EVE LF280K mit 6000 Zyklen oder EVE LF304 mit 3500 Zyklen?
6000 Zyklen, bei einem Zyklus pro Tag... das sind 16,5 Jahre Experimente !!!!
Sie hätten 2006 beginnen sollen :crazy: ,
gab es damals schon die prismatische Alu-Zelle und den Lifepo4?
16,5 JAHRE ... dank der Komprimierung der Zellen, für eine Garantie von ... ?
Die Frage, die ich in diesem Forum viewtopic.php?f=7&t=1760 gestellt habe und die noch nicht beantwortet wurde, ist folgende: Ohne die Wichtigkeit und Notwendigkeit zu leugnen, das Aufblasen der Zellen aus statischen Gründen und wegen möglicher chemischer Starifikationen im Inneren der Zelle durch eine Kompression zu vermeiden, soll EVE Tests mit diesen Zellen durchgeführt haben.
Gut, aber es wurden keine scheinbaren Testprotokolle erstellt?
Es kann sich also nur um eine statistische Extrapolation handeln.... auf welcher Grundlage?
Wir haben den Lebenszyklus der Zellen verdoppelt ... durch statistische Extrapolation ...
das ist sehr stark oder man musste es wagen!
Ich wage hier zu behaupten, dass ein so wichtiger technologischer Durchbruch wie dieser "Verdoppelung der Zyklen/80%" in der Lifepo4-Welt für viel Aufsehen gesorgt hätte und in wissenschaftlichen Publikationen mit Peer-Review-Verfahren anerkannt worden wäre...
EVE würde mit diesem Durchbruch alle Konkurrenten in den Schatten stellen...
Die Frage, die sich stellt: Lohnt es sich, mehr für eine 280Ah-Zelle zu bezahlen, die weniger Kapazität hat als eine 304Ah-Zelle desselben Herstellers, für eine hypothetische Verdoppelung der Zykluszeit, die nicht durch ein strenges Protokoll nachgewiesen werden kann und nicht offiziell nachgewiesen wurde?
Ist mir da etwas entgangen?
sonnige Grüße
NB: Im Gegensatz dazu wurde kürzlich in der Zeitschrift Nature eine, sagen wir, "seriösere" Studie über Lithiumbatterien veröffentlicht, in der postuliert wird, dass eine starke Entladung nach dem Ende des Ladevorgangs eine höhere Gesamtkapazität erreicht und aufrechterhält, und zwar durch den Zerfall von Klumpen von Lithiummolekülen, die sich im Laufe der Lebensdauer dieser Art von Batterien bilden.
Ich habe nur das Abstract gelesen, aber es wäre schade, wenn Sie die Gelegenheit für einige Manipulationen bei der Wartung verpassen würden!
https://www.nature.com/articles/s41586-021-04168-w (kostenpflichtiger Zugang).
die 6000 zyklen wurden mit 0,5c angegeben die anderen zellen werden mit 1c angegeben deswegen der unterschied
Ja, aber wie rechtfertigen Sie die 6000 Zyklen im Laufe der Zeit?
Statistische Extrapolation kann man nicht leugnen!
Das klingt nach Marketing...
xxx
Meines Wissens gibt es außer den "großen" Großhändlern nur zwei Händler, die direkten Zugang zur EVE-Fabrik mit gepaarten Zellen und den Testbögen mit QR-Nr. der Fabrik haben, von denen ich ein Muster beilege.
Wenn ein Händler nicht in der Lage ist, diese Tests spontan zu produzieren, sollte er sich vielleicht von ihm fernhalten.
https://szluyuan.en.alibaba.com/?spm=a2700.12243863.0.0.b6173e5fyuADaw
https://www.docanpower.com/index.php?route=common/home
Noch zwei Datenblätter, die interessant sein könnten:
-1 ) wie man die QRcodes der Zellen entschlüsselt
16451=3501-How-to-Distinguish-Grade-A-and-Grade-B-in-LiFePO4-Prismatic-Cell.pdf|attachment (400 KB)
16451=3500-Quickly-Identify-Fake-Lifepo4-Battery-Cells–QR-Code.pdf|attachment (233 KB)
-2 ) ein kleines Vademecum, das zwar primär ist, Ihnen aber einen kleinen Einblick in die Fälschungen von Zellen gibt.
You may have noticed that almost every LiFePO4 battery cell has a QR code on it.
What is the LiFePO4 QR code?
The QR code is generated by a combination of characters that represent
information about the LFP battery cell. This is shown in the picture below(Notice
where it is on the battery).
Using QR code parsing software (you can do this with your phone’s QR code
parsing app), you will get this string of battery information. Some manufacturers
will inscribe this string of characters next to the QR code, such as EVE.
Actually the string parsed by QR code is this horizontal and vertical string
engraved next to the QR code.
