Cell questions

[duffski]

Hello all! I'm new here but have been reading as much as I can of these posts lately and am hoping to jump in on making my own battery sometime soon-ish.

My plan: I plan to build my own battery and hook it up to a growatt 6kw off grid inverter (the one with the transformer) and set some circuits up on a continual ups, essentially. Initially I will not have solar connected, I will be doing this in phases as the money is available for each portion, and will use it for grid down type situations power a separate panel with some select circuits in my house. Eventually I plan to add solar to it and have some (and hopefully someday all) circuits powered by solar and battery then assisted by grid when needed.

On to the battery question. I found these prismatic cells on alibaba. I'm not sure of the truth behind the claims but I like the design with the covers that can cover the terminals on each end. Now I could be way off on my math, but when I calculate it out, needing 16 of them to make a 48v battery, it would cost $864 for 16 cells at $54 a piece. With the listing of 200ah that would give around 10kwh of power. That brings the price to $86.40 / kwh?? If it's true, this should be a great deal, but as we all might know, claims and real world tests don't match up with a lot of these listings and cells.

Just curious if anyone has any thoughts on these cells or if anyone has these cells? From Noah's Ark: Index they appear to match the styling and build of the GBS cells but maybe different as the listing is showing the positive terminal on top and the negative terminal on the bottom of the cell?

I'm not in the immediate purchase phase yet so I'm still planning and working things out, but if these are indeed legitimate cells that match their rated listing, I see them being one of my top contenders when the boss lady gives me the green light. Just looking for some discussion and thoughts on the cells listed. Thanks for any consideration!

 

[DLTooley]

It looks like a new product. Free shipping too.

 

[Bob B]

First I've seen these cells .... I like the look of them and that is a pretty good price.

Please order some and let us know if they are any good.

 

[duffski]

I just might have to order some and order some testing equipment to test these.

I know that a lot of factors go into the quality of the battery but I looked at the listed weight of the cell (5.7kg). I then went to gbs energy’s website (since the cells look similar) and compared to their listed weight for 100ah cells (2.3 - 2.9kg) and it tracks to about the right weight of double with double the capacity.

I will have to think on it this weekend and get a supply list together for some inexpensive testing equipment to test the claimed ratings.

 

[Steve_S]

TBH, This is NOT a Known Good Vendor. We have many Known Good Vendors who will supply exactly what you order and then there are Others and plenty of them. In dealing with these companies, One Axiom always rings true, You Get What You Pay For ! Even the marketing of Matched & Grade-A cells is played with quite Loosy Goosy !

The Above Battery Cells shown are "Too Good to be True" honestly, those cells (NEW, proper factory Grade-A) sell for quite a bit more, so those are either B or C Grade or Used - Possibly Broker supplied cells so without any provenance, they could be new old stock, used or defect batches or ... who knows.

PLEASE BE CAUTIOUS !
Stick to Known Good Vendors with a Reputation - we have several used here and people write it up.
There are NO ONCE IN A LIFETIME DEALS !!! There are always good deals to be had
Due Diligence and asking lots of questions is important.

TIP to Save Bucks !
Many Cell suppliers can supply added gear as well, such as BMS, Active Balancers, fuses and so on. Shipping things together can save on courier costs (you'd be surprised !) Coordinating such can be a tad confusing and as a "shopper" it would be up to you to be quite specific as to what you want... Most of the Vendors are Representatives and not engineers or builders and have no clue, they just sell products people ask for.

A CLARIFICATION to Save your Keister & the Wallet attached thereto ! (and a Marriage Saver too {in some cases} )
Translation Software enables vendors to play LOOSE with terms - a convenient excuse at time... sad but true....
Many Vendors FLOG cells as Matched. THEY ARE NOT !
They are only Voltage & IR (Internal Resistance) matched using a small handheld cell tester like a Yaorea YR1035+. This is done at the storage voltage they are at where they match up cell voltages & IR at the static state. This is NOT properly Matched & Batched.

Matched & Batched (simple explanation), means all cells are put on a Test Rig, they are Charged to full, discharged and cycled through 3 Times at various Charge/Discharge rates with sampling every few minutes. Once cycles are completed, cells are matched according to their characteristics through those cycles so they match through their usage cycles.. This process can add between 25-50% on top of the cell cost due to the time it takes and other factors. VERY FEW VENDORS actually provide Genuine Matched & Batched cells with actual cell reports with the results for each cell tested.

What's the Difference? In Broad Shot terms.
Matched Batched cells will ALWAYS test out at higher capacity & even level IRs. Example with 280AH cells.
-- Matched & Batched typically come in at 288-295AH gross capacity.
The IR between the cells will be less than 1.0 difference across all cells across ranges.
These will NOT deviate more than 30mv (on average) during charge/discharge cycles.

-- BULK/Commodity/Unmatched cells will usually be between 270-280AH
The IR between the cells will be greater than 2.0 difference across all cells across ranges. Possibly as much as 5.0 out.
These will have RUNNER Cells which can either reach Full 3.650Vpc while the others are still at 3.400 OR they can reach empty @ 2.500Vpc before the others. Both cases will cause a BMS to Safety Trip for Hi or Lo Voltage disconnects.
They can deviate by as much as 1mv per AH of storage capacity, so for a 280AH cell based pack that can be as much as 280mv differential between cells (NOT GOOD).

ONE Known Good Vendor I can recommend which MANY Members here use with Great Success is Luyuan Technologies and Amy Wan (the Owner). She offers both Factory Matched & Batched cells with reports OR Bulk Commodity cells (factory sourced, not from Brokers). The company deals direct with Manufacturers and no brokers therefore the provenance of all the cells is known. That means a slightly higher cost BUT you do get what you pay for.
LINK HERE:
https://szluyuan.en.alibaba.com/?spm=a2756.trade-order-list.0.0.110d76e9kv6ApB
For a Guide on Assembling & Prepping your cells, please refer to this Resource:
Luyuan Tech Basic Lifepo4 Assembly Guide

Hope it helps, Good Luck
Steve