10kWh LifePO4 DIY Battery Addition..... Here is my write up.

Ouch, that's pretty rubbish alright.

I got 16 no. 280ah cells from pwod. Didn’t get anywhere with a comprehensive dispute on AE. Cells were very closely matched at 238ah and have been performing well. I am happy overall but wish they would advertise them accurately. I paid €1950 before Christmas.

Nyon are €2387 for 230ah cells.

I think the next time, I will consider ordering from Nyon as I did find the whole AE experience stressful. Just my opinion.

It is a fair point.

I see on the small print on Nkon that they say if you test their cells and one is out of line with the others they send you, they will replace it. If they all test similar but low, then they won’t as they argue that it may be your test procedure or equipment.

I still have some doubts over my own test of the pwod cells and without investing in more expensive equipment (which I don’t intend to do) won’t ever be entirely sure.

Anyway, it has been a great experience building the battery and seeing it earn its keep. Building your own will save a tonne loads.

I've just finished testing 16 cells from PWOD, advertised at 180-190ah with an internal resistance of 0.2-0.5. Results: 1 x 102, 1 x 114, 6 x 117, 3 x 125, 5 x 132 with an internal resistance ranging from 0.34 -0.92. All over the shop!

I tested them at 40A, PWOD have asked me to test them again at 10A, they say that's what the factory tested them at. I presume they are trying to run down the dispute clock!

I got no where with my dispute unfortunately.

It looks like their prices have gone up substantially? These cells are now €2249

It appears that PWOD are about 6% cheaper thank Nkon

Has anyone here experience of Nkon?

The higher the amperage you test them at, the lower the tested capacity will be. You will also need to have some very decent test setup, not to lose a lot of capacity into heat into your cables and equipment. Test them at 100A continuous and I doubt any of your cells even makes 100Ah!

Afaik official capacity testing is usually done at a very low C rating. Way lower than your 40A divided by the 180-190A official rating

You could chance your arm and start a dispute of course, maybe you'll get a partial refund.

I tested a couple at 20A and got the same result. I am also testing some 275ah cells at the moment and achieving 272ah. Most of these cells are rated based on a discharge current between 0.2C and 1C at 25degC as per the datasheets. The 10A test current that PWOD want me to test at is .05C which will probably give a slightly better result but nowhere near 180ah.

Yes they are EVE LF280K cells. I agree there is no comparison on the structure but once they are well protected I don't see any issue using them. Could also clamp them as specified by EVE (300kgf)

16mm2 would have considerably heat losses with 40A, even with a short cable. Just for the craic "off grid garage" style, could you run the same test on the same cell at the same speed with it connected to the tester with short copper bus bars or at least 35mm2 cable and see what the difference is? Would be very interesting to find out!

Yeah what I like about him is that he is happy to put any (preconceived) ideas to the test and he is unhappy until he has explored all possibilities and has some clear test results. Was surprised myself about the outcome of his busbar test!

They are EVE cells Docan sell so they are the aluminium ones.

Once they are put together I don't see the issue of them being softer. I'm not planning on moving them too often.

Also based on plenty of capacity tests online one Docan EVE cell is close to two CALB ones, so fits in smaller area if that is an issue.

With my poor OYE cells and the 4 replacement cells I have to get from PWOD I spent 1608eur on the 20 cells, with 16 in use. Of the other 4 one was completely useless under any load, will keep others as spares if same happens again. Seplos is giving me a capacity of 122ah, so approx a 6kwh battery.

NKON are offering cells 280ah cells at 2361eur*, without the hassle of 3 months delivery and not knowing what level of battery you are going to get. If I expand over the summer I will be purchasing from NKON (or Docan if there is some more positive feedback).

*NKON B-Grade Warranty

"B-grade cells are cells usually did not qualify as A-grade by the manufacturer. This may be due to optical imperfections, higher self-discharge, lower capacity and/or higher internal resistance. Unfortunately manufacturers don't tell which aspects or aspects are the reason to mark a a specific cell as B-grade. We have sold several and get seldom negative feedback. We tested several eve B-grade and one had about 2% lower capacity, the other ones we did not find a difference with A-grade cells. We don't advise B-grade for high performance electric vehicles but for home energy storage they will work fine. In case you get one which performs significant less than the others like lower capacity, high self-discharge or fast wear we will replace it. Take care that we don’t put a lot of trust in a simple test of a single cell, if you buy 16 cells and you test them and they are all 6% lower than expected then your test gives to low results. If you buy and test 16 and 15 cells give you 100% and one cells gives 5% lower results then we will replace one. When we buy cells the cells are tested for voltage and internal resistance. Also a couple of every batch are tested for capacity, and if one gives less than 100% capacity we test the whole batch and discard the bad ones or don't buy the batch at all. Lot of seller in china buy B-grade cells, test them, even swap qr-codes and sell the good looking and performing as A-grade cells. We believe our B-grade cells are the same as lot of A-grade cells from China, including the well known resellers there with good reputation. We give regular warranty on these cells (at least 2 year)."

Has anyone used OYE for cells on aliexpress? They seem similarly worded to pwod but are cheaper. I've got some assets maturing in a couple of months and I intend to use them for some cells to replace my dyness batteries.

EDIT: Link:

https://www.aliexpress.com/item/1005004869758958.html

They are half the price of PWOD cells at the moment. I hope it stays that way.

$1500 per each 16 cells. Not bad. I can see me getting to 16s4p quite quickly if those are the prices. (Thanks to a helpful tip from a boardsie, changing the price to USD makes everything cheaper too as Ali like to make money on the forex)