures with the constant bouncing.  However, you will have to do some more research on that as I can't verify that claim, but you might consider some form of cushioning.

As for the SBMS0 and DSSR20's, I chose those because they produce almost no heat, heat is wasted energy most of the time and that heat has to be moved using even more energy.  The second part is the SBMS0 uses a signal to switch of the inverter charger, in my case a Victron Multiplus as I want to be able to use shore power/small generator to charge my battery.

All in all it has been a steep learning curve.  The short circuit current these cells are able to produce are frighting.  Be REALLY careful!!! Insulate your tools and cover the terminals when you do the install and use circuit breakers.

As for balancing it took me forever, wire them in parallel first for a day or so, then wire them in series, let the solar charge the battery and trust that the BMS0 (properly wired and configured for LiFePo4) cut of the charge.  After that, assuming they are not too far out of balance, (I do not know the exact figures, but you do not want high currents) wire them back in parallel and top balance using a bench top power supply.  A better option might be the EBC-A20 or if you don't want rewire from parallel to series twice  it's bigger brother, both available on Aliexpress.   After top balancing install the batteries in series (again) and do a partial discharge to 80% of capacity.  Top balancing takes patience and relying on the equipment to turn off when it is supposed to, helps.

Dacian Todea

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Jun 1, 2021, 1:00:54 PM6/1/21
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I made an order from this same seller in my case the 240Ah cells but so far seller did not contacted me. I usually expect questions as my address is a PO Box and they do not like that but will see.
If they ship I will let you know what the quality is. I prefer the 240Ah cells as they have the laser welded bolt instead of drilling in to connectors.  I also seen that the 310Ah cells have laser welded aluminium cylinders so maybe they did not drilled in to connectors still the short aluminium tap is easier to strip if not careful.
The busbars provided are fairly useless so I will need to find or build something else. 


On Thursday, May 27, 2021 at 12:25:51 PM UTC-6 Peter wrote:

Peter

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Jun 1, 2021, 2:31:04 PM6/1/21
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Guys, thank you for your responses!

JHon,

I was in direct contact with Basen, for 24x 310Ah LiFePo4 they wanted $5614 including shipping and taxes to Czech rep.
These sellers on Aliexpress offered me best price $3051 - $3100:


I have picked LiitokalaVariCoreFlagship Store for these reasons: almost best price, fast English communication, Will Prowse tested theirs 280 Ah cells and they look fine. I will let you guys here know if this pick was lucky.

Bouncing problem.
It came to my mind few times but in the end I was just going to risk it without cushioning.
Can you imagine cushioning real solution in the van of 135 kg block of cells? I will probably compress them just to have one single piece. But I guess primarily I need to mount it securely to the van. Would someone have a suggestion how to securely cushion such battery?

Yes, the short circuit current keeps also bothering me. Impedance of single cell is according to datasheet only 0.18 mΩ. That is crazy.
What is short circuit current of 8S3P pack? Over million amps? If I will be even able to get a fuse which will be able to break such current..
Does even exist circuit breakers what can stop such current?
I have sent a question to Basen what would be short circuit current of 8S3P battery, I am looking forward to their reply.


Dacian,

why do you think their bus bars are useless? I imagine they are quite thin.. but I will take only 150A, they could handle that. Maybe their lower quality bus bars would help me to lower short circuit current so fuses or breakers could be more successful. Does it make any sense?
Dne úterý 1. června 2021 v 19:00:54 UTC+2 uživatel electr...@gmail.com napsal:

Dacian Todea

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Jun 1, 2021, 8:19:27 PM6/1/21
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Peter,

If cells are 0.18mOhm then 3 cells in parallel will ideally be 0.06mOhm but there is also some contact resistance and busbar resistance then 8 cells in series will be 0.06mOhm x 8 = 0.48mOhm but when you add the connectors contact resistance and busbars you will be lucky to have 1mOhm total battery resistance then there are the cables that will add some resistance.
So absolute worse case short on the battery terminals will be 26V / 0.001Ohm = 26kA so not as extreme as you think and there are many breakers capable of much more than that. The typical small breakers are usually capable of 10kA and those are usually connected to thinner wires that add resistance thus short circuit current will be much lower than at the battery terminals.

