Flow Battery Research Collective

We will be presenting at FOSDEM 2026 and hope to see you there! Kirk and Daniel will be presenting at 12:30 on Saturday, January 31 in the Energy track in room AW1.126. Full details here, including the link to the livestream (talk should also be recorded and watchable later). The title of the talk is "Scaling up open-source batteries: what's worth pursuing?". Here is the abstract: Storing energy reversibly is useful. For clean energy, electrochemical batteries are one of the most attractive options. Most battery technology is proprietary, hard to recycle, and complicated to manufacture. What if that wasn't the case? We will present our collective and individual efforts with the Flow Battery Research Collective (https://fbrc.dev/) to build open-source batteries for stationary storage applications. This includes our flow battery work, such as efforts to build a larger-format cell with simple manufacturing techniques like laser cutting and FDM printing, as well as our different experiments with flow battery electrolytes based on zinc, iodine, iron, and manganese. We will also cover our individual efforts to build conventional, non-flow flooded batteries based on water and the above elements (including this work by the speaker Daniel: https://chemisting.com/2025/05/23/a-low-cost-open-source-cu-mn-rechargeable-static-battery/). We will discuss the economic hurdles facing practical implementations of these systems.

hey @DDM ! It's moving along slowly but surely. I had to move my lab around a couple times in the last months which has slowed things down a lot, just starting to get back to things! Doing some initial leak tests with water, seems like we may need beefier centrifugal pumps than initially thought to get sufficient flow (and/or I did a poor job on designing the flow frame!). I'll be ordering the next couple sizes up of the same type of pump to see how much of a difference that makes. Once we have good flow conditions the plan is to test the same Zn-I chemistry as the benchtop scale, but with about a liter of total electrolyte. Also need to get a battery cycler working for the larger currents needed at this scale, have two solutions for this right now, most likely is a MightyWatt electronic load I already have set up as a cycler (like here: http://kaktuscircuits.blogspot.com/2015/09/mightywatt-as-li-ion-charger.html).

Charging to 6Ah/L at 30mA/cm2 and discharging at 5mA/cm2. At most we only get 2-3 Ah/L of available capacity, same as if we charged to 4Ah/L. [image: 1758211363268-f3e1b8fc-98a1-4c8b-b305-b4d4a5bedee6-image.png]

In the hope that it will be useful to the future work of folks here, I've written up as much as possible about my experience patching up a failing ZCell and nursing it along. I've also included some further general notes about Redflow's hardware and software: https://ourobengr.com/2025/12/what-happened-next/