Luyuan Tech Battery Testing/Reports Info & More

[Steve_S]

This is being changed from another Posting to THIS Thread.
Some slightly more detail will be added to the 1st-3 posts are reserved for that.
This is not for Argument, Debate & the usual Petty Nattering/Bickering, Thank You.
JUST the FACTS !

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Luyuan Technologies is a Privately Family Owned & Operated Vendor.
Simple Intro:
This evolved from Amy Wan having experienced working with "Less Desirable Vendors" who were not very good and abusing buyers.
I couraged her to move forward & develop Luyuan to "Her Standards" because she always dealt with us Honourably & Respectfully even when working for "those" others. It was a Massive Challenge and I advised them on how to best start & keep a High-Level operation offering the best for everyone that dealt with them.

To be perfectly Blunt. I did all of this for them & others for Absolutely No Compensation or Reward Whatsoever!
This is also exemplified through the vast Majority of my Thousands of Posts on this Forum! All Old Timers KNOW THIS ! or Look.
WHY ?. Because I was Diagnosed with Terminal with Cancer in 2014, Given 5-7 yrs at Best, and am now in my Final Months - will not see 2023, so I got 1 Bonus (as such) year. I have ALWAYS been a Shareware, Freeway & OpenSource guy, and will be till I am planted Solid.

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Luyuan Tech :
Matched & Batched A Cells are FACTORY tested @ EVE as runs through the batches produced.
This is the TEST Report received From EVE with the full data, Translated to English where necessary for your convenience.


"OCV1" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after eliminating the "polarization" of the finished cell;

"R1" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after eliminating the "polarization" of the finished cell;

OCV3" refers to the voltage of the cell (unit: V), which is the initial voltage of the cell tested by the OCV tester after the finished cell sits some time at room temperature;

"R3" refers to the resistance of the cell (unit: mΩ), which is the internal resistance (AC internal resistance) tested by the OCV tester after the finished cell sits some time at room temperature

Amy2022-07-20 06:33
After we place an order with EVE, EVE will test and match the cells and then send them to us, also with the original test data of each cell.
Then,we will download the data to our own system. When we scan the QR code of each customer, the system will automatically generate a query link.
We will send this link to the customer.

For grade A, EVE tests&matches the cells, and they just tell us the test results, no how to test&match them.
For grade B (bulk cell), the test capacity is an option. It requires extra fees. If a customer needs that,we will test the cells

Link for CURRENT Grade-A Level:

Eve Fully Matched Genuine Grade A 3.2v 280ah Lifepo4 (lfp) Cells Battery With 6000cycles Large Terminals Luyuan - Buy Solar System 389a Button Cell Battery 280v Lifepo4 Battery Product on Alibaba.com

Eve Fully Matched Genuine Grade A 3.2v 280ah Lifepo4 (lfp) Cells Battery With 6000cycles Large Terminals Luyuan - Buy Solar System 389a Button Cell Battery 280v Lifepo4 Battery Product on Alibaba.com

www.alibaba.com

Below are how the B-ESS Grade Cells are shipped without Reports.

NOTE: Screws / Bussbars.

FYI: Luyuan was the FIRST VENDOR to offer:
- such public Factory Reports and purchases ONLY from EVE, no brokers or middlemen. reports,
- the Enhanced Packaging for cells to reduce Damage during shipping & YES it is slightly more costly that the OLD 4 Cells per box.
- Was the FIRST to Offer Busbars, Screws (Even doubled up for DIYSolfar Forum Customers when stated where they came from)
- Published & Included the https://diysolarforum.com/resources/luyuan-tech-basic-lifepo4-guide.151/ which is included with the Cells.


YES I wrote that for HERE AND gave that to Luyuan to include + to Promo DIYS. For No COMPENSATION ! of any kind (Like BMS Manuals for Chargery Co, and Others, ALL for FREE... WHY Because I am NOW 6-8 months from DYING cancer... So DO NOT Argue with it!