The busbars are thick enough but they are not flexible. They should be made from multiple much thinner sheets of copper that have a bend in the middle to allow for thermal expansion/contraction and also cell expansion contraction with SOC
Here is a photo from someone using the SBMS0 that has proper busbars but just  in one direction he still uses the bad busbars that comes with the cells even if is a bit less critical in that direction.

 4s2p-lifepo4-2.jpg




Peter

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Jun 2, 2021, 9:55:07 AM6/2/21
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Dacian,

thank you very much for short circuit current estimation, now its all clear to me, nice.

Battery cell busbars..
Is thermal expansion of busbars a problem?
I guess if busbars get hot, they are undersized and should be bigger.

Is SOC cell expansion a problem?
With compression of cells there should be no stress on busbars and battery terminals.
Without compression I guess it should be fine to define 2mm gap between the cells. Also it seams these cells are already prepared for some SOC expansion:
cells.png

Those bended multi copper or braided busbars look awesome but they are also expensive as hell.
I tried to look for local thin copper sheet if I could create my own multi copper bended busbars but it seems its not realistic option.

I will probably compress the cells because in the van I will have only one block to mount to the floor.
Then I was going to use original busbars and missing pieces I would do from 18x1 mm copper pipe.
Do you think thats acceptable solution?



Dne středa 2. června 2021 v 2:19:27 UTC+2 uživatel electr...@gmail.com napsal:

Robert Slackware

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Jun 2, 2021, 11:01:23 AM6/2/21
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lord mounts, and may seem strange, but the shocks on a small motorcycle or mini bike should be just about right for that weight.  Maybe look at the mono shocks to keep space down.
Woke up with one of those kid science shows on tv.  Rare earth magnets, and let them "float" on a magnetic cushion?  If nothing else would make a neat experiment on effects of magnetic fields next to a high amp wire.  Get an extra 0.002 amps when the van is a rockin?  I swear officer, we were just charging the batteries......

Dacian Todea

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Jun 2, 2021, 12:47:33 PM6/2/21
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Peter,

You will normally have some compliant pads between the cells and those will deal with small bumps/uniformities but those two side bumps shown in that video will be reduced to almost nothing when cells will be compressed.
Any temperature difference even just +10C will produce expansion/contraction and not all materials will contract and expand at the same rate. You have copper, aluminium and steel all with different expansion coefficients.
Of course that expansion/contraction will be small and not visible with the naked eye but those cycles over time will degrade the connection point with will create more heat and so making things even worse.
You will probably compress the cells with some long steel screws and those will of course also be affected by thermal expansion/contraction.
Sellers should provide proper busbars with the cells but they just try to reduce cost. Below is my old GBS battery with the included busbars that are properly done (there are 4 thin silver plated aluminium busbars on each connection and they have a bend to help absorb any movement). And each group of 4 cells already have compression plates with steel straps installed from factory.

P1200263.JPG
 

Peter

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Aug 5, 2021, 5:47:18 AM8/5/21
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Hello guys,

my 24 LFP cells have arrived, delivery time by train to EU: 63 days.
Brand and model: VariCore LiFePo4 310Ah.
Ordered from Aliexpress shop "LiitokalaVariCoreFlagship Store": https://www.aliexpress.com/item/1005002310107408.html

Physically they seem to be in perfect shape, no visible damage, clean .
24 pieces, packed in groups of 4.
Voltages at arrival: 1x 3.25, 2x 3.27,  7x 3.28, 11x 3.29, 3x 3.30.
Weight of cells: 5250g - 5410g.
qr.jpgterminal.jpg
QR code only gives link to http://www.varicore.cn/ dummy page.
These cells are not even mentioned here.


Unfortunately from first results they seem to have lower capacity.
My testing methodology and equipment:
1. Charge to 3.6V by multiple different CC power sources (together max 0.2C). Topping to 3.6V only by SkyRC Imax B6 V2 charger, absorption till charging drops to 0.1A. (Charging voltage according to datasheet is 3.65V.) 
2. CC discharge with Atorch DL24 at 18A (0.06C) - cut off voltage 2.5V.
I have verified starting and ending voltages by Fluke multimeter and I have verified 18A discharge rate by UNI-T UT210E clamp multimeter.

