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EVE Specification Code "66", is this 280Ah ?

Mariner62

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I received 4x cells for my test system today, well packaged, all in good condition and reading 3.294V exactly. They appear to be EVE cells, and I've had a look at the EVE specification Rev A on this site to interpret the QR code.
The specification indicates that "Specification Code: 71" is a 280Ah cell. However my cells show "Specification Code: 66" on their QR labels.
Does anyone know what this means?

In case anyone is interested, these are the codes on my cells, interpreted according to the EVE Specification Rev A Attached.
Next step charge, top balance, build the pack and capacity test :)

EVE LFP Cells​

Arrived 7/1/2021

Voltages on Arrival: All Cells 3.294V exactly.

QR Codes

Cell
No.​
Serial Number​
Date Code​
Vendor Code​
Product Code​
Battery Code​
Specification Code​
Tracking Code​
Factory Address Code
1​
3570​
A5M​
02Y​
C​
B​
66​
722700​
J: Jingmen
2​
1867​
A3P​
02Y​
C​
B​
66​
713100​
J: Jingmen
3​
3655​
A63​
02Y​
C​
B​
66​
714400​
J: Jingmen
4​
1867​
A3P​
02Y​
C​
B​
66​
713100​
J: Jingmen
Codes:
Serial Numbers: Same specification cells produced on same day have the same serial numbers.
Date Code is Production Date: [A = 2020] [3=March/5=May/6=June] [3=3rd/M=22nd/P=25th/R=27th]
Vendor Code: 02Y = EVE.
Product Type Code: C= Single Cell.
Battery Type Code: B = Lithium Iron Phosphate
Specification Code: 66 = ???Ah (I know 71 = 280Ah from the Eve Spec).
Tracking Code: Factory production line and work order codes.
Factory Address Code: J = Jingmen, H = Huizhou.

Some Pics.
Eve1.jpeg

Eve2.jpeg
QR Codes 1.jpg
 

Attachments

  • EVE LF280N-72174 Specification.pdf
    682 KB · Views: 70
Date Code is Production Date: [A = 2020]
How did you determine A=2020?

Specification Code: 66 = ???Ah (I know 71 = 280Ah from the Eve Spec).
Most of us have received cells with a 66 code. They have tested between 265 to 280+ Ah's. As far as I know no one has been able to decipher what that code means. And no one has been able to decipher the date code although there has been plenty of speculation.
 
How did you determine A=2020?
In the Spec Rev A I attached, the example given for interpreting the Production Date is 87C = July 12 2018.
I considered this to be a Hex Code where 8 = 2018. 7= 7th Month and C =12th Day (Hex). I assume they started with a year epoch of 2010.

Most of us have received cells with a 66 code. They have tested between 265 to 280+ Ah's. As far as I know no one has been able to decipher what that code means. And no one has been able to decipher the date code although there has been plenty of speculation.
Ok, that's good to know. My cells are still charging at 20A, I guess they were pretty empty on arrival !

1609964135309.png
 
In the Spec Rev A I attached, the example given for interpreting the Production Date is 87C = July 12 2018.
I considered this to be a Hex Code where 8 = 2018. 7= 7th Month and C =12th Day (Hex). I assume they started with a year epoch of 2010.
I suppose to be absolutely correct, I considered each digit to be an ICOSIDIDECIMAL value ?
 
Just when everything was looking good ... we have a problem!

1609967834606.png

One of the Cell Voltages (#2) went crazy. Had been charging happily as a 4S pack. At 7am this morning Cell #2 started to increase rapidly in and charging was ceased at 7:32am voltage when it reached 3.9V.

I'm hopeful that this is just a balance problem and Cell 2 was at a higher SOC compared to the other cells. Please tell me if I'm dreaming???
Maybe I need to do a slow parallel charge of all cells before hooking them up in series?

Any advice would be much appreciated. Thanks.
 
The vast majority of charging occurs at or under 3.4V. Most cells are received with 50% charge. Charging @ 20A for 7 hours should be the max.

My biggest concern is that your charging system allowed such a spike. It should have terminated at 3.65V.
 
The vast majority of charging occurs at or under 3.4V. Most cells are received with 50% charge. Charging @ 20A for 7 hours should be the max.
Actually that's almost exactly how much charge occurred before this incident occurred.

