I just saw this post and I agree with moth things he said. the one thing to point out is that he said he has "revived cells " from .5v this should be true and is only these cells can be 100% discharged without damage. This is a huge benefit if you have a remote system that could go down.Hello,
I want to share my YinLong LTO cells experiences here since I might be useful to anyone:
1) First it is important to know that Yinlong is owned by BYD which is an electrial vehicle producer. BYD is the one of biggest electric vehicle company world-wide beside Tesla. This year Tesla could sell more vehicles, but until 2019 BYD was world-wide #1 producer.
2) All Yinlong cells are used. No "brand new" cells exists! All new Yinlong cells are used for multiple years (up to 10 years) within electric vehicles like buses. Since the high c-rate of 10C you can load for example buses quickly at (end-)stations. Also, break/acceleration power of the buses is put on the LTO cells. From my opinion and what I have researched, you will never get/buy a complete new LTO cell from Yinlong. But for solar storage you do not need 10C at all. Please notice, I never was able to do a 10C test, but I do see my LTO cells have a higher impedance, but this is not a problem for me at all. Image of one aliexpress seller:
View attachment 30435
3) Once the impedance of the LTO cells within the electric vehicles are getting to high, the cells are removed from the electric vehicles and get rewrapped with the blue heatshrink design we know from Yinlong LTO cell. Under the heatshrink - and while used in electric vehicles - the cells looks as follows (images not from myself, found on the net):
View attachment 30427View attachment 30426
4) The capacity and impedance of the used cells is checked and this results how the are labelled/wrapped. Therefore, we do have 30/35/40/45 ah in 66160 format. By the way, within the past Yinlong also produced 55ah LTO cells in 66260 format, but they are not build anymore. We do have different cell grades: A/A-/B/C. Once a seller have posted an image about the cell grade for 40ah cells:
View attachment 30428
I can confirm on my orders (40ah only) on aliexpress, the cells are categorized with this parameters.
5) If built a 6s5p bank and have ordered 36 LTO cells at aliexpress. I have done three different orders to different times. From my experience I have gotten the most weak cells on special actions like "Single days" or "Black Friday" sales. Usually, you buy packs of 6 cells (6,12,18,24,30,36, etc) and from my experiences so far (get a lot more cells the next days...): From 6 cells, 5 cells are as promised (for example over 40ah) and at least 1 cells is way too low. I have checked/tested every single cell and listed them as follows:
View attachment 30431
View attachment 30430
The first order (#1-#12) was not on a sale and they are pretty average. The second order (#13-#24) was a "Black Friday" sale on the cells are bad quality (4 cells below 40ah). Then I complained about the cells and the seller send me the third order (#25-#36) for the halve price. While other orders are mixed in cell grades, the third order was all "Grade A" cells.
Capacity test parameters: Load to 2,6V, Cuttof at 0,5A - Unload to 1,9V, 8 Ampere discharge / This means there is some little unleft capacity which should not matter.
6) The weight of each cell is important, BUT also light weight cells can offer the capacity. I do think, they sellers at aliexpress do not know much about the cell quality they are selling. I do think the packs are packed by weight. My packs of 6 cells are all 7,175kg and 7,295kg - no matter which grade. Additionally, I do not think the sellers have the time to test the capacity of each cell there are selling. But I must add, that one ordered box someone noted by hand ">38"...
7) The cells can be balanced all ways. I have bottom-balance them, top-balance them and they are quite stable. However, due the different impedance of each cell, over (long time) they will drift. From my experience the cell drift is small, even due the different impedances. Currently, I am using an QBBM active balancer and I am quite happy with it, just works.
8) Discharge efficiency is good! Nothing to worry about. Also self-discharge is nothing to worry about.
9) The cells are very robust. I have revived cells with 0,5V or lower with full capacity. They are working on my bank as this never happens. They are happy within a very wide temperature range.
10) My usage range of these cells is between 2,0V - 2,5V. It is possible to use a higher range, but this works very stable and accurate for me and I got more than 85% of the capacity.
11) One of the most annoying things are the aluminium screw threads. Be aware if you use any sort of loctite, it might be possible you will never ever getting be able to untighten the screw anymore. Even without loctite etc., some you will destroy the screw thread on thighting. I have lost one cell since I was not be able to remove the screw anymore.
12) You can build quite cool - no amazing battery packs with Yinlong LTO cells - but from my opinion you need to check every single cells capacity and loading behavior. I can remember a cell which was really hard used and have bumpy charge/discharge curves, instead of the usual smooth ones.
13) Never buy cells from GTK manufacturer. While I never ordered ones, there capacity seems all to be lower as promised. Also, they are way cheaper then Yinlong cells. I would advice to avoid them!
14) I do not have evidences that the cells are all used. Surely, no one will tell you this, every seller only sell "brand new" Grade A++ cells. But it seems so obvious that these cells are used and rewrapped!
15) I do like them, I am really happy with them. Works perfectly for me on 12V, as on 24V. While this only based on my own opinion I hope this information is helpful for anyone!
Bye
Tobi
The threads are very fragile. One batch sent me nuts and I used those nuts but ruined 4 cells because the milling was not good on the nuts and they bound up. once this happenes the terminal gets ruined. I never had a binding problem with nuts purchased here at the hardware store. I did have a binding problem once when i drilled and tapped my own connector.
I buy nothing from ali express only alibaba directly and have found that a good dealer will provide similar full capacity cells.
I do no active balancing but allow the chargery to stop charging once any cell reaches 2.65v. I have used this method for about 3 months and the difference runs about 35mv between 12 cells in series.