So far I have tested 2 cells from first box, results are only 236Ah and 234Ah (around 76% of declared 310Ah):

20210804_082038.jpg20210804_075641.jpg20210805_023919.jpg

Yesterday I have ordered dedicated lithium battery tester EBC-A20 (https://www.aliexpress.com/item/1005002835760210.html) to have graphs and second measurement, I hope it will arrive soon.

Do you guys have any suggestions to testing methodology?
Any special suggestion how to fill dispute on Aliexpress? (I still did not confirm I have received cells so I guess I have around 20 days for testing.)
I suppose I send them table with all measured cells, photograph of full charge + photograph of testing result like above + measuring methodology and equipment I have mentioned here.
I will try to add video timelapse of discharing one cell.

Any thoughts or suggestions?
Thank you.





Dne středa 2. června 2021 v 18:47:33 UTC+2 uživatel electr...@gmail.com napsal:

Dacian Todea

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Aug 5, 2021, 1:25:25 PM8/5/21
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Peter,

Thanks for posting the details.  I also ordered 230Ah cells form same seller tho they where advertised as 240Ah cells. Those where EVE cells but that was not mentioned anywhere. In any case due to may PO box type address the seller did not ship and just a few days ago I got my money back and ordered different cells from a different seller hopefully they will be shipped this time.

That tester that you have can be way out of spec it may be best to use something else for example SBMS0 will be way more accurate but you need at least 4 cells so is more energy required.
Based on weight those are 272Ah (280Ah) cells so it is somewhere between your measurement and the claimed capacity.



John Emmert

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Aug 5, 2021, 4:57:02 PM8/5/21
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The only vendor that I have received genuine grade A cells from (and you do pay grade A prices):


They are matched by EVE in batches of up to 16, and come with the EVE test reports. 

Bjorn Teani

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Aug 7, 2021, 9:15:46 AM8/7/21
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Well, I bought "the same" 310Ah cells but from "GlobalPower Co., LT Store" (I followed your lead, Peter :D)

They are in transit and I'll report here when I have them.

