Luyuan / Amy - Type 66 & 71 in matched set?

Just John

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Right but what I was getting at is if all the cells come with 291ah's capacity, and are run through a few cycles, will the capacity of the cells remain relatively close to each other? I know the capacity of all the cells will drop some.

I didn't capacity test all of my 8 cells. My weakest cell when I received them was 272ah's. I too have run them with low C rates and they perform well.
I've broken apart my packs and tested the cells individually over the past 10 months, to see exactly that.
They seem to degrade at the same rate, and thus maintain the same difference. Base on testing cells individually at 40 amps, 8 times over 10 months so far.
 

Gazoo

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I've broken apart my packs and tested the cells individually over the past 10 months, to see exactly that.
They seem to degrade at the same rate, and thus maintain the same difference. Base on testing cells individually at 40 amps, 8 times over 10 months so far.
Thanks. I always wondered about that and now I don't have to...lol.
 

Gazoo

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BTW, my load tester came in today. I am charging the 289 to 3.65v and then will load test it. Due to my ineptness, you will likely hear me saying I blew something up.
No don't blow anything up. I look forward to your results. Just keep in mind when you load test the cell the tester will shut off before the cells actual voltage measured at the cells terminals reaches 2.50 volts due to voltage drop. So you might want to set the tester at 2.3 volts and babysit the cell towards the end of charge and keep an eye on the cells voltage.
 

Stepandwolf

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No don't blow anything up. I look forward to your results. Just keep in mind when you load test the cell the tester will shut off before the cells actual voltage measured at the cells terminals reaches 2.50 volts due to voltage drop. So you might want to set the tester at 2.3 volts and babysit the cell towards the end of charge and keep an eye on the cells voltage.
Thanks for the tip....I briefly looked at the instruction sheet and quickly determined I won't be able to use it. Will check Will's video and see if I can figure it out. Do you have a feeling for how many hours it might be to reach 2.3V?
 

Gazoo

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Thanks for the tip....I briefly looked at the instruction sheet and quickly determined I won't be able to use it. Will check Will's video and see if I can figure it out. Do you have a feeling for how many hours it might be to reach 2.3V?
Never used one. I am sure someone else will chime in that has.
 

HighVolt

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I think I have explained it clearly to you, right? According to the matching standard of EVE, it is normal for the cell capacity difference in each group to be within 5.6AH.

Yes you have told me after the latest batch of cells shipped and I queried. The order supplied previously, cell capacity difference of 0.42 AH or 0.15%. So the ~2% variation on the latest order is unexpected.

I'd be surprised if qualified grade a cells, manufactured in a single batch have a variation of much more than 2%. This is why I question if they are "fully balanced" as opposed to just being grade a cells. I don't know a lot about the manufacturing process but it just seems strange to me.
 

Just John

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Thanks for the tip....I briefly looked at the instruction sheet and quickly determined I won't be able to use it. Will check Will's video and see if I can figure it out. Do you have a feeling for how many hours it might be to reach 2.3V?
It isn't difficult to get close. If you test at 20 amps, a 280AH cell should take 14 hours. I do recommend 15 amps, otherwise be careful and don't burn your fingers. I also used 2.3v as cutoff, BTW. I think (if they really are about a year old) that they will measure closer to 280 than 290, but that would be normal. They seem to drop several amp hours in capacity in the first couple of cycles, then level off after a few cycles. Eve recommends you cycle them every 6 months if they are stored. Other than that, at least the data you were given indicates well matched top quality cells. You shouldn't have any problems with them at .5C rates.
 

Miles B

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I'd be surprised if qualified grade a cells, manufactured in a single batch have a variation of much more than 2%.

Honest question: what do you base this idea upon?

As an electrical engineer, the things I am looking for are absolute closeness of internal resistance, and a capacity within a few percent would be more than close enough for me to call these "matched". These cells are likely tested by different machines on different days. Measuring total energy output is not an exact affair. There are many different ways of measuring it, this is not like measuring resistance or open circuit voltage or distance or mass. Two identical cells could measure a little different at different temps or on different machines, with slight differences of internal components or algorithms. Would you prefer if they just retested these cells over and over until they got one run with the value you want? Because it's absolutely possible to do that, with lithium batteries and energy calcs.