Hope it Helps & Clarifies and I do not care What others have copied from Luyuan.
They are Still one of the Most Honourable you will find out there, Period.

FYI: Luyuan was the FIRST VENDOR to offer:
- making such public Factory Reports and purchases ONLY from EVE, no brokers or middlemen. reports,
- the Enhanced Packaging for cells to reduce Damage during shipping & YES it is slightly more costly than the OLD 4 Cells per box.
- Was the FIRST to Offer Busbars, and Screws (Even doubled up for DIYSolfar Forum Customers when stated where they came from)
- Published & Included the https://diysolarforum.com/resources/luyuan-tech-basic-lifepo4-guide.151/ which is included with the Cells.

YES I wrote that for HERE AND gave that to Luyuan to include + to Promo DIYS. For No COMPENSATION ! of any kind (Like BMS Manuals for Chargery Co, and Others, ALL for FREE)

Hope it Helps & Clarifies
I do not care What others have copied from Luyuan.
They are Still one of the Most Honourable you will find out there, Period.

Steve.

 

[Steve_S]

! REMEMBER !
LFP Full Voltage Curve is from 2.500 Volts to 3.650 Volts per cell.
LFP Working Voltage is from 3.000 Volts to 3.400 Volts Per Cell. 3.200 Volts per cell is the Nominal Voltage (aka 50%).
* The Working Voltage is what provides you with the Amp Hours from the Cells.
* Below 2.950 is the "Cliff Fall" Above 3.430V is "The Cliff Climb".
Charge to 3.600, Saturate a cell till it takes < 5A and it WILL settle to 3.400 +/- pending on Cell Grade within 60-90 minutes.
Charging & Saturating to 3.425-3.430 will prevent Runner Cells and keep them in MAX Optimal Physical Health with little detrimental effect, it is "Technically" INSIDE the Gross Full Working Voltage !

Charging is at Constant Current & Constant Voltage (CC/CC), which get's you 95% of the way properly configured.
Topping to "100%" takes Constant VOLTAGE & Variable Current (CC/CV), so it decreases as the cells Saturate to Full set Voltage.
** This is called FLOAT ! which is CV/Variable Current

General LiFePO4 (LFP) Voltage to SOC charts/tables 12/24/48V

I've looked at several places for a simple, easy to read at a glance "chart document" for LFP. I could not find anything comprehensive. I discovered an XLS Worksheet in my stored file and took parts of that to create this chart, I did not...

diysolarforum.com

Hope it Helps & Clarifies and ends the pettiness arguments, in favour of Facts !
Steve

 

[Steve_S]

reserved-2

 

[Amy Wan]

Dear Steve,

We are always grateful for your selfless help! I know,you never hope any compensation,but I think the best reward is just sticking to who we are, always being an honest seller, and continuing to provide quality products and services.

Take care,

Amy Wan

 

[Symbioquine]

This thread should be sticky! I went with Shenzhen Luyuan based on reading reviews on this forum and haven't regretted it for a moment. My first batch of cells has been in place for a season and is working flawlessly. I'm now working on placing a larger order to expand my capacity. Communication has been clear and prompt. Cells were very well packaged and - other than sea freight issues beyond their control - were shipped and delivered as promised.

 

[Alkaline]

What cells did you order, if you got 280K please do a capacity test and post both your WH and AH ratings.

 

[Symbioquine]

What cells did you order, if you got 280K please do a capacity test and post both your WH and AH ratings.

The first batch of cells are EVE LF280K. Due to time pressure I didn't do an initial capacity test. That said, the cells are a year old and partially cycled daily in an off-grid system that powers some critical loads. I know they still have at least 260 Ah capacity currently because on 2022/11/08 they got discharged down by 261 Ah according to my BMS' and shunts - due to several successive days cloudy weather before I was forced to run the generator. The minimum cell voltage between both 8S batteries at that point was 3.136v so there should be a fair bit more capacity in the knee region of the discharge curve, but I didn't want to risk downtime or unnecessary wear on the cells from over-discharging them.

