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Disappointing EVE 280K Results

I think I'm not getting correctly your proposal for the formation process. Can you, please, give your recommendation for the proper process for commissioning 300Ah cells?

How many charge/discharge cycles at what rate? Cause if we are talking about 0.1C - this is doable. If the formation is expected at 0.5C - this gets complex and expensive for large capacity cells.
 
After my experience with the "Michael Group Buy" debacle (and I know even the mention of it still gives some members cold sweats and can get you canceled) ... But after that deal, packaging is king. If I get 95+%, I'm pretty happy. Docan China far EXCEEDED that expectation.
 
I think I'm not getting correctly your proposal for the formation process. Can you, please, give your recommendation for the proper process for commissioning 300Ah cells?

Sure. Do the typical .2C or less cycle at least 5 times. Just to make sure everything is set up *in case* your manufacturer rushed things.

Now hit it up at .5C or more. One or two cycles. If you don't have a .5C charger, then consider using multiple sources, such as using a charger along with your solar array:


If the formation is expected at 0.5C - this gets complex and expensive for large capacity cells.

That's ok - this is returning back to the question of those who are crying over losing 5% from faceplate ratings. Doing this might get some of that back because the entire surface is now reacting all the same when put back into a lower draw application.

Unrelated chemistry, but it is well known that pure-lead batteries if treated like little babies, lose capacity. Enersys usually specs about 0.3C minimum to maintain their published cycle life specs as an example. Some purchasers bought into the huge batteries, and then tried to use their 1a battery tender to charge and cried about the capacity test. :)
 
I'm not going with a 1A charger, but 150A (0.5C) charging current is quite a challenge. My battery inverter is 75A max. The next "nice toy" I have is 24A max.

The battery inverter and the 24A toy will get me somewhere between 0.3C - 0.35C. Anything over that and I'll need more expensive toys.

The more I think about it, the more I'm considering the single 300Ah battery as a mistake. I should have gone with 48V 100A batteries in parallel.
 
but 150A (0.5C) charging current is quite a challenge
Right? I have two 80A charge controllers (max output 4800W), each with 6000W+ of panels and I'm lucky to get 130A into the batteries on a cracker day, once I subtract the loads that are also being powered. 130A sounds like a reasonable amount but over 4x 280Ah batteries that's only ~30A into each battery :(
 
If you have 4 batteries in parallel - disconnect 3 of them. 130A is pretty close to 0.5C.

I'm not doing this 0.5C charging, as the cost for the equipment will be close to $1000. I'll let the inverter load it as much as it can (around 75A) and add an additional 24A with the RD6024 power supply (if I manage to find a suitable power supply for it).
 
You agree on something.
You pay the price in full.
You receive a portion of what has been agreed.
Until new agreement is achieved, someone should be pi$$ed...
I agree it's a slippy slope if you don't draw the line somewhere and sellers see no consequences for their actions then anything goes from then on. CeCe should get a partial refund for sure and Jenny Wu should reply back with an apology and be committed to delivering what she promised regardless.
Quote:
Another BB consumer. Good luck and be well.
"Gray market", 'aftermarket', call 'em whatever you want - they're CHEAP. Enjoy or not, nobody is being 'ripped off'. This thread is a joke...I'm out. ?
End Quote
Browneye with a picture of a white man with blue eyes?
He sounds like a chinese seller with invested interests posing as a white American Buyer
I'm considering Cancelling my order with Jenny Wu after Browneye's comment Does anyone think I'm overreacting?
 
I wanted to share my recent (September 2022) disappointing experience buying prismatic cells to the forum. My plan was to buy a small group of prismatic cells (20 cells) and test them before committing to several larger purchases based on the results of the test.

I first did a bit of research on LiFePO4 cells and purchased some test equipment and went on a hunt for a supplier. To keep the total battery cost per Ah lower I planned to use cells in the 280-300 Ah range.

Based on nothing much more than comments in the forum, YouTube videos and email replies from some of the suppliers I decided to use Docan and worked with Jenny Wu. I will try to rank each part of the experience on a 1 to 10 scale.

  • Jenny Wu was very quick to respond to all my initial questions about the cells they have in stock. I could send Jenny Wu a question and within a few hours I would receive a reply along with the “are you ready to order” at the bottom of the email. A mark of a good sales person who is always trying to close that sale. Jenny seemed knowledgeable about their products and answered “most” of my questions about the cells very quickly. Often within a few hours.
  • After many emails describing the cell specifications, when they were manufactured, condition, capacity, shipping, and billing and what the supplier would do if there are problems with the cells (the replies to testing questions were rather vague) I decided on the EVE 280K cells. Then we discussed prices shipped from China vs shipped from Houston and I elected to pick them up at the Houston warehouse.
  • New 280 Ah cells and I can get them within a few days of ordering the cells. The price is a bit higher than other suppliers but other than that this seems like a reasonable deal. Due to a few of Jenny Wu’s answers being vague there are a few points off. (8/10)

  • The actual purchase of the cells went very smoothly. (10/10)