I came here because I've been looking for a reliable source for cells from China. I've bought stuff from there before and I know how difficult it is to find anyone even remotely reliable, with any kind of customer service. What I'm reading from the experiences with this seller look pretty pleasing to me so far. I absolutely encourage you to keep this seller honest, but also beware that unreasonably chasing her over things that don't matter is also self defeating. 2% difference on cell capacity measurement, in my educated opinion, is very reasonable, and I will not be worried about it when I make my order. Also, waiting a few days or a week to hear back on an update about specialist freight is entirely reasonable and expected too. I have had a good deal of experience with shipping this way, and it is not just a matter of entering a tracking number in a website. Make sure your supplier looks after you, but if you've got a good supplier, make sure you look after them too.
 

Just John

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I came here because I've been looking for a reliable source for cells from China. I've bought stuff from there before and I know how difficult it is to find anyone even remotely reliable, with any kind of customer service. What I'm reading from the experiences with this seller look pretty pleasing to me so far. I absolutely encourage you to keep this seller honest, but also beware that unreasonably chasing her over things that don't matter is also self defeating. 2% difference on cell capacity measurement, in my educated opinion, is very reasonable, and I will not be worried about it when I make my order. Also, waiting a few days or a week to hear back on an update about specialist freight is entirely reasonable and expected too. I have had a good deal of experience with shipping this way, and it is not just a matter of entering a tracking number in a website. Make sure your supplier looks after you, but if you've got a good supplier, make sure you look after them too.

My thoughts exactly. I'm sure Amy doesn't peruse the cell numbers nearly as close as we do, she just depends on Eve to send her closely matched cells. I have confidence she would replace the two cells if they physically don't match (i.e. one is 4mm taller). If they fail to meet the advertised spec or capacity, Eve has a problem (and Amy does as well, but she didn't cause the problem). I'm sure Eve regards her as small fry, and won't bend over backwards to assist (and thus assist us).

When he receives the cells, I'd be very interested in any test results. Until then, it does little good and is counterproductive to beat up Amy for a problem (we aren't even sure it is a problem yet) that she didn't cause. All we really know is that the cell version number does not match on two cells, and Eve has published a spec sheet that implies it is a "version" that (we think) hasn't been manufactured in a year or more. I suspect Eve might in the future stop including the "decoder" in any new spec sheets if it causes a big problem.

I am also concerned that Amy might decide there is an easier way to earn a living. She is a very reliable vendor, and I would hate to lose her, and start playing roulette with other vendors.

Anyway, I have some spare test equipment if the person that has two "66" cells on the way needs to borrow some, the cheap heater testers I'd even be willing to donate if he lives in the USA. I have some much more expensive testers, but I'd be willing to loan out if necessary just to verify the cells meet spec. I'd hate to think Eve is shipping out cells a year old without retesting, but it seems possible just based on the serial numbers. I also find it interesting that Basen is shipping the same version as brand new with test results, and saying they were manufactured in June this year. I don't know what is going on, but something interesting is going on based on the cell version numbers, plus the fact Basen suddenly has a 2000 lot of cells with the same version number and test results.
 

Stepandwolf

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It isn't difficult to get close. If you test at 20 amps, a 280AH cell should take 14 hours. I do recommend 15 amps, otherwise be careful and don't burn your fingers. I also used 2.3v as cutoff,
Hello JJ, A day later, I am still charging the first cell. Was at 9a charge last night, down to 7-8a now. Still concerned about how to operate the tester. I did notice that just applying power to the load tester the display didn't turn on. Thought without the battery to test being connected the device would still power up. Hope it isn't bad.
BTW. I think (if they really are about a year old) that they will measure closer to 280 than 290, but that would be normal. They seem to drop several amp hours in capacity in the first couple of cycles, then level off after a few cycles. Eve recommends you cycle them every 6 months if they are stored. Other than that, at least the data you were given indicates well matched top quality cells. You shouldn't have any problems with them at .5C rates.
What makes me wonder about the year thing is the spreadsheet. If the EVE spreadsheet was created in June showing all the test results per cell, do you think the data is from a year ago or did EVE recently test the cells before delivering them? Likewise with MrProton's order with a mix of 66 and 71 cells. Do you think they tested his 66s a year ago, and the 71s six months ago for his order? I don't think Luyuan provided the full spreadsheet like Basen did so we don't know the date they received the cells. Likewise, we don't know if they had 66s laying around from a previous order and threw them in with more recent 71s.