Frank S

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Aug 9, 2021, 1:36:46 PM8/9/21
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Hi,
I also ordered 24 310Ah cells but on Alibaba - from Shenzhen Beiersite E-Business Limited in middle of March 21. Got cells delivered in Juni.
Cells were thoroughly packed in foamed boxes to 4 cells. On checking the cells I found one cell sitting at 2.99V, all other cells were on 3.29V. One cell was damaged on one corner as it was dropped.
I filed a dispute after trying to negotiate with the seller. He claimed that all cells were tested before shipping, so it muss happened during transport...
In the dispute the seller suggested that he will send new cells if I agree and close the dispute. I did and was looking forward to get new cells. Instead of shipping new cells the seller refunded those two cells straight away! I was not happy and tried to escalate this face solution of the seller to Alibaba in opening another dispute - but Alibaba didn't reply. My second dispute was not even filed! The seller replied that he had refunded the cells and he would have send new cells only if I had placed another order!
Meanwhile I assembled the battery - same as Peter 3P8S and it turned out, that the 2.99V cell is playing crazy within a cluster of 3 cells.
On charging this cluster reached OVD first and drops fast in voltage after a short time without any loads on the battery!
Prior, I had all cells assembled to a 24V system and charged with my victron MP 2 with SBMS0 as controller. Then I re-arranged cells in parallel and toped all up to 3.6V, left its for 24h in parallel and reconnected the cells in 3P8S configuration.
Observing the SOC/voltage of the battery/cells I'm pretty sure that this block will not deliver the performance intended/ordered/expected.
Finally, I ended up ordering additional 4 cells from the same seller to get same brand of cells to swap cells which are not performing.
I'm very unhappy with this deal - next time I will consider buying Winston cells instead of this Chinese crap.
I posted this story already on FB and was blamed for can going for the cheapest cells - it is well known that these cells are not A-Grad...offer was for A-Grade cells...
To justify my purchase, I was not going for the cheapest cells on Ali, but for the most comprehensive deal. No tax no duties would come on top, only shipping - that was my criteria.
What I have learned from this deal - next time - if ever! - I will order more cells than needed. An additional set of four cells should? be enough 
 to assemble the desired system. After completion of the project I will sell these surplus cells for a reduced rate - unveiling the background/history. So I could reduce my loss...
Peter - I attached some pictures of my battery box, made out of 24mm plywood. Compression is achieved/maintained with stainless steel threaded rod. With a router I cut a 9mm groove in the plywood and inserted a sheet of 9mm plywood where cells are resting on. The bottom set of rods is right underneath this floor inserted to carry the weight of the cells. To secure the box on the floor I screwed  aluminium angle profil into the wooden floor in the distance of the box, inserted the box in between and drilled holes through the box walls. The floor where the cells rest on is prox. 50mm from the bottom. From the inside I put metal inserts in to be able to fasten the box to the angle profil...Cells I wrapped in insulation paper - Dupont Nomex paper, pricy, but I wanna to be safe... 
Box is approx. 1400x265 footprint, hight is 360mm...calculate 50mm floor, floor, cell hight plus an additional 30 to 50mm for bars, cables and rods.
As it was mentioned earlier, delivered busbars are somehow useless. Holes only fit if one puts cell flat next to each other, won't fit if in series. I made busbars from copper flat material, 20x3mm equals 60mm2. I'm also not drawing more then 150A with my MP2 24/3000/70.
I'm not happy with the busbars as its are rigid allowing no length compensation on temperature differences.
With this amount of capacity - once updated with new cells! - I'm hoping to cycle the battery only within 30 to 80% max - though giving hopefully a long lifetime...
My application is also RV. A word to the fuse - I fitted a T-class fuse from Blue Systems, 400A. It'll safely disconnect the battery from the RV in worst case. AC I'll get from my victron MP2 and hopefully disconnects by order of SBMS0 and DC loads are cut off via a victron BP. Since I only run small appliances like LED light, Truma gas heater and fridge, a 65A BP will do the job.
A suggestion to make life with SBMS0 easier - I bought cat5 lead and cut off one plug, jammed the individual cables into the green connector and mounted a socket for RS45  behind the wall and connected the individual cables to inverter, shunt, DSSR20 and BP. With this setup I only need to unplug the cable from the socket! Easy...
Frank
  IMG_20210706_123851.jpg



IMG_20210809_163047.jpg
IMG_20210809_190722.jpg
I used EBC-A20 to top up cluster 7...

Frank S

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Aug 9, 2021, 1:55:18 PM8/9/21
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some more pictures from the box
IMG_20210809_190432_01.jpg
IMG_20210809_190510_01.jpg
IMG_20210809_190453_01.jpg
I hope that'll do...
If more - send me PM
Frank

Frank S

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Aug 9, 2021, 2:04:28 PM8/9/21
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Testing 24 cells with "DIY" equipment - even with EBC will take a long time! Consider 5Ah charging and 20A discharging - with 310AH cells?!
I skipped that...grouping cells should be done according capacity right? Since I don't know each individual capacity I grouped the cells according internal resistance. Cells vary between 0.19 and 0.26mOhm.
Does that sound visible - grouping according internal resistance? Or is that useless as rigid busbars...?

Frank 

Dacian Todea

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Aug 10, 2021, 6:36:35 PM8/10/21
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Frank,

You have two SBMS0 photos one showing cell 7 as 3.355 and the other 3.508V. What is the background ? What photo was made first and how long did the cell 7 took to drop to that lower level ? Or was that 3.355V just a temporary reading of a few seconds exactly when you took the photo then jumped back to 3.508V ? 

You mentioned a 400A fuse ? Where is that placed ?   You should have no fuse, breakers or switches between the battery+ and current shunts.  The solid busbars are a big problem especially in high vibration environment like an RV .

Lee Tim

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Aug 14, 2021, 8:01:16 AM8/14/21
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@Peter,
This 310Ah cell will likely end up with 280Ah-290Ah capacity.
I've seen other people's experiences in other forum threads.


For your reference. Of course the final result is based on your test.

