An open-source flow battery kit • Hacker News Board

Re: An open-source flow battery kit

#21

Post by entropicdrifter » Tue, Aug 13, 2024, 6:14 PM UTC

Workaccount2 wrote: post #13

marcosdumay wrote: post #9

Earlier quoted context omitted.

You are missing that this is just some salts dissolved in water, while the 18650 is a highly complex device. How much does it cost to store 10m^3 of water? And hos much does it cost to store the same energy in 18650 batteries? Also, the internal resistance depends entirely on how many cells you have. But a practical battery wouldn't use paper.

>Also, the internal resistance depends entirely on how many cells you have. Right, from the one study I can find, commercial flow batteries have about 10-20x the internal resistance of a lithium ion battery, so the match the power and energy capabilities of a single li-ion cell you would need a liter of electrolyte and about 30 (!) cells (3 for voltage x 10 for power). And that is for a commercial quality flow batter…

Their use cases would become extremely relevant to people trying to rebuild society from scratch, I'd imagine. This device is so simple you could probably build one in the woods with nothing but a basic survival kit given a year or two alone.

So that's something. Learning how to build one from scratch seems worthwhile, much like learning to build a radio from scratch

Re: An open-source flow battery kit

#22

Post by Dylan16807 » Tue, Aug 13, 2024, 6:26 PM UTC

Workaccount2 wrote: post #13

marcosdumay wrote: post #9

Earlier quoted context omitted.

You are missing that this is just some salts dissolved in water, while the 18650 is a highly complex device. How much does it cost to store 10m^3 of water? And hos much does it cost to store the same energy in 18650 batteries? Also, the internal resistance depends entirely on how many cells you have. But a practical battery wouldn't use paper.

>Also, the internal resistance depends entirely on how many cells you have. Right, from the one study I can find, commercial flow batteries have about 10-20x the internal resistance of a lithium ion battery, so the match the power and energy capabilities of a single li-ion cell you would need a liter of electrolyte and about 30 (!) cells (3 for voltage x 10 for power). And that is for a commercial quality flow batter…

Unless you're flying a drone, you don't need to match the power and energy capabilities of lithium ion.

On top of that, you don't have to match the internal resistance to match power. If you have plenty of material to absorb the heat, then you can tolerate more percentage points of loss.

In particular, while lithium ion batteries can be built to sacrifice discharge rate for a bit of extra capacity, something like a 3C discharge rate is easy enough to reach. And if your use case is powering a building for several hours, you might only need a .2C discharge rate. That would mean lithium ion as a technology is 15x overqualified, and a flow battery that gives you 10x less power would still be overqualified.

Re: An open-source flow battery kit

#23

Post by EricE » Tue, Aug 13, 2024, 6:29 PM UTC

Workaccount2 wrote: post #13

marcosdumay wrote: post #9

Earlier quoted context omitted.

You are missing that this is just some salts dissolved in water, while the 18650 is a highly complex device. How much does it cost to store 10m^3 of water? And hos much does it cost to store the same energy in 18650 batteries? Also, the internal resistance depends entirely on how many cells you have. But a practical battery wouldn't use paper.

>Also, the internal resistance depends entirely on how many cells you have. Right, from the one study I can find, commercial flow batteries have about 10-20x the internal resistance of a lithium ion battery, so the match the power and energy capabilities of a single li-ion cell you would need a liter of electrolyte and about 30 (!) cells (3 for voltage x 10 for power). And that is for a commercial quality flow batter…

A flow battery isn't going to burst into extremely high temperature flames in a self-sustaining not easily extinguishable fire that also spews toxic fumes in mass quantities.

I'll take a basement (or garage) with a flow battery over lithium ion ANY day of the week if I want battery backup for my house.

Re: An open-source flow battery kit

#24

Post by ForOldHack » Tue, Aug 13, 2024, 6:29 PM UTC

perlgeek wrote: post #8

Lots of software started this way: as a toy, a proof-of-concept, a learning opportunity for the programmers. I really hope that they find interested people who join their experiments, and build something awesome and open together.

This looks like a toy, but its INSANELY COOL! You build a proof of concept? This technology is cool.