It seems that both Basen and Luyuan ordered "matched cells"?, were given the spreadsheet, and provided the batteries. I know when I asked Basen about matching and they said it was done in China, but they didn't say THEY did the matching. Given how things are breaking down on these orders, I am not convinced the vendors are doing anything but boxing and shipping the batteries. At least with Luyuan, they knew the cells they shipped. Basen didn't track what cells were sent to me so they gave me the full 2000 cell spreadsheet to find my own cells in the list.

If the spreadsheet is authentic and was generated by EVE in June, it would seem that was when they provided the batteries, in my case, to Basen. Due to some ignorance on the difference between mfg date vs. ship date, Basen insisted they were made in June. Either way, did EVE test before shipping or a year ago?
 

DerpsyDoodler

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... 2% difference on cell capacity measurement, in my educated opinion, is very reasonable, and I will not be worried about it when I make my order. Also, waiting a few days or a week to hear back on an update about specialist freight is entirely reasonable and expected too. I have had a good deal of experience with shipping this way, and it is not just a matter of entering a tracking number in a website. Make sure your supplier looks after you, but if you've got a good supplier, make sure you look after them too.
Is 5% just as reasonable?
 

Stepandwolf

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My thoughts exactly. I'm sure Amy doesn't peruse the cell numbers nearly as close as we do, she just depends on Eve to send her closely matched cells. I have confidence she would replace the two cells if they physically don't match (i.e. one is 4mm taller). If they fail to meet the advertised spec or capacity, Eve has a problem (and Amy does as well, but she didn't cause the problem). I'm sure Eve regards her as small fry, and won't bend over backwards to assist (and thus assist us).
I looked back at my quote from Amy and she never mentioned battery version. All the dialogue simply said LF280. As I just mentioned, it doesn't/didn't seem like Amy knew about the model differences and did a mixed shipment.
When he receives the cells, I'd be very interested in any test results. Until then, it does little good and is counterproductive to beat up Amy for a problem (we aren't even sure it is a problem yet) that she didn't cause. All we really know is that the cell version number does not match on two cells, and Eve has published a spec sheet that implies it is a "version" that (we think) hasn't been manufactured in a year or more. I suspect Eve might in the future stop including the "decoder" in any new spec sheets if it causes a big problem.
I would think as the vendors order, they would be asking for specific versions and would within their system distinguish between versions. I don't know that any of this dialogue will get back to EVE, but I would hope all of the vendors will understand there is a difference in models, not just physical dimensions. EVE obviously is doing cell redesign which could even involve different chemistries between versions.
Anyway, I have some spare test equipment if the person that has two "66" cells on the way needs to borrow some, the cheap heater testers I'd even be willing to donate if he lives in the USA. I have some much more expensive testers, but I'd be willing to loan out if necessary just to verify the cells meet spec. I'd hate to think Eve is shipping out cells a year old without retesting, but it seems possible just based on the serial numbers. I also find it interesting that Basen is shipping the same version as brand new with test results, and saying they were manufactured in June this year. I don't know what is going on, but something interesting is going on based on the cell version numbers, plus the fact Basen suddenly has a 2000 lot of cells with the same version number and test results.
As I just mentioned, Basen didn't know the distinction between ship date and mfg date. So when Basen was claiming these were "made in June", they really meant they received them in June. But Basen also said EVE was out of batteries from March to June. If that was the case, then where did EVE comes up with these from? What is clear that EVE provided both Basen and Luyuan with these 66s. If EVE is still shipping these batteries that it was assumed haven't been made for a year, then we have more to find out than we know now.
 

Miles B

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Is 5% just as reasonable?
Has Amy supplied cells with 5% variance?

NOBODY here knows what a different serial number range means. It could mean ANYTHING. It could mean they are using up older casings on newer cells because the physical size hasn't changed. It could mean NOTHING. Their machinery may be pulling serial number ranges from a database and there were gaps.

You are all making huge assumptions and hassling the best supplier you've had. Does any of it even matter? Do you pull apart every box of everything you buy and then demand an explanation why your products appear to be slightly out of range numbers? None of this will make your battery run better.

Look at the internal resistance, condition, capacity and anything else functional. Consecutive serial numbers aren't functional.
 
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DerpsyDoodler

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Has Amy supplied cells with 5% variance?

NOBODY here knows what a different serial number range means. It could mean ANYTHING. It could mean they are using up older casings on newer cells because the physical size hasn't changed. It could mean NOTHING. Their machinery may be pulling serial number ranges from a database and there were gaps.