  • Setting up the pickup time was just a simple phone call and the people working at the warehouse were very friendly and helpful when I picked up the cells. (9/10)

  • The cells are packaged very well and it is doubtful even the most careless delivery driver could damage them in shipment. (10/10)

  • Once I had them back home a quick visual inspection of the of the cells showed them to be in very good condition. No bloating and with just a few visual blemishes. Not pristine but very good. (9/10)

  • In the next step the QR Codes were checked to validate the cells were made in December 2021. Some were and some in January 2022 and some in February 2022. Only a few of the cells were made on the same day and those were in different boxes. This was a concern since I expected new cells to all be from one batch so I ask Jenny Wu if it was normal to have so many different manufacturing dates and mentioned my concern. After numerous emails asking this question, I am still waiting for an answer. At this point I must assume Jenny Wu is not planning to answer.
  • My thought is that cells made in the same batch are going to match each other much better than cells from random batches. So for mismatched cells and poor customer service. (2/10)

  • The voltage and IR of the cells were checked. The voltage ranged from 3.2861-3.2951 V and the IR 0.18-0.20 mΩ. This seemed within specification from the EVE product specification sheet. (10/10)

  • The cells were charged to full capacity using the specifications from EVE Power Product Specifications for LF280K cells. They specify a charge rate of 0.5C at a voltage of 3.65 volts and a cut off change rate of 0.05 C. I could only charge at 40 Ah but I did use 3.65 volts as the voltage maximum and stopped charging at 0.05 C or 14Ah. The room temperature is 23-24C.
  • All of the cells required ~180 Ah to fully charge and were shipped at a 34-36% SOC. No dead cells and nothing with a high SOC and none of the cells showed any swelling when charged to 100% SOC so a (10/10).

  • The test conditions in the Eve Product Specifications were used as much as possible. Temperature 23-24C. After charging the cells to 3.65 V they sit for 60-90 minutes before the discharge test begins. A ZKETECH battery tester is used at 35Ah (0.125C) until the cell voltage is 2.8 V. At approximately one hour into the test the terminal temperatures are checked (23-24C). After the discharge test I either recharge to about 35% SOC or fully recharge if I plan to do a second test.
  • Since my early results were coming back low (263-275) I contacted Jenny Wu and other than one message claiming “The Battery Test Factory uses 30Ah” they never sent or said anything more. So, between the low test results and no response from the supplier. (1/10)
As a follow up to the 30Ah claim 3 cells were tested at 35Ah and then at 30Ah. The results of the test were all within a maximum 0.4 Ah of each other. I also retested 3 cells using a cut-off of 2.5V vs the 2.8V. Using 2.5V cut-off voltage resulted in 2.4- 2.8 extra Ah of capacity.

To be fair one cell did meet the 280Ah capacity test. It tested at 285.8Ah and a repeat test on that cell was nearly identical at 285.6Ah. Another interesting note is the few cells that were from the same batch all tested nearly identical capacities.

Overall… I am disappointed with the cells performance from Jenny Wu but more importantly I am disappointed in how the supplier handles problems. Before the cells were purchased we covered testing and performance. I did not expect a refund but did expect more than being ghosted by the supplier. So was I ripped off. Yes, I feel I was... My thought is even if it is a reasonable price if the supplier sells you 280Ah cells and you don’t get 280Ah cells then you were ripped off. It is just a question of how badly you were ripped off. As it is I can build a 263Ah battery from these cells and start looking for a new supplier.
 
Browneye with a picture of a white man with blue eyes?

Brown (color) eye (singular)

What do you think he's talking about now?

(I conclude he's referring to a butthole to be funny because I'm immature)

He sounds like a chinese seller with invested interests posing as a white American Buyer

If you were more than a few days old, and you bothered to read some of his 1400+ posts, there's no possible way you could form that opinion. Shills get booted from here FAST.

I'm considering Cancelling my order with Jenny Wu after Browneye's comment Does anyone think I'm overreacting?

Overwhelmingly.

I don't want to tarnish someone's name unfairly and I will test the cells and let everyone know the results good or bad when I get them.

Please and thank you.
 
I agree it's a slippy slope if you don't draw the line somewhere and sellers see no consequences for their actions then anything goes from then on. CeCe should get a partial refund for sure and Jenny Wu should reply back with an apology and be committed to delivering what she promised regardless.
Quote:
Another BB consumer. Good luck and be well.
"Gray market", 'aftermarket', call 'em whatever you want - they're CHEAP. Enjoy or not, nobody is being 'ripped off'. This thread is a joke...I'm out. ?
End Quote
Browneye with a picture of a white man with blue eyes?
He sounds like a chinese seller with invested interests posing as a white American Buyer
I'm considering Cancelling my order with Jenny Wu after Browneye's comment Does anyone think I'm overreacting?

This is what happens when you cheerlead or cheerbash, eventually it will come to bite you in the rear.

This is why everyone should stick to facts & numbers.

That being said the grade A 280K with test report isn't all that great TBH...
 

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