Flow Battery Research Collective

@quinnale Hey, thanks for joining Alex and welcome! Let's set up a chat - send us an email at info@fbrc.dev and we can set something up - would be very happy to hear what you're up to and how we can collaborate. We have our regular meetings weekly on Thursdays from 12:00 PM - 1:00 PM EST, but I won't be able to attend tomorrow's unfortunately.

We print on PP packing tape often and haven't had issues with leakage from that to date. There is a great solution here though which people have used with success, less fiddly than PP tape https://www.ppprint.de/produktkategorie/printing-kits/

Some PP filament reels come with a PP foil adhesive surface, is that what you used?

Most often, problems with PP are related to:

1. getting it to print at all/not warping
2. PP parts that are dimensionally accurate but leak internally/externally due to print settings/any number of reasons - but 100% infill and 5 perimeters seems to work most of the time (it can be filament/printer dependent)

The reservoirs you can leak test now somewhat by filling with water and covering the barbed fittings.

The flow frames can be tested with water once you have the cell hardware + gaskets.

Can't wait for the rest of your parts to come in and see how you get on!

And did you order a MYSTAT from PCBway or similar/do you have another battery cycler/potentiostat available? IIRC you are at a university lab, right?

So excited that you're doing this - and those prints look excellent! 100% in PETG is fine for the endplates, probably overkill even. I will make this clearer in the docs.

Are the bottom of the endplates reasonably flat?

You say you've ordered the rest of the components - the pumps/tubing are probably the most important selection and hardest to obtain. Did you have any other issues?

@gus said in New member introduction thread!:

@kirk Thank you! I'm starting to 3D print all the components.

Good luck, please let us know how it goes!

@lahuertadepili said in New member introduction thread!:

Hola , somos agricultores en españa, Mallorca, nos apasionan las tecnologías que ayuden a ser mas rentables las explotaciones agrícolas...

¡Hola y bienvenido! I think we share a similar vision

There is another farm that expressed interest in the project in the Dominican Republic: https://vivavistadelmar.wordpress.com/2024/09/24/let-the-power-flow/

One of our main contributors, Daniel, is also based in Spain and can speak Spanish fluently (unlike myself).

It will be a while before we have designed a system robust enough for practical use in a demanding environment like a working farm, but we absolutely plan to get there eventually! See our roadmap for more details: https://fbrc.dev/posts/roadmap-faq-forum/#roadmap

@gus here is a new jig design. With the latest pumps, we don't need an external motor driver anymore, so the jig could become simpler. Now, the plan is to print an external Arduino case which mounts directly to the jig, reducing print time and the size of the entire jig.

Here are the latest instructions: https://fbrc.codeberg.page/rfb-dev-kit/fabrication.html

This should definitely fit the new pumps.

@gus give me a few hours and I will confirm this for you, I will make some changes to the jig.stl file that will make it better. The holes should already be the right size but I will double check.

@gus the docs are now more up-to-date in terms of components: https://fbrc.codeberg.page/rfb-dev-kit/index_BOM.html (specific changes here: https://codeberg.org/FBRC/RFB-dev-kit/commit/0c7eae7fe7f829a2d11ad663948377c5c3419191#diff-6bf6300053fa6ad4798859a249550165c9a2ab8b)

Welcome @gus and thanks for joining! Please share any feedback no matter how small it might seem. Fresh eyes are really helpful.

The docs are close to being done but not quite there yet! I am going to check over them now, some small things have changed (e.g. gasket thickness is now 0.1 mm).

It is mostly 3D printable and there is one brass/copper plate that needs to be machined in a simple way, definitely no problem for any university machine shop. We also now have identified pumps/tubing that work much better.

@a.rahimzadegan, right now the fastest way to get the latest version of the kit is to build it following the instructions at https://fbrc.codeberg.page/rfb-dev-kit/. We would like to sell them eventually but we're not there yet.

Hi Ash, and welcome!

Apologies for the delay, I just finished moving apartments and was unavailable for several days.

Can you tell me or show me pictures of what equipment you have exactly? Do you have a version of the FBRC cell? The MYSTAT software can only control the MYSTAT potentiostat and an Arduino UNO R3 (used for controlling pump speeds). It can't be used with another brand of potentiostat at this time.

Hi Otmar, welcome to FBRC and the project, looking forward to working with you!