You are all making huge assumptions and hassling the best supplier you've had. Does any of it even matter? Do you pull apart every box of everything you buy and then demand an explanation why your products appear to be slightly out of range numbers? None of this will make your battery run better.

Look at the internal resistance, condition, capacity and anything else functional. Consecutive serial numbers aren't functional.
According to at least 1 poster, the spread they're receiving is 5%. Or have you not been reading the same thread that I have?
 

Miles B

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According to at least 1 poster, the spread they're receiving is 5%. Or have you not been reading the same thread that I have?

I'm not seeing a report of 5%. Could you point me towards the post number? Or is it a different thread?
 

Just John

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Hello JJ, A day later, I am still charging the first cell. Was at 9a charge last night, down to 7-8a now. Still concerned about how to operate the tester. I did notice that just applying power to the load tester the display didn't turn on. Thought without the battery to test being connected the device would still power up. Hope it isn't bad.

I just checked one of mine (it's been at least 6 months since I played with one) and it should turn on as soon as you plug in the power supply.


What makes me wonder about the year thing is the spreadsheet. If the EVE spreadsheet was created in June showing all the test results per cell, do you think the data is from a year ago or did EVE recently test the cells before delivering them? Likewise with MrProton's order with a mix of 66 and 71 cells. Do you think they tested his 66s a year ago, and the 71s six months ago for his order? I don't think Luyuan provided the full spreadsheet like Basen did so we don't know the date they received the cells. Likewise, we don't know if they had 66s laying around from a previous order and threw them in with more recent 71s.

Really hard to tell about the testing, their data available to me does not indicate any test date is recorded. I'm sure all of the recent cells are just in a big database, and results are just pulled out by serial number, in Amy's case, likely by order number. Luyan just provides a link where Eve displays what is on the order, I'm sure if I had ordered 2000 cells, all 2000 would be on it. After a certain amount of time, the database is purged, so the remaining data is just the shipped measurement of cell voltage, IR, and measured capacity. When I first access mine, it had the entire range filled in, then after a few months only the measurement was left.

It seems that both Basen and Luyuan ordered "matched cells"?, were given the spreadsheet, and provided the batteries. I know when I asked Basen about matching and they said it was done in China, but they didn't say THEY did the matching. Given how things are breaking down on these orders, I am not convinced the vendors are doing anything but boxing and shipping the batteries. At least with Luyuan, they knew the cells they shipped. Basen didn't track what cells were sent to me so they gave me the full 2000 cell spreadsheet to find my own cells in the list.

If the spreadsheet is authentic and was generated by EVE in June, it would seem that was when they provided the batteries, in my case, to Basen. Due to some ignorance on the difference between mfg date vs. ship date, Basen insisted they were made in June. Either way, did EVE test before shipping or a year ago?

From my (admittedly limited) experience, as long as they were stored at the correct storage state of charge (and reasonable temperatures), you won't get much degradation (my estimate would be less than 1% in 6 months, likely much less). It is entirely possible that cells were manufactured and tested in December of 2020, and would still meet grade A spec (i.e. at least 280AH capacity). Matched cells are where they attempt to match actual capacity and IR for use in a vehicle or other high C rate use case. I would cycle them as soon as possible, since Eve recommends that during storage every 6 months.

Summary, I don't think there will be any problems if the cells are 6 months old. Cycle them as soon as practicable, since Eve recommends it.
Measuring capacity will let you know right away if there was any degradation, and I would be very interested in the results. Most "loss" of capacity will be within the first 10 cycles or so, but it won't be that significant and should affect closely matched cells evenly. Be sure to test as close to 75 degrees Fahrenheit as possible. Depending on which spec sheet you read, .33C or .2C (94 or 56 amps) discharge rate should give you guaranteed 280AH capacity if measured in the first 5 cycles. When placed in a pack, all cells should hit limits (3.65v to 2.5v) very closely, and cells voltages in between should be extremely close (that's why they match cells). Grade A cells (not matched) should be pretty darn close as well, and at low C rates (like .2C) should perform just as well. It's when you get to the .5C rate and above that the matching is most noticeable.

Reading between the lines on the response Eve gave to Amy, it sounds like the changes in the "version" of the cell are primarily to comply with new vehicle rules/regulations in China (the primary consumer of these cells). Chevy Bolt pouch cells were recently recalled, and the new "version" is simply a tweak to the settings for the robot that does the tab connections, not to the actual cell, formulation, capacity, or even assembly.