@Dacian,
Your mention of the weight of this 310Ah cell reminded me that this could be another piece of evidence. Because the weight of the A gauge EVE 3.2V 280Ah cell I sell is 5.3kg (+-0.3). This would be a quick judgment of the battery capacity.

@Frank,
Your system looks great. I'm sorry to hear about your unpleasant experience with other Chinese sellers. I'm a Chinese seller, but I only sell A-grade EVE 3.2V 280Ah cells, model LF280N. If you need this cell next time, please contact me.


I'd like to continue your conversation and explain the price of A-grade cells. Because I found that most buyers are not very knowledgeable about the price of the cells, after all, you can see all kinds of prices on Alibaba.

In fact, the three brands that we all know, EVE, LISHEN, CATL, are relatively close in price for the same capacity of the cells. So I take EVE 3.2V 280Ah as an example, the current price of this cell without shipping costs, A gauge should be $115-$125. The reason for this range is that each seller has different operating costs and profit targets. Some sellers may lower the price of the cells to attract customers, but you will find that they raise the shipping costs. The final price is still relatively close.

About six months ago, the price of A gauge was $90-$100, but due to rising material prices and a big shortage in April-May, the price of cells (including the factory price) went into an upward spiral until today. The price has gone up about 20-30%. Material prices haven't started to come down yet, so cell prices will probably stay at this level for a while.

So for a 280Ah, it's hard to get a Class A product under $110 today. If you see a price like $9x, make sure you look at it with shipping costs, if the shipping costs are normal or lower, then it's not an A-grade cell.

I'm not familar with other small brands of cells, so I can't explain their prices. I was curious about their prices and quality. So I've been tracking about their situation in use.

Tim Lee

Dacian Todea

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Aug 14, 2021, 12:33:41 PM8/14/21
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Tim,

Why are so many B grade cells? Where are this coming from ? Are they production quality rejects ? Or are they used cells from some applications like electric buses or something similar? 

Lee Tim

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Aug 14, 2021, 4:03:12 PM8/14/21
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Hi Dacian,

The definition of B grade products is actually very simple from the factory end, one or more of the tests do not meet the requirements of the product but close to the test standard is B grade products. 

Some B-grade products just can not meet the requirements of the appearance, such as pits, scratches, terminal size deviation, but this does not affect the function, completely can be used as A-grade products.

Some B-grade products are not in line with the standard parameters, such as capacity slightly lower than the standard, or resistance slightly higher than the spec. These products can be used in the field of parameters and consistency is not very high requirements.

So B-grade is not quality reject. It is accepted by lower standards. It is not used, it's brand new.

In actual production, there are not a lot of B-grade products produced. So why does it seem like there are a lot of B-grade products? Since enterprise level customers generally only use A-grade products, B-grade products are more often used in the bulk market. There are some areas where the standards are not as strict, then purchasing B-grade products can ensure functionality and cost savings.

Another reason may be unknown to buyers yet, sellers selling A-grade products are less profitable (based on market competition and the price transparency of A-grade products) and prefer to sell B-grade products for high profits(bad money drives out good).

In fact, for individual users, it is the best value for money to buy B-grade battery cells. But it may also be more expensive. Because the definition of B-grade in the market is complex, not all B-grade we see is "real" B-grade (as the define by factory side). The price of the real B-grade is not as low as we think, as the performance is close to A-grade, so the price of B-grade is always not far from the price of A-grade. This complexity is the root of the variety of prices we see today, used/refurbished/fake/old stock, etc. are also said by some sellers to be B-grade products.

If can find a seller which supply real B-grade, it is a good way to save money. But for most buyers only buy 1 or 2 times cells in the 3-5 years, it is not easy.

Dacian Todea

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Aug 14, 2021, 4:35:37 PM8/14/21
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Thanks Tim,

That is exactly as I imagined.  I will say that as long as cells are not punctured or have internal short both of witch should be immediately visible the lower capacity or higher internal impedance should not be a problem for any user.
My A123 systems 20Ah cells where likely the same type of grade B and those 8 cells setup as 8s10p power my house for the past 4 years with absolutely no problems and can continue to do so for at least another 10 years.
What I will consider a bad seller will be someone that sells punctured cells or cells that where returned as they where abused by someone not using a BMS and doing and over charge or over discharge.