My biggest concern is that your charging system allowed such a spike. It should have terminated at 3.65V.
I understand your concern! I set the BMS disconnector deliberately at 3.9V as a fail-safe as this is a test system and I am learning! The alarms started going when the out-of-balance was detected but the Victron Cerbo/Multiplus did not automatically stop the charging, so that's something I need to investigate. I let it run up to 3.9V in the hope that the Victron system would react, it didn't so I cut it manually, hopefully without too much damage to cell #2 at 3.9V.

I will now bring the other 3 cells up to a full charge (slowly!) with a 3.65V DC source. Then ... hmmm.
 
Just when everything was looking good ... we have a problem!

View attachment 32360

One of the Cell Voltages (#2) went crazy. Had been charging happily as a 4S pack. At 7am this morning Cell #2 started to increase rapidly in and charging was ceased at 7:32am voltage when it reached 3.9V.

I'm hopeful that this is just a balance problem and Cell 2 was at a higher SOC compared to the other cells. Please tell me if I'm dreaming???
Maybe I need to do a slow parallel charge of all cells before hooking them up in series?

Any advice would be much appreciated. Thanks.
Looks like you are charging your 4S pack (in series). Your first post said you were going to top-balance first (meaning charging to 3.65V in parallel) - did you do that?
 
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fafrd,
I started to do that, but my 3.65v supply is very low current. So slow ... All the voltages were so close ... so I decided to speed up the process buy hooking up to my 20A Victron Charger. Did I stuff up by getting too far ahead of myself??
 
fafrd,
I started to do that, but my 3.65v supply is very low current. So slow ... All the voltages were so close ... so I decided to speed up the process buy hooking up to my 20A Victron Charger. Did I stuff up by getting too far ahead of myself??
Yes. Your cells are probably fine. Spend the time to get them properly top-balanced and you will almost-certainly have a much better experience the first time you series charge (after series-discharging).

Some member spend literally months top-balancing their new cells.
 
Ok, will do. And I've noted that a series discharge should be carried out before the first series charge. What's the theory behind that strategy?

Thank you for your great advice.
Regards,
Mr Impatient ?
 
fafrd,
I started to do that, but my 3.65v supply is very low current. So slow ... All the voltages were so close ... so I decided to speed up the process buy hooking up to my 20A Victron Charger. Did I stuff up by getting too far ahead of myself??
You are learning a lesson that many people have learned:
1. unbalanced cells
2. charged in series
3. without automated protection
4. may look fine at mid SOC
5. but can go screwy rapidly towards the top or bottom

I set the BMS disconnector deliberately at 3.9V as a fail-safe as this is a test system and I am learning! The alarms started going when the out-of-balance was detected but the Victron Cerbo/Multiplus did not automatically stop the charging, so that's something I need to investigate. I let it run up to 3.9V in the hope that the Victron system would react, it didn't so I cut it manually, hopefully without too much damage to cell #2 at 3.9V.
Some notes for the future.
Your charger didn't react because it probably did not know it needed to. A BMS handles cell level safety, a charger is only aware of pack level voltage, and because your pack has not been balanced pack level voltage will not necessarily reflect cell level voltage (as you experienced). Even with a balanced pack, pack level voltage should not be assumed to be an accurate proxy for cell level voltage. As an example cell voltages of [4V + 3.5V + 3.5V + 3.5V] /4 = 3.625V avg, which is a safe voltage as far as the charger is concerned, since it can only see the total pack level, not individual cell voltages.

As a general pointer, patience and/or extreme attentiveness are the best approach to top balancing. Most of the issues we see here, come from people trying to speed the process up (either by an unprotected series charge or setting the voltage too high and not actively monitoring with a parallel charge).

The good news is, you caught it at 3.9, and a single cell exceeding 3.9 for a few minutes is probably not a huge deal in the realm of things.