Edit to add, when Eve ships cells, that spreadsheet tells you what voltage they were stored/shipped at after the test. So if you have an accurate meter, you can get a good idea how long it has been since they tested. Usually within a millivolt or two of 3.3v,
 
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MrPhoton

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I'm back now.

I want to say, thanks MrPhoton very much for this thread, and thanks everyone here very much for your attention to this topic.

Exploring the answer to this question is also a learning experience for me! So, thanks MrPhoton!

EVE replied to me today, and I will sort out their replies as follows:

1. About the code of the production date in the serial number:

We can’t directly find its production date through the serial number on the cell. It’s just a code. We can send this code to EVE. They can inquire all information about the cell through EVE internal software---(mens system) ,from the raw material to the finished product to send out to customers. Of course, the production date is included.

2. About the production date:

This involves EVE's production process.

The production date represented by the serial number on the cell refers to the date when it is put into raw materials and made into semi-finished products.

After being made into a semi-finished product, it will sit for a period of time (there is no special regulation for the specific siting time, the only criterion is whether it passes the test). Generally, the longer the siting time, the more accurate and stable the data.

After EVE receives customers' orders, they will use the semi-finished products that have passed the test manufacture to the finished products, and then test, match, and send out. In order to distinguish, we can define this date as the "manufacturing date"

Through EVE's inquiry, the semi-finished production date of the two "66" cells (02YCB66728600JACH0002569, 02YCB66728400JACG0021411) sent by MrPhoton is December 17, 2020. We ordered the batch cells at the end of June 2021 and received them in July, which means they have siting for about half a year.

3. About "66" and "71":

EVE replied that they are exactly the same cell, only due to the need of the new energy vehicle announcement file (their statement is very professional, sorry, I don't quite understand that), the cells are marked with the two numbers.

Through above 1 and above 2, we could know that if the serial numbers of the cells one customer received is almost or completely continuous, it will be untrue. Unless they are not really grade A, and not matched.

EVE matches the cells only based the test data, not based on the serial numbers.

4. About the "5.6AH" I mentioned

For grade A cells, meeting the specifications is the minimum requirement. So, I am not saying that its actual capacity can allow 280-5.6=274.4AH.

No, its actual capacity is around 289AH.

It's just that EVE has its own standard for matching. For the same group cells, they have strict regulations on the internal resistance difference, voltage difference and capacity difference. 5.6AH is the largest capacity difference allowed in their standard.

5.About the cells supply:

We report our estimated monthly demand to EVE, so they will reserve those for us.

In fact.according to our experience working with EVE, for real grade A cells, it will always be available, just with occasional delays in delivery.

EVE also asked me to convey to everyone, they kindly invited all of you to visit their factory!

This is a very helpful, nice and open platform. If all of you have any other questions, please feel free to contact me, through private conversation, email or Alibaba,all is ok.

Kind regards,

Amy

Hi Amy - Thank you for this very thorough response. The detail level is quite helpful.

It also sounds like an opportunity for EVE to update their PDF specifications to avoid buyer confusion. From the description, it sounds as though QR serialization date may be separate from electrolyte fill/finishing date. It would be interesting to contrast this with CATL and LISHEN standards.

Many thanks!
 

Stepandwolf

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I just checked one of mine (it's been at least 6 months since I played with one) and it should turn on as soon as you plug in the power supply.
Dummy me stuck the PS into the side connector, not on top, duh...
Really hard to tell about the testing, their data available to me does not indicate any test date is recorded. I'm sure all of the recent cells are just in a big database, and results are just pulled out by serial number, in Amy's case, likely by order number. Luyan just provides a link where Eve displays what is on the order, I'm sure if I had ordered 2000 cells, all 2000 would be on it. After a certain amount of time, the database is purged, so the remaining data is just the shipped measurement of cell voltage, IR, and measured capacity. When I first access mine, it had the entire range filled in, then after a few months only the measurement was left.
I am glad Basen was given and had a copy of the whole 2000 cell spreadsheet.
From my (admittedly limited) experience, as long as they were stored at the correct storage state of charge (and reasonable temperatures), you won't get much degradation (my estimate would be less than 1% in 6 months, likely much less). It is entirely possible that cells were manufactured and tested in December of 2020, and would still meet grade A spec (i.e. at least 280AH capacity). Matched cells are where they attempt to match actual capacity and IR for use in a vehicle or other high C rate use case. I would cycle them as soon as possible, since Eve recommends that during storage every 6 months.
Amy gave MrPhoto a 12/2020 date and my cells are in the same range. Prior to what Amy provided, everything I read indicated the stopped LF280 in July. I don't know if I have a way to cycle the batteries. My system isn't built, haven't even connected a BMS yet.
Edit to add, when Eve ships cells, that spreadsheet tells you what voltage they were stored/shipped at after the test. So if you have an accurate meter, you can get a good idea how long it has been since they tested. Usually within a millivolt or two of 3.3v,
I don't know how to interpret the three voltages values on the sheet that they just label v1, v2, and v3. For the battery I am testing, the values were 3.303, 3.302, 3.295. Initially, I only opened the first box and checked one cell, but a week ago I opened them all up to look them over. When I did that, every cell measured 3.36. That meter doesn't measure beyond that. Assumed the batteries didn't charge themselves since testing, the 3.303 value on the spreadsheet (and the other values) are after some test that decreased the voltage?

