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Comment by _alex_ | Hacker News Reader

I dont know anything about flow batteries, but some quick searching leads me to believe that there are two tanks of electrolytes with pumps that pump them along a membrane and then you get power across the membrane. In this small battery kit, is the idea that the battery provides enough power to both operate all its own pumps/electronics, and then output usable power? Does anyone know how much power you'd be able to get out of a small setup like this?

Looks like a cool project!

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Flow batteries have some fantastic properties. Their energy output and capacity can be scaled independently. They are safer and can be made from material that are easier to source.

They are also have high upfront costs and poor energy density, so there have not been much application outside of grid-scale deployments. Getting something practical for onsite commercial, residential, and vehicular applications have been something aggressively pursued. (Solid-state batteries being another battery tech that is also pursued).

So for someone to make a open-source DIY flow battery that can scale well can change a lot of things.

https://www.wevolver.com/article/what-is-a-flow-battery-a-co...

Thanks! This kit is for R&D and educational purposes only, because of the use of positive displacement pumps (peristaltic, diaphragm, etc) instead of centrifugal pumps, it will never be able to effectively work as a battery since the pumping energy cost is high.

Once we have materials and electrolytes validated with the kit, we plan to move to a much larger cell size which will be part of a flow battery stack, which would actually function as a battery for useful storage.

The cool thing with flow batteries is that you can scale the amount of power they store (kwh) by simply using bigger tanks. The power output (kw) you get out of them is determined by the size and efficiency of the anode and cathode.

So, in this case both are a bit underwhelming obviously. But the main point is that you can increase the kwh by simply using bigger tanks and the kw by using multiple cells in parallel or by improving the anode/cathode somehow.

What are possible dangers ? I am thinking that any potential sudden release of energy would make placement in urban areas unsafe.

Definitely looks like a great idea, fuel cells with something that doesn't outright explode if you look at it wrong. The shortcoming would be the energy density I would expect. But even so if there's something that can maybe be half as good as lithium but can be refuelled in seconds by just filling up a tank there's definitely a market for it.

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