Ian Sfakianos

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Aug 14, 2021, 9:55:43 PM8/14/21
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Bit of a thread-jack but since Dacian mentioned the grounding straps I thought I'd chime in. Galco.com has hundreds of ground straps available in different sizes and ampacities. They're generally a lot cheaper than the EV place you mentioned Dacian. Here's an example:

I also noticed that several items like buss bars and battery lugs at the EV place are not exactly competitively priced. I've been using Waytekwire for the stuff I've needed. They do sell the Blue Sea brand and that's expensive everywhere, but the Eaton Bussman stuff is decent quality and less expensive. They have a very versatile range of ANL fuse holders that can be used singly or snapped together in any number for making power distribution blocks or just bussbars. 

And I searched far and wide for a range of battery buss bars before I ended up making my own. And clearly I'm not alone in this. If anyone knows of a vendor for the multi-layer, curved ones, please post it.

Plamen

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Aug 15, 2021, 4:32:35 AM8/15/21
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https://shop.gwl.eu/LiFePO4-accessories/?cur=1       Bought mines from here, just tinned them.

Dacian Todea

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Aug 15, 2021, 1:27:35 PM8/15/21
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Ian,

Thanks for the link that should be very useful to others. I just made a quick google search and added the link to EV place as that is what the google results showed and it was mostly to give an example of what I'm talking about.
The problem with the one you linked is the 10.5mm hole as most people use the blue 280Ah cells from China and those have 6mm screw so this one will be better https://www.galco.com/buy/ERICO/563540 but it seems very few are available in stock.


Plamen,

Those are solid not as good especially if they are thick as some of them look like there.

Plamen

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Aug 15, 2021, 2:31:58 PM8/15/21
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Each is made of 5 plates and the black shrink tube in the middle holds them together. I just tin them.20200210_160255.jpg

Dacian Todea

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Aug 15, 2021, 2:39:25 PM8/15/21
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Those seems to be OK with 5 thin plates and the shape that allows small amounts of movement.

Ian Sfakianos

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Aug 15, 2021, 11:17:05 PM8/15/21
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Thanks Plamen. I should have said I'm looking for vendor for battery connectors in North America. I'm sure I haven't exhausted all possibilities but the searches I've done have not kicked anything worthwhile back. It seems that making your own is how it has to be, for now at least. BTW that's very shiny tin plating! Nicely done. 

Peter

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Aug 18, 2021, 1:38:12 PM8/18/21
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Tim Lee, please, read this one..

Hi guys, thank you for your inputs.
I am still testing my cells and I will share the results later, it looks like my cells are around 240 Ah capacity.
I have found some interesting stuff.. under improperly attached top insulation I have found original scratched QR codes:

1.jpg

On most of the cells they are unreadable.
But on some cells there is very useful info:

3.jpg

Especially original caparity of the cell: 736 Wh
7.jpg

736 Wh at 3.2V means 736 / 3.2 = 230 Ah.
On this cell I measured real capacity 245 Ah.

I also managed to reconstruct that original QR code:
4.jpg

It says number 08ICB29001182A9A60100128.
From the little I have found first 3 letters "08I" could be manufacturer and "9A6" could be manufacture date. But I cannot decode these values..
Can anyone decode that?
Tim, would you know?

Dne pondělí 16. srpna 2021 v 5:17:05 UTC+2 uživatel sfakia...@gmail.com napsal:

Kurt Marasco

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Aug 18, 2021, 5:45:27 PM8/18/21
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The Galco "ERICO Ground Straps, MBJ Series", https://www.galco.com/buy/ERICO/563540, indicate 120amp max. Is that sufficient when using a Victron 24v 3000w inverter? Victron recommends a 300 amp fuse.
Thanks.

Lee Tim

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Aug 19, 2021, 5:01:03 AM8/19/21
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Hi Peter,

You are right, it has only 240Ah capacity (I thought it could be up to 280Ah according other thread I saw).
 