From what I have observed, people that follow these three guidelines (and one honorable mention) have to work a lot harder to damage a cell:
  1. Never charge in series without a working BMS
  2. Never set your power supply above ~3.65 or 3.70 when charging in parallel
  3. Know how your power supply works, and set the voltage before connecting the cells
  • Honorable mention: Be present and attentive when charging in parallel above ~3.45 or 3.5 or so
Follow these 3 (well 4) guidelines and chances of damage are very small. More experienced or less cautious folks will sometimes not follow #2, I'm not saying its wrong to do so, just that it increases risk that could be easily avoided. What I am saying is for everyone, but especially beginners, following these guidelines significantly reduces the chances of error or damage (at the expense of a little extra time and effort). My anecdotal observation is that almost every problem with top balancing I have seen on the forum has been partially or fully explained by one of these 4 factors.
 
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Ok, will do. And I've noted that a series discharge should be carried out before the first series charge. What's the theory behind that strategy?
I've never heard, anything exactly to that effect, I think probably what @fafrd is saying is that you should top balance in parallel first, since a top balance is a parallel charge, you will need to discharge before your first series charge. The important part is not how you discharge, its that you have top balanced your cells.

Hopefully I am not misunderstanding or misquouting.
 
I've never heard, anything exactly to that effect, I think probably what @fafrd is saying is that you should top balance in parallel first, since a top balance is a parallel charge, you will need to discharge before your first series charge. The important part is not how you discharge, its that you have top balanced your cells.

Hopefully I am not misunderstanding or misquouting.
Exactly right. Performing your first series charge after your parallel balance is next to pointless and win’t tell you much of anything.

After assembling your parallel top-balanced cells into a series battery, what you care about is whether they Series-charge back up to the same voltages after being discharged in series.

If so, you are off to the races and your top-balance was successful.

If not, you’ve still got more work to do (or a problem cell).
 
Thank you fafrd & Dzl
Your advice is really valuable and much appreciated. I now have a much clearer idea of how I need to proceed.

The one thing that continues to perplex me is why the charge was not truncated when the BMS raised the out-of-balance alarm. I have the REC BMS which is integrated with the Victron Cerbo GX via CAN Bus. I thought that this architecture should provide a means to truncate charging based on cell out of balance rather than just pack voltage. Could I be mistaken? I'm really hoping that the problem is that I have just not configured it correctly. I chose the REC BMS because of the CAN BUS integration so that I don't have to rely on HV disconnect to truncate charge. I wanted HV disconnect to be used in an error condition only rather than for routine charging control.

I guess this is pretty equipment specific, I might need to ask some questions on the Victron forum.
Thanks again.
 
I chose the REC BMS because of the CAN BUS integration so that I don't have to rely on HV disconnect to truncate charge. I wanted HV disconnect to be used in an error condition only rather than for routine charging control.

In the future I think you should not be testing advanced features like this (1) before balancing (2) at such a high voltage. I think its important to verify protection features prior to charging to the limits.

This is actually something we probably don't focus on enough, we talk a lot about top balancing, about capacity testing, but we don't directly talk about testing and verifying your equipment works as expected, and verifying you know how to use it first. Being a relative newcomer to electronics, this is something that causes me anxiety personally, the knowledge of how limited my own knowledge and experience is :)

Thank you fafrd & Dzl
Your advice is really valuable and much appreciated. I now have a much clearer idea of how I need to proceed.

The one thing that continues to perplex me is why the charge was not truncated when the BMS raised the out-of-balance alarm. I have the REC BMS which is integrated with the Victron Cerbo GX via CAN Bus. I thought that this architecture should provide a means to truncate charging based on cell out of balance rather than just pack voltage.
The REC BMS is a high quality, advanced BMS. I don't have experience with it, but I believe it can do what you want it to do. The more advanced configuration and possibly more advanced control logic has more chances to mis-configure something I would assume.

I suspect the problem lies here:
I'm really hoping that the problem is that I have just not configured it correctly.
I don't know enough about the REC BMS or about your setup to really know though.

I was under the impression you set the BMS to cutoff at 3.9V, did it cutoff or did you do that manually or did it only alert you but not disconnect?
Did you have to do any manual config to get the Canbus control working and have you tested to make sure it works, prior to this test?

