Thx Kirk for sharing, I almost missed this important release. Awesome documentation as always with great methodology and insights!

Oh, pardon me. I probably used the wrong term. I noticed that the catholyte tank electrolyte level had risen higher than the anolyte and there was electrolyte migration. I guess I "re-leveled" the electrolyte. There is a 1/4 inch (6.35 mm) shunt tube between both tanks but at the time, the shunt was not able to keep up with the migration. Since I do not have a pump or a siphon or extra valves and tubing that are acid resistant, I blocked the gas pressure equalization tube between both tanks, reduced the pressure in the anolyte tank, and overpressured the catholyte tank until the atmospheric pressure on the catholyte allowed more flow through the shunt. Then I restored the pressures to as expected. In recent times, the shunt has been able to keep up with any electrolyte migration pressures.

from this paper, seems like nanomaterial synthesis needed: https://www.nature.com/articles/s41560-026-02091-w#Sec25 also they use triflate salts --- that's likely more expensive than the Zn (and, fluorine-containing, with all that entails)

@bipolaron @kirk This project in Switzerland is currently building a 2.1 GWh capacity / 1.2 GW output redox-flow battery. Scheduled to go online in 2029, and by their own PR material "the largest in the world". https://www.swissinfo.ch/eng/climate-solutions/switzerland-builds-worlds-most-powerful-redox-flow-battery/91181119

I caught the version on YT, but having the same vid on PT is great.

The battery looks interesting but has some problems. From what I've read, it tends to use up the water in the electrolyte fairly quick by splitting into hydrogen and oxygen. Also, It's working voltage is ~1.2v but it needs 1.6v (1.65v if added lithium) to take a change? The inverter I'm leaning towards now, GTIL2000, for low cost and simple connection has an input range of 45v-90v. When using a 48v LFoP battery, it only can produce about 1300w. With a 72v, it's around 1700w according post on a solar forum. One of these batteries with enough sells to put the charge voltage just below 90v with give me a battery that only has about 60v when no solar to charge it. That would really cripple the inverter. Here is a few videos of someone messing with this battery making his own electrodes and a gell electrolyte in an effort to improve the battery. https://www.youtube.com/watch?v=NaOzDt83XWY https://www.youtube.com/watch?v=0mYaei0O1sU https://www.youtube.com/watch?v=pjoxC4kwA9I

https://www.youtube.com/watch?v=t09aBKUejSs&list=PLYDTEjzfnaSVHeUiCOX5Z9G7i_AiSifpR&index=10

Also, this reminds me of the OpenAFPM project - they also use FreeCAD and provide a dashboard for people to input custom parameters for a small wind turbine generator, there is some FEM, and then design files are output. There is a video demo here: https://www.openafpm.net/cad-visualization I know a few of the folks behind that project, I'm sure they'd be happy to give input on how to accomplish a similar goal but for flow batteries.

This video seems to be AI generated and doesn't have that much real information? I have seen Ca-ion systems from (I think) a German group that looked good, but had a lot of organic synthetic steps if I remember correctly.

The cost per kWh of this is too high, the use of organic materials and ion exchange membranes puts this closer to what people do in academia and further from the cells that can be reasonably fabricated using DIY approaches. The use of an ion exchange membrane likely reduces the lifetime of this cell a lot. For a static cell, I think the sulfuric acid Cu/Mn battery we have discussed before is far more promising. That chemistry requires no exchange membranes, uses only commodity inorganic materials and cycles to 30-40Wh/L. For pure Fe batteries I am much more inclined to the Fe flow batteries.

@rowow said in Using cnc router cut PVC foam boards as cell frame: The long term goal and my personal next goal is to get into injection molding which of course is the best option. At scale, definitely! @rowow said in Using cnc router cut PVC foam boards as cell frame: Ill see about uploading the cell fusion 360 model A .step file would also be great so I could look at it in FreeCAD! I don't have a Fusion 360 license. I'd be curious to see if we could take a similar approach.

@doho said in Upcoming improvements to the dev kit: I have try-ed to download Your new files from github (.stl and .pdf), but the files all appeared as broken, even in github. The files to sprint for the new endplates are here: https://codeberg.org/FBRC/RFB-dev-kit/src/branch/clampable-cell/CAD/exports [image: 1771858819246-1c46bc80-7e99-4780-8178-46d24a289a32-image.png] I haven't updated the new You have to download them individually, unless you clone the repository with Git LFS set up---the large CAD files are handled with LFS and without LFS installed downloading the repository just downlaods a pointer/reference to the CAD file, not the actual file (at least that's how I understand it). Let me know if this works for you!

Very nice work @doho ! It's great to see your setup. @doho said in My Suction Luer Lock: But for getting reproducible resultants the flow through the cell should be down to up, but not horizontal (how much would be air isolating in the chamber when changing parts?) This is a good point, from what I've seen in other applications cells should generally clear air/produced gases by flowing against gravity from bottom to top, that is still possible with the new setup but the tubing from the pump outlet to cell inlet would have to be slightly longer. In my jig redesign I'll take this into account when writing the documentation.