Our NEW GO-TO LiFePO4 vendor...09.20.21

cinergi

1.21 Jigawatts
Joined
Aug 9, 2020
Messages
1,166
I recall you showing photos of a big bank on racks, and making this change.

Do you get a difference in DC voltage drop, or AC voltage (seen by oscilloscope) along length of busbar?
How about difference in contact resistance between cell terminal and cable terminal? Or cable terminal to cable strands?

How do DC resistance measurements compare (if you have a way to do that.)

I've done the math on skin depth, using idealized models in engineering school.
At very high frequencies, surface roughness becomes part of the path length.

I take measurements of resistance and reactance vs. frequency for various components like chokes and transformers, using a meter that goes from 20 Hz to 100 kHz. The values change a lot over low frequency, and differ vs. DC ohms.

I also have designed, measured, used RF components, including 11 MHz transformers I hand wound with 30 awg wire-wrap wire, and procured from a vendor for production.

So my work doesn't exactly match busbar applications. I don't have equipment for high current tests other than battery/inverter and AC grid/resistive loads. But I have difficulty understanding how laminations vs. strands make a difference for battery DC 60 Hz ripple currents. I would hope kHz ripple from switcher is handled by capacitors in inverter.

I think it ends up being 120Hz on the DC side. I did have a scope on my battery for a bit and definitely saw a ripple with bus bars (let alone cables). I didn't get any details because I ended up blowing a fuse and I've become gun-shy to try again. The scope was acquired after I made the change to bus bars and I no longer have a way to do a comparison.
 

BuffaloTrace

Solar Enthusiast
Joined
Dec 3, 2020
Messages
126
First query to Powerwholesale.net representative, Amy Zheng, was way back on September 1st. All correspondence has been handled in a timely and professional manner.
Battery build to follow in near future on dedicated post.
 

Alphabavo

Solar Enthusiast
Joined
Feb 14, 2021
Messages
52
Received my cells from Jenny yesterday, much faster than we had discussed. The cells arrived in excellent physical condition with no notice swelling. All cells tested @ 3.25v +or- a hundredth.

I haven’t had a chance to capacity test, but I doubt there will be any issues.
 

Jenny Wu

Docan Technology(Shenzhen) Co.,Ltd (Direct Sales)
Joined
Aug 27, 2021
Messages
71
Location
China & USA
Received my cells from Jenny yesterday, much faster than we had discussed. The cells arrived in excellent physical condition with no notice swelling. All cells tested @ 3.25v +or- a hundredth.

I haven’t had a chance to capacity test, but I doubt there will be any issues.
Wait for your capacity test result.
 

Bvillebob

Solar Addict
Joined
Oct 21, 2021
Messages
148
Long time listener, first time caller here. I have 10KW of panels and 8 L16HC batteries for the last few years. I've been wanting to upgrade my system to lithium but the craziness with the Alibaba vendors kept me out of the market. When i heard about a vendor with USA stock I got interested and contacted Amy Zheng about buying cells. I wanted 32 cells but that was a bit above my comfort level for an unknown vendor so I ened up ordering 16 Eve 304 ah cells. She said they were in stock and would ship in two days. I sent the money and two days later got tracking info. When they arrived they were packed beautifully, in perfect condition and looked immaculate.

I contacted Amy again and tried to order another 16. Instead of the usual "OK, no problem", I got "there are shipping delays and we won't have stock in Texas until October 15-20". I said sure, no problem, but I'll be out of town during that period so don't ship until October 20 so I'll be home a week later when they're delivered. Amy said she'd contact me to confirm shipping when they were in stock. On my trip I checked my emails and found one from Amy telling me they were in stock and asked if it was OK to ship. I said yes and a couple of days later got tracking info. They arrived today and again are perfectly packed, no damage, and look perfect.

The reason I wrote this blow by blow description was to convey the quality of the communication and the ease of the experience. Sure, I paid a bit more than on of those low price vendors, but I got fast, accurate communications over and over, no BS, no delays and everything promised was delivered. This is such an unusual experience these days in any business, but partiularly in trying to buy lithium cells. I wanted to share it with the forum in case anyone was looking for quality cells and hestitating to buy from these good folks. They seem to be really trying to do things right and I hope they do well. If they keep it up they'll have a big chunk of the market in a short time except for the buyers looking for rock bottom prices and willng to deal with the consequences.
 

Dtfeld

Solar Enthusiast
Joined
May 26, 2021
Messages
10
I purchase 8 304Ah based on the feedback here. I had to wait a couple weeks, as they sold out FAST!. However, Jenny was in constant communication, the cells arrived well packaged and all voltages were right at 3.295 across the board. Digging in with some additional testing, but I'm very satisfied with the pricing , delivery, and especially the great communication Jenny provided.
 

Jenny Wu

Docan Technology(Shenzhen) Co.,Ltd (Direct Sales)
Joined
Aug 27, 2021
Messages
71
Location
China & USA
I purchase 8 304Ah based on the feedback here. I had to wait a couple weeks, as they sold out FAST!. However, Jenny was in constant communication, the cells arrived well packaged and all voltages were right at 3.295 across the board. Digging in with some additional testing, but I'm very satisfied with the pricing , delivery, and especially the great communication Jenny provided.
Also thanks for your supports and good review !~
 

Espaul

New Member
Joined
Aug 14, 2021
Messages
13
I inquired about different cells through Alibaba from both Libby Zhong and Daisy Efest who were both exceptionally helpful and knowledgeable. Unfortunately I was only ordering enough for a single 48V system and couldnt place an order from each of them.