I guess this is pretty equipment specific, I might need to ask some questions on the Victron forum.
Thanks again.
Yeah, unfortunately once you start getting into device--device communication with more advanced components its hard to get or give general advice. Reaching out to REC or Victron or both for some direction (or at least reading the documentation) is probably your best bet for specifics. Until you get it all sorted no more testing at 3.9V ;)
 
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In the future I think you should not be testing advanced features like this (1) before balancing (2) at such a high voltage. I think its important to verify protection features prior to charging to the limits.


This is actually something we probably don't focus on enough, we talk a lot about top balancing, about capacity testing, but we don't directly talk about testing and verifying your equipment works as expected, and verifying you know how to use it first. Being a relative newcomer to electronics, this is something that causes me anxiety personally, the knowledge of how limited my own knowledge and experience is :)


The REC BMS is a reputable quality, advanced BMS. I don't have experience with it, but I believe it can do what you want it to do. The more advanced configuration and possibly more advanced control logic has more chances to mis-configure something I would assume.
Couldn't agree more about verification, and that's why I am going through this learning process before building the real system for my boat. I was impatient and was trying to balance and verify simultaneously. Part of the reason for my impatience is that I've had the BMS on my bench for some weeks but it won't even power up without a 4S battery, so I was unable to verify any of the advertised features until my cells arrived.
I was untrusting of the system, and therefore was monitoring closely.

I was under the impression you set the BMS to cutoff at 3.9V, did it cutoff or did you do that manually or did it only alert you but not disconnect?
Did you have to do any manual config to get the Canbus control working and have you tested to make sure it works, prior to this test?
I hit the kill switch on the inverter as the voltage reached 3.9V. I wasn't prepared to wait and see if the BMS did its disconnect thing as everything was beeping and I could see the voltage ramping up. The BMS operation in HV disconnect is simple and well understood, but as yet, unverified.
I did configure the CAN bus and it was clearly communicating with the Victron system. I need to investigate the operation of the Victron + BMS system further, but I need a working 4S battery do start doing that! Did I mention that I'm impatient ;)

Yeah, unfortunately once you start getting into device--device communication with more advanced components its hard to get or give general advice. Reaching out to REC or Victron or both (or at least reading the documentation) is probably your best bet for specifics. Until you get it all sorted no more testing at 3.9V ;)
The Victron documentation is extensive, but not at all cohesive. They are developing lots of new features and products very quickly while deprecating others, so its a bit of a challenge wading through it, but I'll get there more easily once I have the system in place to test properly.
The REC documentation is minimalist, and is written by someone with English as a second language, so I've asked them a lot of questions already!
My first BMS setting change when the 4S battery is serviceable will be to move that 3.9V cut-off down to 3.7V for testing.
 
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Actually that's almost exactly how much charge occurred before this incident occurred.


I understand your concern! I set the BMS disconnector deliberately at 3.9V as a fail-safe as this is a test system and I am learning! The alarms started going when the out-of-balance was detected but the Victron Cerbo/Multiplus did not automatically stop the charging, so that's something I need to investigate. I let it run up to 3.9V in the hope that the Victron system would react, it didn't so I cut it manually, hopefully without too much damage to cell #2 at 3.9V.

I will now bring the other 3 cells up to a full charge (slowly!) with a 3.65V DC source. Then ... hmmm.

Always best to test where it's safer. If it will work at 3.65, it will work at 3.9. Unlikely you did any damage at all.
 
I just finished a capacity test of my LF280 Eve Cells using a 0.1C discharge.
I have now managed to get my REC BMS/Victron CerboGX to control the charge/discharge cycles using DVCC, and have set the main contactor to disconnect just outside these limits at 2.9V and 3.7V.

So I charged the bank fully in parallel to 3.65V and allowed it to stand overnight connected in parallel. This morning it was sitting at 3.55V, and I then reconfigured it as a 4S battery. I then set up a fixed load on the invertor corresponding to 28A current drain from the battery. This increased very gradually to about 30A towards the end of the 10 hour long test as the voltage sagged.

The measured capacity was 282Ah, and I am very happy with that. These cells get a tick from me.

It's good to see the shape of the discharge curve matches the discharge curve given in the EVE's LF280 Specification.

LF280 Discharge vs Rate.jpgLF280 Discharge Test.jpg
 
Congrats Mariner62. The LF280N image looks like none of the tests made it to 280Ah. They are about 270Ah to 280Ah and that was a brand new cell.
 
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