diy solar

diy solar

2nd Buy from Amy Wan/Luyuan

S Davis said:
I understand, what I was getting at is the difference between your number and the report(305.6 and 313ah) could be because of different testing temperatures. I see people test all the time in unconditioned spaces and they don’t think about the cell temperature affecting their results. Here is the rated discharge by temperature for the 304’s.

View attachment 205615
Click to expand...

It seems anything above or below 25°C is going to result in reduced capacity even if the cell temp inches up a few degrees. Based on impedance, I should have about 0.0042W of heating... :p
 
Decided to mix it up and speed things along. Whipped out the big guns... iCharger 4010 DUO.

70A charge and discharge using both channels on the same cell:

1711757704363.png

The 3.601/3.619V is the measurement at the leads influenced by the current.

The 3.376 is the OCV sensed by the balance leads.

I am able to specify a 14A tail current (0.05C) @ 3.65V with a 20 minute wait before a 70A discharge to 2.5V, so it will charge/discharge on its own without my intervention, and it might finish before I go to bed... :)
 
This charger inverts the current and capacity on discharge as (-) numbers.

70A to 2.5V, 300Ah:

1711811928042.png

For apples to apples with the first cell, I ran a 30A discharge to 2.5V after the 70A terminated, 6.1Ah:

1711812159176.png

306.1 total vs 312.4. 98%

Having broken out the beast, I'm probably going to test all as a cell can be fully tested in < 9 hours assuming I charge from the as-received condition.

I can automate the 30A results by tapering the discharge current from 70A to 30A once 2.5V is reached... like an UNabsorption phase... :)
 
DANG! 70A is suhwheeeeet...

I'm using the 70A to charge from the ~33% as received SoC and then discharge. Takes just under 8 hours to fully cycle a cell, and it's totally hands-free. To keep that one cycling, once discharged, it's onto the 30A charger for 3 hours to get exactly 90Ah in them.

Results have been wicked consistent.

305.6 - 30A to 2.5V
306.1 - this one is likely a little higher due to the two separate discharges (70A to 2.5V followed by 30A to 2.5V) with an extended rest in between.
305.7 - 70A to 2.5V, hold 2.5V and taper current to 30A

Confidence is up, so I'll be starting a cycle before bed. I'll be able to test two cells per day. Looks like I'll be testng all of them... :)
 
sunshine_eggo said:
Order paid for on 1/18/2024
Order shipped 2/28/2024 (was supposed to ship before Chinese new year - about 3 week slip
Click to expand...
My second order shipped out in four weeks vs 5 for you. Perhaps because I ordered at the very end of the Chinese New Year.
sunshine_eggo said:
Order shipped 2/28/2024 (was supposed to ship before Chinese new year - about 3 week slip)
Order received 3/25/2024
Click to expand...
I hope to have the order by the end of April and assembled a day or two later.
 
Have you tried lowering the discharge current even more <10a to see if you can get the test setup to produce the Ah values they provided?
 
740GLE said:
Have you tried lowering the discharge current even more <10a to see if you can get the test setup to produce the Ah values they provided?
Click to expand...

No. I shouldn't have to. Per the datasheet, the rating is based on a standard discharge of 0.5C to 2.5V following a standard charge of 3.65V to 0.05C tail current.

70A is 0.25C (and I'm tapering to 30A cut-off), so in reality, my numbers are likely even closer to 280 than they are to 313 when a standard discharge (140A) is conducted.

I'm basically measuring 0.1C discharge capacity.

Furthermore, I've acknowledged that my equipment correlates within about 1%, but what I didn't say is that the charger reports slightly higher than the other two references, so my numbers may be 0.5-1.0% optimistic driving actual values down closer to 280Ah.

Conclusion: The super fancy "EV-Grade-A" spreadsheet values are bullshit, but these are notably better than the last batch.

I'm still happy.
 
ArthurEld said:
Are you going to capacity test the assembled battery?
Click to expand...

Not in any serious way. Because I'm full of fuckwithery, I'll probably deliberately run it down to near empty as a pseudo-cap test.

The battery will perform as good as the weakest cell, so I'm pretty confident that I'll get at least 300Ah out of it as my typical usage will be about 10A.
 
I'm glad you are happy. For all of us that is the main objective.

Thank you as well for this thread. When I purchase cells I personally am looking at the stated capacity as the goal. The old tests performed by Will followed a similar approach and if the assembled battery met cell capacity (e.g. 280) then it was considered a success.

When I purchase a simple thing like an an apple, I don't care about service. It will fade from existence fairly quickly. When I purchase something like battery cells, a case, BMS or components then I prefer service. This is the main reason I went with Current Connected for my Victron equipment. They have developed an excellent reputation on this forum. I feel the same way about Amy. When I made a recent purchase, I bought 304 cells. They were presented as such. The EVE values were presented after the sale was made so I didn't perceive any attempt to persuade the decision. In fact, I purchased some grade B cells from Amy for another application. She was careful to indicate that these cells were actually below the stated values which was appreciated. I made the purchase in this case because the cells served a need.

Amy has always been available to answer support questions both before and after the purchase. She patiently answers my questions and if she doesn't have it immediately will take the time to find out for me. In a world where others have expressed frustration about support issues, I find this refreshing and the reason I personally continue to utilize her services.

I wanted to thank you for all of the support and assistance you provide on this forum. Your help has been appreciated by many including myself. I look forward to future threads where you continue to explore the many products that are being used by members. Hoping you have a great day!
 
Last edited:
sunshine_eggo said:
Not in any serious way. Because I'm full of fuckwithery, I'll probably deliberately run it down to near empty as a pseudo-cap test.

The battery will perform as good as the weakest cell, so I'm pretty confident that I'll get at least 300Ah out of it as my typical usage will be about 10A.
Click to expand...
do you have a link to "Amy Way @ Luyuan " that some one cand find their online store easy?
 
Stircrazy said:
so what does contacting her directly do for you? I just added 16 cells to an order on the web page and it was 111.00 cdn per cell plus 500 in shipping.
Click to expand...
Message her and find out.

When I contacted her on order #1, she gave me pricing less than on the website. I also got a slight discount for being a forum member. Also, any issues were explained to me, such as going to the size BMS I wanted versus what was listed on the sight.
 
You must log in or register to reply here.

Similar threads

S
Does Amy Wan of Shenzhen Luyuan stand behind her product?
2
Replies
24
Views
1K
Yurtdweller
Yurtdweller
J
JBD BMS: only 1 cell won't balance
Replies
10
Views
546
Alkaline
Alkaline
S
New battery from Amy Wan at Shenzhen Luyuan on Alibaba
Replies
2
Views
753
Skid
S
M
Buy now or wait? 48v battery build
2
Replies
25
Views
1K
mjgillen
M
C
Not getting the same capacity from the battery as from the cells
Replies
3
Views
356
Brucey
Brucey
Back
Top