Once I get the new cells I hope to have the flexibility to slowly build and capacity test the new packs, then rebuild/rebalance and capacity test the old packs. I'll report the results once I've got them. (Probably in a new thread to avoid cluttering this one.)

 

[Alkaline]

what did you order matched & batched or the grade B?

 

[Symbioquine]

what did you order matched & batched or the grade B?

Yep, Grade A - Fully Matched

 

[SoggyShoes]

@Steve_S , first I am glad to see that you are still around and kicking. I really hope you are in remission.
I basically told Amy that I wanted batteries like yours, to the point I followed you on the single terminals. So thanks for the general guidance and in your responses to my questions.
I also would have never ordered anything on Alibaba without the reassurance from forum members like you. But, so far, Amy has been awesome!

The reason I am reviving this old thread is that Amy is (hopefully) shipping my order as I write this and she sent me the battery testing data. I tried looking on the internet and this forum to understand what all this means. I see that the OCV1, OCV2, and OCV3 are "open current voltages" and then the r1 and so on, is the resistance. But I still don't exactly know what the numbers are supposed to be and mean.
Are they just charging up the cells to some level (I am not sure what) and letting them sit until the voltage is stabilized or for a set time? And then does Amy (Luyuan) keep doing that until they find ones that match to make an order?

This is a link to a spreadsheet of the batteries that Amy is sending me: https://docs.google.com/spreadsheets/d/1XdWtRed29Cy6afC1G-I7yq0VwhMmbnrZPquGdiC0YrA/edit?usp=sharing
Ignore some some of the stats and colors - unless they help explain things or are what I should be looking for. I had the spreadsheet open when I had to help someone with making formulas in a spreadsheet. The shaded values are within one standard deviation of mean.

Are these values good? What should I be looking for?

I appreciate any help.
Thanks

 

[S Davis]

You want the cells resistance to match across the voltage range. That test report shows the resistance values at different voltages to show they match and will charge and discharge at the same rate.

 

[Steve_S]

Yep still around but interacting far less than before and far more picky about it too...
Surprised you found & revived this thread... I guess I'll get some more hating msgs again...
Please download that spreadsheet and keep it for reference. Make a folder on your computer and put all the docs, info/specs etc that Amy is providing, including copies of related material. Comes in handy when tracking planning etc but afterwards when you need/want that info. The spreadsheet data is from the EVE Testing Cycle where they evaluate & qualify the cells and Amy uses that to Match & Batch the cells.

I have dealt with a lot of Chinese vendors since the very early 1990's (computer related +) and have some experience you might say, and I've seen things people can't even imagine. Amy is really one of the rare few genuinely "Honourable" people. In fact this is one the primary reasons I chose to help her and Luyuan get going and doing well. I have Very Rarely done so and only for those worthy...

My cases were the First Batch with that customization and the couple of minor annoyance things got solved so less hassle.
Note a gotcha: If 8S Config, the pressure plate / BMS Mount can be fully tightened against the side & center support and with 280AH cells they are loose a little, foam pads fix that and now sent with kit. The Gotcha is the upper support bars (case) the holes do not line up precisely because it is 5mm too long (general supports intended for several cell sizes) so I used Self-Tapping Screws to secure the braces to the BMS Mounting plate. !!! Be careful of the wee bits of metal that results, you don't want that in your BMS or something...

 

[SoggyShoes]

You want the cells resistance to match across the voltage range. That test report shows the resistance values at different voltages to show they match and will charge and discharge at the same rate.

So does that mean the important data is that the Ri#(mohm) all match?

Is it important that the capacity or OCV1, OCV2, or OCV3 match?

My Ri1(mohm) are all the same except one cell is 0.01 lower, but my Ri2(mohm) & Ri3(mohm) are all exacly the same. So that's good right?

 

[Steve_S]

Those are really good cells. 0.01 is NOT significant but stick that inside the pack, not on the (+) or (-) take off cells.