If I accept these batteries, I have to go through the arduous process of charging the bank with my 10A charger, whooopee, and that is after getting this first battery back to their 3.36v. Thanks very much for the detailed response!
 

PeterBC

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No sure where to best post this. I bought my cells (52 x 272Ah Lishen) from Gloria at Shenzen Basen on 31Dec20 DDP to France (98day delivery) USD 4691.00 DDP to France. . I'm happy enough with the 2 packs I had installed (remotely from Australia) with 24 cells each for 816AH x 24V nominal. Used Electrodacus SBMS0 BMS with Victron Quattro Inverter/Charger and Battery Protect for DC Load/charging control.

I'm often asked a bit by others what to recommend. I still feel very uncomfortable about the trust level from various providers and what exactly to say. My head spins re various Grades, manufacturers and resellers. I have several questions ? Many technical, some just commercial. By manufacturer below I refer to known companies like EVE, Lishen, CATL, CALB, Winston etc. What drives these questions ultimately is that there can be large variations in prices (3 to 1) of essentially the same item (eg EVE 280AH). How to know when one is getting a seriously sub standard product or service ? I know in some cases its a question of lead time/stock location, and ability to persue a refund if issues apply..

My questions..

1. It seems very few buy small quantities direct from a manufacturer ?

2. What do the manufacturers test after manufacturing ? Internal Resistance, and Capacity at a std charge/discharge rate and temperature ?

3. Is inital SEI layer charging done ? or does the initial manufacturer capacity test qualify as this ?

4. Do manufacturers do a capacity test on all individual manufactured cells ? At what charge/discharge rate ? Would they keep a record of individual QR code manufacturing test ?

5. Do manufacturers do above testing with compression ?

6. If a new cell is capacity tested without compression is bloating likely ? Does it indicate quality difference in cells ? Does a bloated cell have significantly reduced lifespan from a single 'bloat' case? Can bloating be reversed ?

7. What exactly is "matched" by manufacturers ? "Batched" ?

8. Are cells normally manufactured with the blue plastic film on ? Why do some 'resellers' claim to apply that themselves ? (as shenzen Basen claimed to do with my cells, and Battleborn video's show them doing)

9. Is the QR code on most batteries done by original manufacturer ? What about cells that fail initial IR test and/or Capacity test ? Are reputable resellers replacing QR codes? to hide initial manufacturer ID and test results ?

10. Do they just 'grade' them into batches ? Is a batch of 272AH cells, likely just some 280AH cells that failed capacity tests a bit ? Apart from a slightly lower capacity (how much ? 5%?) what is the other difference (Internal Resistance ?). Is a static IR test indicative of a significant issue with a cell ?

11. What happens if cells of similar tested capacity have significant IR difference in a pack ? Whats considered a significant IR difference ? Eg: EVE 280AH quote < 25mOhm IR. Lishen 272AH quote AC-impedance(1000Hz) 0.12±0.05mΩ. Is lower IR better ? or is consistency more important ? Is heat at high amps the main impact of IR ?

12. There are many 'rumors' about resellers selling 2nd hand cells. How to identify ? Are significant supplies coming as 2nd hand ? Clearly any reseller selling 2nd hand cells without clearly identifying them as so should be avoided at almost any cost. Have we reports of any proven cases ?

13. Apart from 2nd hand cells, and bloated cells, what is indicative of a lower lifespan than usual for a specific cell type ? Eg: if one cell has double the IR of others is it likely to have lower lifespan ?

14. What other outcomes are expected from non ‘Grade A’ cells in a pack ?


Thanks.. Peter
 
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