How to parse the QR code information?
You can parse the QR code by reading the description of it in the specification.
Let’s take the QR code of EVE 3.2V 280Ah LF280K as an example to explain the
process of parsing the LiFePO4 battery cell information.
We read out the string of this battery as 04QCB76717900JB5S0005806.
According to the encoding rules, we can get the following information.
Vendor Code: EVE
Production Type: Cell
Cell Type: LiFePO4
Model: LF280K
Production Line: 71
Task Code: 79
Factory Address: Jingmen
Production Date: May 29th 2021
Product Serial No.: 5806
In fact, for the buyer, only the production date needs to be concerned. So let’s
focus on describing the parsing rules of date code.
The date of manufacture is the 15th, 16th and 17th characters, which correspond
to the year, month and day respectively.
In this case it is B5S.
Year: 1~9 represents 2011-2019, the next years are in alphabetical order A~Z, A
represents 2002, B represents 2021…
Month: 1~9 represents January to September, A~C represents October to
December.
Day: 1~9 for the 1st to the 9th, A~V for the 10th to the 31st.
So B5S represents the production date of May 29th, 2021.
How to use QR Code to avoid buying fake battery
cells?
Suggested steps:
1, Ask the seller for a photo of the QR code of the battery cell
before purchase.
Sellers of A-grade battery cells are happy to provide this information if they are.
2, parse the date of manufacture.
Production dates preferably within a year to avoid buying old stock.
3, Check whether the QR code is in the right place.
The QR code of A-grade cells is always in the position marked on the
Specification.
The QR code of B-grade battery has only a smaller QR code in different
position with a different coding rule. The original large QR code will be
scraped
The QR code for fake batteries is elsewhere and does not parsing any
information or points to a strange URL. Some fake batteries have QR
codes that are printed with white paint rather than laser engraved.
In short, the QR code for LiFePO4 battery cell is its identification, which allows you
to know the production information about the battery before you buy it.
How to Distinguish Grade A and Grade B in
LiFePO4 Prismatic Cell?
We all know that Grade A cells are much more expensive than Grade B
cells.So if you want to compare two products, you need to make sure that
they are at the same level.
The best way to know a cell is Grade A or Grade B is to check if the cell
meets the manufacturers' specifications.Today, we are going to talk about
some important parameters listed on the datasheet.By compare the data
with the specification to distinguish Grade A and Grade B cells.Let' s
check.
1. AppearanceAppearance
Each cell will be produced with an unique QR code as a proof of
Each cell will be produced with an unique QR code as a proof of identity.Which make it more convenient to be recognized for the identity.Which make it more convenient to be recognized for the manufacturers wmanufacturers when offering afterhen offering after--sale services.And as we mentioned in sale services.And as we mentioned in the last post, Grade B cells are categorized as unqualified ones, they the last post, Grade B cells are categorized as unqualified ones, they usually do not offer warranty.Manufacturers will scrape off this QR code usually do not offer warranty.Manufacturers will scrape off this QR code for distinguishing.So if you find a battery cell that wifor distinguishing.So if you find a battery cell that with QR code th QR code concealed.Mostly it is Grade B cells.However, all Grade B cells will be concealed.Mostly it is Grade B cells.However, all Grade B cells will be covered with a new insulating sheet.So if there' s no obvious signs of QR covered with a new insulating sheet.So if there' s no obvious signs of QR code outside, you' Il need tocode outside, you' Il need to tear off the insulating sheet.tear off the insulating sheet.
Tips: It does not mean that cells c
Tips: It does not mean that cells come with QR code are all Grade A cells.ome with QR code are all Grade A cells.
2.Dimension & Weight
2.Dimension & Weight
As dimension&weight will be slightly different at different SOC state, it
As dimension&weight will be slightly different at different SOC state, it would be necessary for you to confirm the testing SOC state with would be necessary for you to confirm the testing SOC state with suppliers.Then measure the size at the same SOC conditiosuppliers.Then measure the size at the same SOC conditions.And ns.And compare the resultscompare the results with listed on the date sheet.with listed on the date sheet.
So follow the datasheet SOC statement, and measure the dimension and
So follow the datasheet SOC statement, and measure the dimension and weight of cells. If the size meets the datasheet, it is ok. If the size does not weight of cells. If the size meets the datasheet, it is ok. If the size does not following the datasheet, then maybe problem or following the datasheet, then maybe problem or grade B cells.grade B cells.
3.Capacity
3.Capacity
Capacity is usually tested at the temperature of 25°C, charging and
Capacity is usually tested at the temperature of 25°C, charging and discharging rate of 1C.Record the real tested capacity value.And compare discharging rate of 1C.Record the real tested capacity value.And compare the rthe results with the specifications.esults with the specifications.