Now as a point of note: Regardless of cell grade & rating & production date, I will ALWAYS top Charge the cells in batches of 4 to 3.650 and let them go until Charge Amps taken is down to 2A. I allow them to settle in parallel while I do the next 4. Once 8 are done, I hook them all up in parallel and taken them back to 3.650 an allow then to drop to around 5A before assembly to pack with BMS. This has always worked fo me, even with true use EV LFP cells (had a batch of them). I never see any great deviations between cells or packs but then again I run a Safe Moderate Charge & Discharge profiles in all of my devices and have taken the painstaking time to ensure correct Calibration & Compensations to ensure what the Battery Terminals see is what is being dealt with by the SCC's & Inverter system.

A note on Factory Tests. They test cycle the cells to set voltage points & read the IR at those points. Keep in mind that Manufacturers test their cells within the Working Voltage Range (3.000-3.400) and NOT the Allowable Range (2.500-3.650). The reality many forget is that cells are supposed to deliver the Spec'd AH Rating FROM the Working Voltage Range, if they fail that, instant B-Cell ! These tests are also done at a fixed 25C/77F temp because that is the optimal baseline reference temp.

 

[SoggyShoes]

Yep still around but interacting far less than before and far more picky about it too...
Surprised you found & revived this thread... I guess I'll get some more hating msgs again...
Please download that spreadsheet and keep it for reference. Make a folder on your computer and put all the docs, info/specs etc that Amy is providing, including copies of related material. Comes in handy when tracking planning etc but afterwards when you need/want that info. The spreadsheet data is from the EVE Testing Cycle where they evaluate & qualify the cells and Amy uses that to Match & Batch the cells.

I have dealt with a lot of Chinese vendors since the very early 1990's (computer related +) and have some experience you might say, and I've seen things people can't even imagine. Amy is really one of the rare few genuinely "Honourable" people. In fact this is one the primary reasons I chose to help her and Luyuan get going and doing well. I have Very Rarely done so and only for those worthy...

My cases were the First Batch with that customization and the couple of minor annoyance things got solved so less hassle.
Note a gotcha: If 8S Config, the pressure plate / BMS Mount can be fully tightened against the side & center support and with 280AH cells they are loose a little, foam pads fix that and now sent with kit. The Gotcha is the upper support bars (case) the holes do not line up precisely because it is 5mm too long (general supports intended for several cell sizes) so I used Self-Tapping Screws to secure the braces to the BMS Mounting plate. !!! Be careful of the wee bits of metal that results, you don't want that in your BMS or something...

I found the thrad because as a newbie I did try to figure this stuff out, but unfortunately am still confused and am hoping for more help from the battery wizards like you.

I appreciate all the work you did with Amy and reassurance for newbies like me that it is safe and worthwhile to work with her.
I am getting the same battery case and faceplate as you down to the single bolt terminals.

My cells are the new terminal EVE 304Ah from Amy which look to be the same size as the 280Ah cells. So it sounds it would be safer to tap the BMS screws and then install the BMS. The thought of loose metal shavings anywhere inside the battery box or even near the cells or BMS is terrifying.
In your "gotcha" would it be better to use a more rigid material to fill the gap like a thick piece of HDPE (cutting board material) so the box can give better compression?

Also, did you put a heat pad in yours? If so where did you mount the heating pad and the BMS temperature sensors?
Mine will be I'm the basement of my class-A RV and we do use it in the winter. I did get the new JK-BMS with the socket to control a heating plate. I have seen some debate on the forum about having the BMS control the heating pad or a separate independent relay.
Do you put the heating pad directly against the cells or use some kind of separator?

Sorry to bomb you with questions, but I this is my first battery build. This seems like something that needs to be 100% correct!
I am both nervous and super excited! My wife thinks it's funny that I am acting like a kid about to get their first bike (or maybe first iPad for today's generation).

 

[SoggyShoes]

Those are really good cells. 0.01 is NOT significant but stick that inside the pack, not on the (+) or (-) take off cells.

