Flow Battery Research Collective

It is incredibly exciting to see you guys reproducing the kit! We are really excited about completely independent third parties being able to just build and run this thing.

I also just got birchwood endplates for the first test of the large scale design. These are 1.8cm thick, so stiff enough to be able to seal the cell in theory. Since there is no chemical contact with the endplate, we shouldn't have any problem using this material. I will get brass current collectors next week - Xometry just shipped them to me - and will then proceed with the first test. [image: 1752155747359-whatsapp-image-2025-07-10-at-1.25.59-pm.jpeg]

@kirk said in How should we control the centrifugal pumps? TRIAC/thyristor etc? Need help from controls/electrical people: It seems to work! At least enough for testing purposes. Here is a video: https://spectra.video/w/8xipM8aXnBkDXnu4kkRpqT Here is the code for this test: https://codeberg.org/FBRC/RFB-test-cell/src/commit/d10834bc7dd67736e708c9a33832a5602ab3ca28/firmware/FlowrateRampTest.ino

I'm no expert ether. We used quick setting plaster a lot in construction for repairs on a lot of things and now they have a "wood epoxy" which is an epoxy for wood repairs. You have a thing epoxy you brush on onto wood which provides a good bonding surface for dry rotted wood and then you mix an epoxy that works more like the quick setting plaster and creates a strong enough repair that you can nail it. These plasters and epoxies could be formed or poured to create a nice mold. For the quickset we could build up an area, then carve and shape it before it fully set. The surface is very smooth and with a spray sealer of some kind should be even better for molds. A quick look into casting, it looks like the most common is using silicon for making the mold. Yes it lets you do detail, but it is also soft and flexible. Not good for making thin plates without warpage.

@quinnale this look great!! @quinnale said in Towards a working system: In addition, by printing the gasket template for a guide, and then cutting the holes and cavity with some cheap circular punches and an x-acto knife, I got some jenky gaskets. I've done similar, it's definitely possible as you've shown! @quinnale said in Towards a working system: Also, should I have made this a blog post? Happy to delete and move if that's better. Oh no worries there, I made that category in part as a container for Daniel's blog - WordPress and our forum software can interact (via ActivityPub), so that we can reference and comment on his (and other people's) longform WordPress posts directly here in the forum, like what's happening here. @quinnale said in Towards a working system: Also, here's an update on the 3D-printed pump! Been running it for about an hour, no issues. Unlisted Youtube video . If anyone is curious I can provide more details. Gonna try run it to death, see if the plastic or the tubing fails first. That's awesome! Having another pump option besides only Kamoer would be great (esp. an open-source one!). It's this pump you've used? @sepi said in Towards a working system: eing a complete newb, I slowly gather an understanding of the individual components of the cell. Glad to hear it, that's one of the whole points of this forum!

@sepi Unless you are very experienced soldering small components I would suggest not doing this. Some of the expensive components are tiny and easy to damage, either by overheating or by soldering multiple legs together and causing shorts. I tried soldering my own mystat 3 times (without success) before I got my first working one from pcbway. I am however, not good at all at soldering.

I ordered most parts now. Fingers crossed they are correct. I went for the Ti foil instead of the graphoil since it was way cheaper. Fingers crossed

Ah, in the FAQ ... Yes, was thinking wrong from other and not so good sources.

@kirk very cool!

Stephen Hawes of Opulo has compiled some of their tools here: https://midscale.io/docs The AutoBOM one seems to be based on those workflows above and looks pretty interesting

@gus @SamAuc ABS may work with an all-copper chemistry!

That's great! Do you have a link to one or know where we could procure one to test?

@kirk I hadn't spotted this years update to @tserong system - Thanks for the pointer! Bummer about redflow going under. We've gone for the riskier lump of lithium strapped to the outside of the house (Just as well Snug never has bushfi...oh). Can confirm that the #tasnetworks cablepi objects when we're off-grid. Reminds me I need to chase installer as our grid-tied inverter (on the essential load side) rightly objects to the 55.1Hz Sonnen runs at when in island mode - Want to decrease this.

@H4K1 no need to build the flow battery and test chemistry to help the project out! You can also build and test just with water, especially the larger cell we'll build. But if you can do CI/CD and firmware now then that's great! You'd be the only one on the project now with those capabilities, so a huge bonus. It will help make a framework that we'll benefit from as the project advances and hopefully save us some time as we improve and develop, so we can focus on what we're all best at and enjoy!

Here is an updated version! https://spectra.video/w/nJ8XNYu1MXNPSDLKV3KVTh

Updates from @danielfp@chemisting.com during today's meeting: I started a test with 2M KI, 1M ZnCl2, 2M NH4Cl, 5% Trieg with Daramic and felt on both sides. Going to charge to 1.6V at 10mA/cm2, see if it makes any difference regarding stability with Trieg on subsequent cycles. I did one cycle at 10mA/cm2, charged to around 240mAh (noticed a dip indicating start of solid I2 buildup, so cut it there), discharged 180mAh. I am now charging to 150mAh at 30mA/cm2, normally I would see drops in capacity with cycling with Trieg at this level, we'll see if they happen. [image: 1747325869007-57810618-3e33-4f12-ad81-bc93fc620bcd-image.png] Seems to be stable now at 30mA/cm2. I will leave it cycling here longer, see if it starts decaying. [image: 1747325889390-778d48dc-3d94-4012-9de2-a0c45a4727b0-image.png] ok, went for 9 cycles with no issues at all. I am now going to cycle it to 1.65V, to the Nernst limit, see if it continues working equally well. Charging to 1.65V showed the weird start for the discharge curve, although with no apparent deterioration of the cycle characteristics after the first cycle. No evidence for solid iodine formation was present, so the solution is very well behaved. [image: 1747325914186-cc5413ce-ad2d-4ae5-b64d-ed8939f213cf-image.png] Test at 15mA/cm2 of the same cell. Some deterioration is now evident, charging to 1.55 V [image: 1747325934195-2dbc77b1-de09-4492-a3e2-5997e2517c81-image.png]

My latest quote is 315$ with assembly included by PCBWay. That's expensive but not prohibitive. Thanks for the input!

Reading the posts about the different pump designs, it makes more sense. More background reading to do. TY

Hi Otmar! I think it would be helpful to see a rough schedule of the workshop and time allocations per topic/activity - then it would be easier to give feedback for the site, based on specifics of the activity the site is meant to complement!