@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

@methylzero@mast.hpc.social said in How should we control the centrifugal pumps? TRIAC/thyristor etc? Need help from controls/electrical people:

Nice! Better than I expected honestly. At the low end of the speed range it sounds a bit unhappy. The thermal protection is only TP111 so it may not be fast enough to save the motor if it is stalled.
If this motor does work out, the manufacturer can make bigger ones and apparently you can choose the wet-side material. http://www.china-haiyi.com/product-48054-173640.html

Thank! I read some stuff that TRIACs can work for very small motors, and indeed this is only around 6 W, so I figured why not just try it. Yes, at the low end it made some funny sounds, nothing horrible, but this is not definitely not the optimal control strategy. It should hopefully allow us to do single-cell flow testing at close-to-appropriate flowrates, without having crazy fast flow or having to add a bunch of (chemically resistant) plumbing like a bypass/pump-around. For wet-side I think they have two standard options of PP and PVDF for the housing/impeller. Also, for some bigger pumps, they offer BLDC motors stock, apparently, which should be easier to slow down efficiently. Didn't know that TP111 designation either - sounds like it should auto-shut off if it gets too hot at steady state, but won't protect from a stall.

Also, just FYI, R.Flo, a Ukrainian all-iron RFB startup, posted a pic on LinkedIn with these pumps:

Which look to be the same version, but larger.

@methylzero@mast.hpc.social said in How should we control the centrifugal pumps? TRIAC/thyristor etc? Need help from controls/electrical people:

But one thing not good about these pumps is that they might not work great with really dense solutions, max. density is 1.1-1.3 depending on the model, which is .... not much.

Yeah I saw this and... we will cross that bridge if/when we get to it at this low of a price point I read the datasheets with a shaker of salt.

From CRC handbook for potassium iodide (just as a reference point for a salt we currently test with):

In real electrolytes we'll have other salts present at the same time, but even with a 1.3 SG max we may get to reasonable concentrations---as in, high enough to allow us to build out the rest of the system for a prototype. I figure over 1.3 SG the pump either fails faster or has otherwise reduced performance, but maybe we'll find out the hard way

@methylzero@mast.hpc.social @BillySmith @H4K1 @slash909uk@mastodon.me.uk

It seems to work! At least enough for testing purposes. Here is a video: https://spectra.video/w/8xipM8aXnBkDXnu4kkRpqT

Tested the pumps today, they work just fine switched on 110 V AC, will try the triac, if that doesn't work/it fries the motor, will disassemble and try to get a different motor on there.

Video of pumps running: https://spectra.video/w/9VddoPTvMvDCJ121B4fabf

Nice work, Daniel. I am thinking of plumbing solutions to the imbalance issue:

From A review of all-vanadium redox flow battery durability:

After studying the capacity fade for mixed acid electrolyte, UET [154] found that, during long‐term operation, the ratio of catholyte and anolyte concentration remained constant: 1.3:1. Based on this finding, they designed an overflow system with different volume (volume ratio: 1.3:1) anolyte and catholyte tanks, in which the volume ratio and total vanadium were kept constant. With the new design, the VRFB achieved long term capacity and efficiency stability. However, this design is only valid for the mixed acid electrolyte system. Recently, Wang et al [152] developed an electrolyte reflow method to solve the electrolyte imbalance issue for the sulfuric acidvanadium electrolyte system. Figure 10 shows the schematic of their method; without reflow, eventually all of the anolyte will move to the catholyte tank, while with reflow, the anolyte tank will always contain some electrolyte. Similar to the UET method, the volume ratio of catholyte to anolyte is a key parameter affecting the capacity stability and is highly dependent on the operating current density. Cycle life and total capacity were all improved with the reflow method.

There is also Capacity balancing for vanadium redox flow batteries through electrolyte overflow but it was retracted - they think they accidentally had a pinhole in their membrane for the test. But they did build a real overflow system:

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

I agree about loading up on sensors and then cutting them to the bare minimum as things mature---though some process sensors for chemicals can be pricey!

Are those food-safe pumps centrifugal? We need those to be power efficient---peristaltic won't do at scale.

Edit: saw your other comment, if these mag-drive centrifugal pumps are common in that industry that's great! Do you know what materials are commonly used and come into liquid contact? And what range of flowrates they can provide?