Now as a point of note: Regardless of cell grade & rating & production date, I will ALWAYS top Charge the cells in batches of 4 to 3.650 and let them go until Charge Amps taken is down to 2A. I allow them to settle in parallel while I do the next 4. Once 8 are done, I hook them all up in parallel and taken them back to 3.650 an allow then to drop to around 5A before assembly to pack with BMS. This has always worked fo me, even with true use EV LFP cells (had a batch of them). I never see any great deviations between cells or packs but then again I run a Safe Moderate Charge & Discharge profiles in all of my devices and have taken the painstaking time to ensure correct Calibration & Compensations to ensure what the Battery Terminals see is what is being dealt with by the SCC's & Inverter system.

A note on Factory Tests. They test cycle the cells to set voltage points & read the IR at those points. Keep in mind that Manufacturers test their cells within the Working Voltage Range (3.000-3.400) and NOT the Allowable Range (2.500-3.650). The reality many forget is that cells are supposed to deliver the Spec'd AH Rating FROM the Working Voltage Range, if they fail that, instant B-Cell ! These tests are also done at a fixed 25C/77F temp because that is the optimal baseline reference temp.

I guess I feel like the data sheets are a "trust but verify" item.

So is what you described a top balancing or just a "top charging"?
Also, do you have a good recommendation for a bench charger to do this?

 

[Steve_S]

The 304's are NOT the same size, very close though, I believe they are a pinch taller.

I used the old trick of adhesive under the metal to catch the fillings but then air compressor air blow etc too. I'm nuts about that. Had I known (lesson learned pack 1) it would have tapped it first.

Amy is now providing the good foams with the kits, I did not get any as I didn't ask but now she's including them by default. I used a mesh foam on the sides (between FR4 & case sides) & in front between the FR4 & BMS Plate. Snig but NOT compressed heavily, no need to.

No Heating for me. My Powerhouse is a separate heated and hyper-insulated structure similar to my house with Broken Thermal Walls & Roof and Frost Protected Slab Foundation that has radiant pex in it (for future solar fluid heating) etc. Now I have systems & packs going into the "wild" and a Silicone Heating Pad can be available for those, controlled by BMS as each pack is independent and subject to its own. I would isolate the Silicone by sandwiching it between FR4 sheets.

As I am 24V, I only used Harness 1 & 2, so only 2 Temp Sensors. One in back & one in front. The BMS complains that only 2 sensors are there but that's a software patch to be done.

BEWARE OF PADDING USED ! do not think you need more than you really do. The foam I used is neutral (chemically it is food safe even) and is VERY Thin, 2mm thick BUT as a mesh is compressed very nicely & evenly. It won;t get gooey with high temps or cause issues. AMY will be sending thin foam rubber fillers and you only need to ensure the cells are SNUG and not over pressed.

A GOTCHA that many forget... It is best to install cells KNOWING that they naturally will expand & contract with charge level & temps, it is actually best to install & build you packs at 25C/77F temp & with cel sat 3.200V (nominal for voltage/temp & size - mid point of expansion/contraction). I did one pack at 100% and when it got to 3.0Vpc the cells were looser. I did another pack with cells at 3.000Vpc and when fully charged to 3.450 they were quite Tight- So apply the law of averages for the safest outcome.

My process of charging is Top Charging & Tp Balancing but I take no short cuts cause they cause more issues than worth. Sure it takes longer but patience is ALWAYS REWARDED where Haste ALWAYS MAKES WASTE ! Not to mention all the hair one pulls out during the problems & quirks stage. BTDT and almost have no hair left ! OKAY some of that is age related but Shhhhhh don't tell anyone.

I am using a TekPower TP1540E Bench supply that outputs 40A CC/CV and woks a treat. BUT I got this BEFORE the EBC-A40L units came available ! A new TekPower unit will cost you as much as an EBC40 but without the extra goodies. I have recommended to people to get the EBC unit because you can do Charge & Discharge tests which it reports & can be used with the PC Software to test & validate cells and more.

 

[SoggyShoes]

The 304's are NOT the same size, very close though, I believe they are a pinch taller.

