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marshman wrote: ↑Sun Jan 15, 2023 2:27 pm
32 cells gives me around 28kWh of storage. I currently have 6 x US3000C Pylontechs which I will be selling very shortly, once they have gone I will get another 32 cells to give me 56kWh - which based on recent performance of the 21kWh of Pylons - will work nicely in the dark winter months. Removing the need to do some crystal ball gazing trying to predict how much PV generation I will get the following day and deciding how much overnight charging to do. Frustrating when I get it wrong and it is sunnier than expected and excess generation then goes to the grid.

marshman wrote: ↑Sun Jan 15, 2023 2:27 pm Having observed what others have done and done some "back of fag packet man maths" type calculations I took the plunge and procured 32 LF280K cells. They arrived in early December but life (and xmas) got in the way and I have only just finished sticking them all together. Part of the hold up was having to shift the 6 Pylontechs as they were "in the way" and then building a shelf to carry the 170kg of cells. Whilst I was at it I put in two shelves to allow for "future" expansion.

32 cells gives me around 28kWh of storage. I currently have 6 x US3000C Pylontechs which I will be selling very shortly, once they have gone I will get another 32 cells to give me 56kWh - which based on recent performance of the 21kWh of Pylons - will work nicely in the dark winter months. Removing the need to do some crystal ball gazing trying to predict how much PV generation I will get the following day and deciding how much overnight charging to do. Frustrating when I get it wrong and it is sunnier than expected and excess generation then goes to the grid.

I haven't switched over to the new stack permanently yet as I am still "top balancing them" - long process with some 560AH of capacity! With a collection of power supplies and a couple of car batteries I can just about get 10A at 50 odd volts to charge them. I did use the inverter and some of the precious sunshine a couple of days ago to do some of the heavy lifting and charge them to around 95% S.O.C. but at that point at least one cell was pretty much fully charged, so I am now proceeding with caution and allowing the balance circuit to do its thing.

I went for a 16S2P format - i.e. 16 pairs of cells in series rather than two "packs" of 16 in parallel. Main reason is it only requires one balance circuit and one BMS. It did mean I had to fabricate a load more bus bars. I made those out of some "handy" copper strip - in fact a length of old lightning conductor - suitably drilled and sleeved with heat shrink. Hardest part was making the elongated holes. The pack is sitting on the shelf as 2 stacks of 16 cells. I spent ages looking at the "clamp" / "don't clamp" debates and in the end decided to clamp them between end plates. The length of 16 cells is approx 47" and standard threaded bar only comes in meter lengths - and works out quite expensive when you need 8 lengths - so I fabricated the side bars from some ali sheet I had "saved" from somewhere. The end plates were 1/4" thick ali plate. The cells were separated using some "Corex" (corregated plastic sheet), again from my "it'll come in useful one day" pile. I still need to box it all in and cover the top.

The 6 US3000C Pylontechs are less than a year old and still showing 99% S.O.H. I will be selling those shortly, hopefully as a job lot including 6 pairs of Pylontech brackets and set of long leads. I have all the original packing and documentation and also the Battery view software and lead. They are "plug n play" and have never missed a beat. If interested send me a PM.



6 x US3000C, 6 pairs of brackets, long leads, battery view s/w and lead - for sale soon!


Some pics below: will add more later.

sw25481 wrote: ↑Mon Jan 16, 2023 11:46 am When you do swap in the new stack are you concerned about your Inverter talking to your new BMS? I can't decern exactly which of each you have. Perhaps that is not important for you

marshman wrote: ↑Mon Jan 16, 2023 9:18 pm One "problem" with leaving just one Pylontech battery "communicating" with the inverter is that I think the BMS will limit the charge/discharge current, which is not what you want.