I ended up placing an order of 304AH Eve cells from Daisy Efest and due to financial constraints I had to split the payment up 3 different ways. Daisy split them into separate orders, and despite delays was able to get them to me quicker than anticipated. The cells are perfect, packaging was absolutely the best I've ever seen.

Haven't had the chance to put them together or test capacity yet but I have no worries at all.
10/10 I'm so glad I heard about this supplier!
 

Jenny Wu

Docan Technology(Shenzhen) Co.,Ltd (Direct Sales)
Joined
Aug 27, 2021
Messages
71
Location
China & USA
I inquired about different cells through Alibaba from both Libby Zhong and Daisy Efest who were both exceptionally helpful and knowledgeable. Unfortunately I was only ordering enough for a single 48V system and couldnt place an order from each of them.

I ended up placing an order of 304AH Eve cells from Daisy Efest and due to financial constraints I had to split the payment up 3 different ways. Daisy split them into separate orders, and despite delays was able to get them to me quicker than anticipated. The cells are perfect, packaging was absolutely the best I've ever seen.

Haven't had the chance to put them together or test capacity yet but I have no worries at all.
10/10 I'm so glad I heard about this supplier!
Thank you !~
 

Shog9

New Member
Joined
Mar 27, 2021
Messages
1
Well, after my battery order from Amy Wan got blown up or whatever in that Speed King / UPS fiasco, I decided to take a chance on Docan & ordered 36 Eve 280a cells. Put together a couple of 48v packs and spent the last week hammering on them with 30-100a charge rates and 120-180a discharge rates.

They're champs! No more than 50ma deviation in voltage (with no balancing thus far) and barely even get warm. No swelling prior to assembly (they're clamped with neoprene separators). Honestly, holding up to abuse better than I expected!

Docan (Kaylee Yang was my contact) has been a joy to work with: fast answers to questions, and fast shipping. The Eve cells were in stock in Texas, but the extra busbars I ordered had to come from china - still got 'em in a couple weeks.

Big thanks for the recommendation!
 

Jenny Wu

Docan Technology(Shenzhen) Co.,Ltd (Direct Sales)
Joined
Aug 27, 2021
Messages
71
Location
China & USA
Well, after my battery order from Amy Wan got blown up or whatever in that Speed King / UPS fiasco, I decided to take a chance on Docan & ordered 36 Eve 280a cells. Put together a couple of 48v packs and spent the last week hammering on them with 30-100a charge rates and 120-180a discharge rates.

They're champs! No more than 50ma deviation in voltage (with no balancing thus far) and barely even get warm. No swelling prior to assembly (they're clamped with neoprene separators). Honestly, holding up to abuse better than I expected!

Docan (Kaylee Yang was my contact) has been a joy to work with: fast answers to questions, and fast shipping. The Eve cells were in stock in Texas, but the extra busbars I ordered had to come from china - still got 'em in a couple weeks.

Big thanks for the recommendation!
Thank you !~
 

Chuntzu

New Member
Joined
Nov 3, 2021
Messages
6
Other than ah what would be the difference between CATL 302ah and EVE LF280K 280ah cells? I saw mention in some threads that the lf280k may have more cycles in them vs other cells like 6000 vs 3000-4500. Thank you for the help.
 

JCieh

New Member
Joined
Jun 25, 2021
Messages
1
Seems their warehouse in TX is totally sold out. All 280Ah and 304 Ah and comparable are available in earliest 4 weeks. Does anybody have an idea where to get some 16 pcs. in lesse than a week to NC?
 

Jenny Wu

Docan Technology(Shenzhen) Co.,Ltd (Direct Sales)
Joined
Aug 27, 2021
Messages
71
Location
China & USA
Seems their warehouse in TX is totally sold out. All 280Ah and 304 Ah and comparable are available in earliest 4 weeks. Does anybody have an idea where to get some 16 pcs. in lesse than a week to NC?
Hi JCIeh,

Thanks for your interests and trust. The ETA for our next batch 280Ah is 24NOV. Preorders are accepted. Welcome to inquiry directly. Thanks again.
 

mealticket

New Member
Joined
Mar 27, 2021
Messages
7
The website shows US stock of some batteries. Is that incorrect? Do I just message you Jenny to place order or do I place it on website?
 

triplethreat

Solar Enthusiast
Joined
Oct 12, 2021
Messages
41
The website shows US stock of some batteries. Is that incorrect? Do I just message you Jenny to place order or do I place it on website?
I pre-ordered a few weeks ago for some of the 304AH batteries and Jenny placed a hold on shipping for me until Dec. 3rd as I will be out of town and don't want them sitting on the porch until I get home. Jenny is very easy to work with, even if you have a special circumstance like I did. Hopefully they will arrive sometime during the week of Dec. 5th and I'll be ready to do my first build. 😁 Thanks again Jenny.
 
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