The original QR code indicates that this is a 3.2V 230Ah battery cell from REPT. This can be read from the markings (REPT 3.2V 736Wh). 

REPT stands for REPT Energy Co., Ltd. which is a Chinese battery company that develops and manufactures power LFP and ternary lithium batteries. 

Most people may not know about this company, so I'll explain a little more:

Although it is a relatively new company, founded in 2017, the founding team has been developing LFP batteries since 2008). The company is growing fast. It mainly supplies power cells to electric vehicle companies. So it is not common in the wholesale market.

Last year (2020) it entered for the first time the market share ranking of EV power batteries (Chinese market) and was ranked 8th. EVE ranked seventh and LISHEN ninth. (Top 10 list: 1, CATL; 2, BYD; 3, LG; 4, CALB; 5, Gotion; 6, Panasonic; 7, EVE; 8, REPT; 9, Lishen; 10, Farasis)

It ranks fourth and EVE ranks fifth in the market share of electric vehicle LFP power batteries (China market). (Top 10 list: 1, CATL; 2, BYD; 3, Gotion; 4, REPT; 5, EVE; 6, Lishen; 7, GreatPower; 8, Wanxiang123(A123); 9, CALB, 9, Lishen, 10, Anchi)

I don't know the serial number coding rules of REPT. 
From the length of the serial number "08ICB29001182A9A60100128", it looks a bit like EVE's serial number rules. According to EVE's coding rules as you said 08I is the manufacturer, 9A6 is the date, representing the product is produced on October 6, 2019.

But since we already know it is a REPT 230Ah LFP battery cell. The interpretation of the serial number is not important.

So there are at least two conclusions that can be drawn now: 
1, they are fake 310Ah battery cells; 
2, the original cells are not A Grade REPT 230Ah cells.

In all rest cases, the best case that I can think is they are B grade REPT 230Ah cell. Thus at least you can still use them in future.

Peter

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Aug 19, 2021, 6:05:53 AM8/19/21
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Tim,

thank you for this amazing information! I am very glad we have you here.. :-)
Can I add some more questions?
1) Original label on my REPT cell says "736 Wh", cells have real capacities according to my measurements: 245, 249 Ah.
On some others I have found "704 Wh" with real capacities 234, 235 and 237 Ah. This number definitely corresponds to reality.
Do you think these labels on cells are target capacities or they are real measured capacities on the output of the factory?
Why do you think 736 Wh are 240 Ah cells? Calculation 736 / 3.2 gives 230 Ah.  704 / 3.2 is only 220 Ah.
Are there some "market standard" cell capacities?

2) Who is VariCore? Or "Brand Liitokala" / "Brand VariCore". I guess these are only unimportant labels of some Ali reseller, right?

3) Do you think these mine cells are new or used? You decoded the date "9A6" -> "October 6, 2019". So maybe they could be used..?

4) If I consider for example 8S3P configuration, can I use these ~230 Ah cells in parallel with legit 280 Ah cells with no trouble?

5) Quality of cells CATL, EVE, Lishen, REPT.. is kind of the same? Is it possible to say these some are slightly better than the others?
Does it really mater to try to obtain original datasheet from REPT? I have CALT and EVE datasheets and they look very similar.

6) I am preparing for the dispute on Aliexpress. I am going to submit:
- My capacity test results (all cells around 240 Ah), each cell will have 2 photograps: fully charged with IMax B6 v2 charger + fully discharged with my Atorch discharger with real capacity. I am going to also submit 3 complete video timelapses from testing (charge+ full discharge).
- Evidence of scratched labels on cells while some still show real capacity 704 Wh (230 Ah) or 736 Wh (220 Ah) - that fully corresponds to my test results.
I am going to demand probably 2/3 of my money back.
Would you have some ideas how to be more successful in Ali dispute?

THANK YOU!