I used the old trick of adhesive under the metal to catch the fillings but then air compressor air blow etc too. I'm nuts about that. Had I known (lesson learned pack 1) it would have tapped it first.

Amy is now providing the good foams with the kits, I did not get any as I didn't ask but now she's including them by default. I used a mesh foam on the sides (between FR4 & case sides) & in front between the FR4 & BMS Plate. Snig but NOT compressed heavily, no need to.

No Heating for me. My Powerhouse is a separate heated and hyper-insulated structure similar to my house with Broken Thermal Walls & Roof and Frost Protected Slab Foundation that has radiant pex in it (for future solar fluid heating) etc. Now I have systems & packs going into the "wild" and a Silicone Heating Pad can be available for those, controlled by BMS as each pack is independent and subject to its own. I would isolate the Silicone by sandwiching it between FR4 sheets.

As I am 24V, I only used Harness 1 & 2, so only 2 Temp Sensors. One in back & one in front. The BMS complains that only 2 sensors are there but that's a software patch to be done.

BEWARE OF PADDING USED ! do not think you need more than you really do. The foam I used is neutral (chemically it is food safe even) and is VERY Thin, 2mm thick BUT as a mesh is compressed very nicely & evenly. It won;t get gooey with high temps or cause issues. AMY will be sending thin foam rubber fillers and you only need to ensure the cells are SNUG and not over pressed.

A GOTCHA that many forget... It is best to install cells KNOWING that they naturally will expand & contract with charge level & temps, it is actually best to install & build you packs at 25C/77F temp & with cel sat 3.200V (nominal for voltage/temp & size - mid point of expansion/contraction). I did one pack at 100% and when it got to 3.0Vpc the cells were looser. I did another pack with cells at 3.000Vpc and when fully charged to 3.450 they were quite Tight- So apply the law of averages for the safest outcome.

My process of charging is Top Charging & Tp Balancing but I take no short cuts cause they cause more issues than worth. Sure it takes longer but patience is ALWAYS REWARDED where Haste ALWAYS MAKES WASTE ! Not to mention all the hair one pulls out during the problems & quirks stage. BTDT and almost have no hair left ! OKAY some of that is age related but Shhhhhh don't tell anyone.

I am using a TekPower TP1540E Bench supply that outputs 40A CC/CV and woks a treat. BUT I got this BEFORE the EBC-A40L units came available ! A new TekPower unit will cost you as much as an EBC40 but without the extra goodies. I have recommended to people to get the EBC unit because you can do Charge & Discharge tests which it reports & can be used with the PC Software to test & validate cells and more.

Thanks.
I want to take the time to do it right. We like dispersed camping (or whatever it is in an RV that is bigger and nicer than my first apartment). So we are often in the middle of nowhere with my wife and kids. With such valuable cargo, it is critical to me that I can rely on being safe and things just working.
I just think until I have everything in front of me and start preparing the cells and putting thr battery together, it is going to feel a little confusing. So until the slow boat from China arrives, I am spending my time preparing and learning all that I can.

By far the hardest part of ordering from Amy is the wait! That is agonizing! I'm trying to make the best of it by spending way too much time on this forum (while harping on my kids to get off their screens). LOL

 

[Steve_S]

The wait is a test of patience and a reminder of days past when the world was a bit slower and calmer too. But I'm a geezer so... The "Instant Rice Society" thing is too much for me, everything wanted "right away" and then grumble about the consequences....

 

[S Davis]

The wait is a test of patience and a reminder of days past when the world was a bit slower and calmer too. But I'm a geezer so... The "Instant Rice Society" thing is too much for me, everything wanted "right away" and then grumble about the consequences....

Just about nobody has patience anymore, my first batch of cells I paralleled and top balanced the first couple 12volt batteries 72-75 hours per pack.

I then decided I didn’t need to take the time. Guess what, the two packs I took the time on are my best balanced batteries, they stay within .015 of each other and the others from the same batch of cells the BMS has to balance on every charge cycle.