Tips: Different temperature will affect the
Tips: Different temperature will affect the capacity of lifepo4 cells. So capacity of lifepo4 cells. So some manufacturers will send you the cells that the capacity is a little bit some manufacturers will send you the cells that the capacity is a little bit higher than claimed. If your testing results is a little bit higher than the higher than claimed. If your testing results is a little bit higher than the datasheet. That will be alright.datasheet. That will be alright.
4.Internal Resistance
4.Internal Resistance
First check the
First check the testing conditions on the datasheet, or confirm that with testing conditions on the datasheet, or confirm that with suppliers. That is the temperature and SOC state. Most manufacturers test suppliers. That is the temperature and SOC state. Most manufacturers test AC internal resistance at 1000Hz. Other manufacturers, however, will test AC internal resistance at 1000Hz. Other manufacturers, however, will test
the DC internal resistance. Generally speaking, th
the DC internal resistance. Generally speaking, the DC internal resistance e DC internal resistance is more reliable.is more reliable.
If your testing results meet the datasheet, It is Grade A cell.
If your testing results meet the datasheet, It is Grade A cell.
5.Self
5.Self--Discharging RateDischarging Rate
The self
The self--discharging rate is calculted according to voltage decreasing. discharging rate is calculted according to voltage decreasing. And at different SOC state, the selfAnd at different SOC state, the self--discharging rdischarging rate may be different. At ate may be different. At the 100% SOC state, the voltage will decrease quicker than at 50% SOC the 100% SOC state, the voltage will decrease quicker than at 50% SOC state.So check the datasheet to make sure the testing SOC state fisrt.state.So check the datasheet to make sure the testing SOC state fisrt.
Testing Methods
Testing Methods
Solution 1: to test the voltage decreasing rate at room temperature of 25
Solution 1: to test the voltage decreasing rate at room temperature of 25℃℃ by stocking for 28 days.by stocking for 28 days.
Solution 2: to test the voltage decreasing rate at higher temperature of 45
Solution 2: to test the voltage decreasing rate at higher temperature of 45℃℃ by stocking for 7 days.by stocking for 7 days.
If the self
If the self--discharging rate is 3%discharging rate is 3%
For normal temperature, the self
For normal temperature, the self--discharging rate per day is discharging rate per day is 0.03/28=0.03/28=0.00107.then it's about 0.00107.then it's about 0.107%.0.107%.
For high temperature, the self
For high temperature, the self--discharging rate per day is 0.03/7=discharging rate per day is 0.03/7=0.00428, 0.00428, then it's about 0.43%.then it's about 0.43%.
So we can stock the cells in the specified testing conditions, check and
So we can stock the cells in the specified testing conditions, check and write down the voltage decreasing of the cell each day. Then, you can write down the voltage decreasing of the cell each day. Then, you can check echeck each days' s selfach days' s self--discharging rate and the month/week's discharging rate and the month/week's selfself--discharging rate as a double check.Generally speaking, solution 1 of discharging rate as a double check.Generally speaking, solution 1 of stock for 28 days are more reliable.stock for 28 days are more reliable.
6.Capacity Recovery
6.Capacity Recovery
To test the capacity recovery rate, you just do a 100% DOD charging
To test the capacity recovery rate, you just do a 100% DOD charging and and discharging cycle. And check if the capacity recdischarging cycle. And check if the capacity recovery rate meets the overy rate meets the datasheet.datasheet.
For example, for a 3.2v 100ah battery cell, if the recovery rate is 95%.
For example, for a 3.2v 100ah battery cell, if the recovery rate is 95%. We have tested the capacity at the beginning. It is 100ah. Then after all We have tested the capacity at the beginning. It is 100ah. Then after all the test, we do a 100% DOthe test, we do a 100% DOD charging and discharging. Then the capacity D charging and discharging. Then the capacity should be more than 95ah. If yes, the battery capacity recovery rate meets should be more than 95ah. If yes, the battery capacity recovery rate meets the datasheet. It's Grade A quality cell.the datasheet. It's Grade A quality cell.
Conclusion
Conclusion
What we are doing is to compare the testing data with specification of the
What we are doing is to compare the testing data with specification of the
cells.
cells. So we can trust the datasheet or supplier.After all the tests and So we can trust the datasheet or supplier.After all the tests and comparison, if all the data meet the specification or datasheet, it is grade comparison, if all the data meet the specification or datasheet, it is grade A cells. If not, it is grade B cells.A cells. If not, it is grade B cells.
One more question:
One more question:
If you've picked out several manufacturers who
If you've picked out several manufacturers who provides Grade A cells, provides Grade A cells, which one you should choose? Just consider the price differences?which one you should choose? Just consider the price differences?
Bitte entschuldigen Sie, dass ich die Bilder nicht weiterleiten kann!
xxx