New batts from Docan Tech

jimcalf

Solar Enthusiast
Joined
Aug 1, 2020
Messages
69
Location
Akron, OH
I just received 16 230h Eve LF230 batteries from Jenny Wu and Docan Technologies. These were ordered from China about Oct 21st, so they arrived via FedEx in about 9 weeks. I have to say, I'm impressed with the packaging and condition of the cells. The boxes were 100% wrapped in packing tape and the foam packaging inside provided excellent protection. All cells are pristine. No bloating at all. The QR codes are in the right place and perfect. It will take me a little time to top balance and run a full capacity test, but initially, all cells are at exactly 3.29V. Average weight was 9.192 lbs with a variability of 0.2%. So far, I am extremely pleased with buying from Jenny Wu and Docan Tech.

Battery Label.jpg
 

SunnyNM

New Member
Joined
Jan 30, 2022
Messages
16
Amy Zheng helped me out during Chinese New Year. I got my cells in today and all measured right at 3.404 for all 16. Beautiful packaging. One box had been abused some but the cells were well protected and had no damage. I ordered another 16 after seeing the condition of these.
 

michlamb

New Member
Joined
Feb 4, 2022
Messages
6
Bought some 100ah from Jenny Wu, Hope they work out. Will be top balancing and capacity testing.
 

BV2

Solar Enthusiast
Joined
Mar 7, 2022
Messages
10
I received my order from Amy Zheng today. Overall, I will say it was a good experience. it took 6 business days to receive my 8-230ah cells, from when I transferred Pay Pal money to their account in China. There are fees from Docan for using Pay Pal and also from Pay Pal to send money overseas. Amy's emails were prompt (once I accounted for the time difference and weekends) and polite. The cells all looked great and there was very little voltage variation from cell to cell. Docan provided what was advertised in a reasonable time and for a good price. No reason to not go direct through them. The savings more than paid for my new 200 amp BMS. BTW, I do appreciate US businesses and I'm willing to pay a few bux more when there is added value of having a middle man. However, I feel some companies add way more to the cost and do little to extra to make sure you are taken care of. Thanks, Will, for the referral.
 

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rickst29

Solar Addict
Joined
Mar 27, 2021
Messages
479
Location
Reno, NV
I received 4 cells, 230 Ah, from the USA warehouse yesterday. The battery cells are in great condition, shipped from Texas via UPS. They came with matching 6mm studs (with sufficient height to handle almost any busbar arrangement), matching bolts, and busbars which I feel to be inadequate.

In the first picture, I show the uncompressed battery pack being sort-of balanced by a 6A, 14.6v charger. (I adjusted the Daly BMS parameters with Sinoweath: I reduced the "full" cell voltage to 3.60v, reduced the minimum current sensitivity to 300mA, reduced the "balance start" voltage to 3.4v, and slightly increased the balancing current). It seems to be working well, as monitored by either Sinoweath or the Android App. (Cell Voltage differential is reading either .002 or .001, while pack voltage slowly increases.)

When my two steel compression plates arrive (tomorrow), I will be using 4x compression springs and 3/8 threaded rod to compress the pack, it needs a bit more than 600 lbs. But, when I do that reassembly, I will also preplace the bus bars. As show in the second picture, the supplied bus bars are each a pair of very thin "bars", held together with shrink wrap. The total thickness (both thin bars together) is perhaps 1.5mm, I didn't bother to measure it.

In contrast, the "proper" bus bars which I will install when I compress the pack have about 2-1/2 times that thickness. And of course, the supplied "thin ones" have 4 layers of plating between the two of them, while the "proper" bars are plated only on the outside. The copper cross-section of the good ones is roughly 3x greater.

I will SWAG the provided pairs to roughly similar to AWG-6 stranded wire, which starts to contribute significant voltage drop (via unwanted heat) at current above about 50A. In my 12v pack, there are 3 of these bus bars at roughly 2 inches each, all warming up the cells when I run the inverter with moderate loads. Thus my replacement. These "better" bars were designed for Eve 270A cells, and I will need to drill one new hole into each one at shorter length, fitting the 230A cells. They should be good for 3x the current.
 

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rickst29

Solar Addict
Joined
Mar 27, 2021
Messages
479
Location
Reno, NV
Good news with regard to those welded terminals (at least in the 230Ah version).

I've now tested with about battery load around 148A @ 12.7V, through an OK Inverter, driving a 1300 watt kitchen toaster at 120v. (That Inverter was only about 70% efficient, according to the Daly BMS current value. I did not have my fancy coulomb counter attached to obtain a more reliable number.) With my "stacked bus bars", the terminals did (12v negative ground, and bus bar terminals at higher voltages) did NOT become warm to touch during a 4 minutes test. I did not have a "handy" set of kitchen appliances to reach 200A on the terminals, and my results might have been different with such a test. I am also unsure whether resistive heat could have been drawn into the battery pack -but it was not being sent down the terminal wires, they stayed very cool (AWG 2/0).

I have not used extra washers to increase surface area on these studs. I first made sure that the stud bolts were very tight into the terminal sleeve (Docan-supplied stud bolts accept an Allen wrench at one end, supporting this step). Then I tightened the nuts to almost 70 inch-pounds of torque. My battery pack handled this current - easily. (But I did stack the Docan supplied "bus bar" thin pairs on top of my own superior ones - Docan's own thin bus bars cannot easily handle this current between battery cells.)
 

grobalt

Solar Enthusiast
Joined
Jan 19, 2022
Messages
32
Today i measured 80 cells (Eve LF280K) from Docan, all are labelled with impedance between 0.17 and 0.18 - but all measured between 0.52 and 0.58 (calibrated YR1035+ and validated with Fluke). I contacted Daisy from Docan ... waiting for answer.
 

Maitake

Solar Enthusiast
Joined
Mar 21, 2022
Messages
47
Today i measured 80 cells (Eve LF280K) from Docan, all are labelled with impedance between 0.17 and 0.18 - but all measured between 0.52 and 0.58 (calibrated YR1035+ and validated with Fluke). I contacted Daisy from Docan ... waiting for answer.
Getting ready to place an order, I'd like to know how this turns out.
 
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