Dne čtvrtek 19. srpna 2021 v 11:01:03 UTC+2 uživatel puppy...@gmail.com napsal:

Lee Tim

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Aug 19, 2021, 8:03:15 AM8/19/21
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Thanks, I'm actually curious how I joined this group ^-^

1) Original label on my REPT cell says "736 Wh", cells have real capacities according to my measurements: 245, 249 Ah.
On some others I have found "704 Wh" with real capacities 234, 235 and 237 Ah. This number definitely corresponds to reality.
Do you think these labels on cells are target capacities or they are real measured capacities on the output of the factory?
Why do you think 736 Wh are 240 Ah cells? Calculation 736 / 3.2 gives 230 Ah.  704 / 3.2 is only 220 Ah.
Are there some "market standard" cell capacities?
--------->
The mark 736Wh is a rated/standard capacity. 

It is based on Product Design/Specification. When manufacturing, the chemistry used needs to be slightly higher than what is calculated to ensure that the actual capacity of the battery produced will be at or above the rate capacity.
The 240Ah I said is based on the actual capacity your testing result, not based on the mark "736Wh".

Those mark 704Ah should be rated 220Ah cells.

There is no standard capacity here. Each manufacturer makes their own rated capacity based on product design specifications and their own manufacturing process. If a manufacturer can only ensure to achieve no less than 220Ah for the same size, then the cell will be rated as a 220Ah cell. If another manufacturer can guarantee no less than 230Ah, then the model will be labeled as 230Ah.

So you will see that each manufacturer has its own line of products. They are not all the same.

Those 704Wh cells are marked REPT? I don't think REPT has a 220Ah model, their LFP cell series are 50Ah, 100Ah, 120/135Ah, 150Ah, 205Ah, 230Ah, 280/320Ah.

2) Who is VariCore? Or "Brand Liitokala" / "Brand VariCore". I guess these are only unimportant labels of some Ali reseller, right?
---------->
I'm actually as curious as you are. Maybe its as you think. 
I was curious because the price of their cells are always incredibly low, so I tracked down some threads to find out the quality of their products at the customers side. 
In this case, what I see is that they are not real cheap. I think the price you paid actually almost can buy A grade 230Ah cell.

3) Do you think these mine cells are new or used? You decoded the date "9A6" -> "October 6, 2019". So maybe they could be used..?
----------->
Honestly I am not able to confirm the source . The rest of the cases I mentioned are as below :
1, Brand new B grade batteries in stock; (this is the best case)
2, used B grade battery;
3, not even B-grade batteries;

4) If I consider for example 8S3P configuration, can I use these ~230 Ah cells in parallel with legit 280 Ah cells with no trouble?
----------->
I am not a professional in this area. I've heard a lot of different arguments, but most people's opinion is that if there is not a big difference in capacity, and if there is a separate BMS for each, it is possible to use them in parallel. This is only for your reference.

5) Quality of cells CATL, EVE, Lishen, REPT.. is kind of the same? Is it possible to say these some are slightly better than the others?
Does it really mater to try to obtain original datasheet from REPT? I have CALT and EVE datasheets and they look very similar.
----------->
CATL,EVE,Lishen,CALB are all brands you can trust. REPT is rare in the wholesale market.

CATL was very popular before, and this year EVE has gained most of the recognition.

From the evidence so far it has been proven that the battery is REPT 3.2V 230Ah and not VariCore 3.2V 310Ah. Of course you can contact REPT to try to get the datasheet to increase the evidence. I have tried searching the internet, but no luck.

6) I am preparing for the dispute on Aliexpress. I am going to submit:
- My capacity test results (all cells around 240 Ah), each cell will have 2 photograps: fully charged with IMax B6 v2 charger + fully discharged with my Atorch discharger with real capacity. I am going to also submit 3 complete video timelapses from testing (charge+ full discharge).
- Evidence of scratched labels on cells while some still show real capacity 704 Wh (230 Ah) or 736 Wh (220 Ah) - that fully corresponds to my test results.
I am going to demand probably 2/3 of my money back.
Would you have some ideas how to be more successful in Ali dispute?
---------->
Honestly, for this I have no way to make a pre-judgment, because it depends entirely on how alibaba will decide this matter. 

My only suggestion is to prepare sufficient information to prove that you purchased a cell labeled 310Ah, but received a cell with an actual capacity of 240A at most. And from the covered mark, the original cell is actually the REPT cell rated 230Ah.

Dacian Todea

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Aug 20, 2021, 7:18:26 PM8/20/21
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