I was at a tiny house competition, and we were using golf cart batteries, and the winner: The University of Santa Clara, CA:

"The house stores its energy using saltwater batteries, the only batteries in the world to be Cradle to Cradle certified."

https://www.tinyhousebasics.com/revolve/

Re: An open-source flow battery kit

#25

Post by ForOldHack » Tue, Aug 13, 2024, 6:38 PM UTC

Workaccount2 wrote: post #2

I cannot see how this is useful outside of being a fun student learning program. From the data it appears a battery with 1L of electrolyte provides about 18Wh of energy. Mind you this is at ~1.2V, which isn't especially useful without a boost converter. With a boost converter though you would need a low internal impedance from the battery, which I highly doubt is any good with a paper membrane (from what I understand…

There are two key details you are missing:

1) Its scalable to dishwasher size, ( enough to power a tiny house )

2) If you shot it with a bullet, it would just leak salt water. That is all. Lithium Ion will explode:

Now here is the quiz: If you have a cell phone that is inflating, do you A) Dunk it in water? or B) Toss it in a full document safe? or c) Quickly empty your document safe, and toss it in?

If a flow battery leaks, you can toss in a chicken into the delightful brine.

Since you cannot scale this easily to Utility sized batteries easily, the D.O.E. is not interested. i.e. if you are looking to scale this to a couple of hundred megawatts, just stop reading and thinking about this now. This is NOT mobile. Its not useful for cars or cities. Its right sized for homes.

Re: An open-source flow battery kit

#26

Post by mschuster91 » Tue, Aug 13, 2024, 6:38 PM UTC

Workaccount2 wrote: post #13

marcosdumay wrote: post #9

Earlier quoted context omitted.

You are missing that this is just some salts dissolved in water, while the 18650 is a highly complex device. How much does it cost to store 10m^3 of water? And hos much does it cost to store the same energy in 18650 batteries? Also, the internal resistance depends entirely on how many cells you have. But a practical battery wouldn't use paper.

>Also, the internal resistance depends entirely on how many cells you have. Right, from the one study I can find, commercial flow batteries have about 10-20x the internal resistance of a lithium ion battery, so the match the power and energy capabilities of a single li-ion cell you would need a liter of electrolyte and about 30 (!) cells (3 for voltage x 10 for power). And that is for a commercial quality flow batter…

> I'm not trying to say flow batteries are stupid or dumb, but their use cases are going to be very limited without some huge breakthroughs that will probably dramatically increase the complexity too.

The largest use case is going to be grid scale storage, and for that one a bunch of dumb tanks and a bank of cells are far easier to handle and less risky than a bunch of li-ion cells that can go into runaway for whatever reason.

Re: An open-source flow battery kit

#27

Post by 0cf8612b2e1e » Tue, Aug 13, 2024, 6:51 PM UTC

ForOldHack wrote: post #25

Workaccount2 wrote: post #2

I cannot see how this is useful outside of being a fun student learning program. From the data it appears a battery with 1L of electrolyte provides about 18Wh of energy. Mind you this is at ~1.2V, which isn't especially useful without a boost converter. With a boost converter though you would need a low internal impedance from the battery, which I highly doubt is any good with a paper membrane (from what I understand…

There are two key details you are missing: 1) Its scalable to dishwasher size, ( enough to power a tiny house ) 2) If you shot it with a bullet, it would just leak salt water. That is all. Lithium Ion will explode: Now here is the quiz: If you have a cell phone that is inflating, do you A) Dunk it in water? or B) Toss it in a full document safe? or c) Quickly empty your document safe, and toss it in? If a flow batter…

   … if you are looking to scale this to a couple of hundred megawatts, just stop reading and thinking about this now

I thought that was one huge appeal of flow batteries is that you can basically infinitely scale them. China has a 100MW installation (potentially more since this 2022 report)

https://www.pv-magazine.com/2022/09/29/china-connects-worlds...

Re: An open-source flow battery kit

#28

Post by Retric » Tue, Aug 13, 2024, 7:21 PM UTC

Workaccount2 wrote: post #13

marcosdumay wrote: post #9

Earlier quoted context omitted.

You are missing that this is just some salts dissolved in water, while the 18650 is a highly complex device. How much does it cost to store 10m^3 of water? And hos much does it cost to store the same energy in 18650 batteries? Also, the internal resistance depends entirely on how many cells you have. But a practical battery wouldn't use paper.

>Also, the internal resistance depends entirely on how many cells you have. Right, from the one study I can find, commercial flow batteries have about 10-20x the internal resistance of a lithium ion battery, so the match the power and energy capabilities of a single li-ion cell you would need a liter of electrolyte and about 30 (!) cells (3 for voltage x 10 for power). And that is for a commercial quality flow batter…

1 liter of electrolyte is nothing for a flow battery, the smallest scale they become a serious competitor is ~10m3 (10,000L) tanks which are ~(7 foot X 7 foot X 7 foot).

Start taking GWh of storage and lithium ion technology gets really expensive and has a lot of associated risks. Flow batteries on the other hand don’t need to worry about a single cell failure resulting in a fire which then spreads.

Re: An open-source flow battery kit

#29

Post by RobotToaster » Tue, Aug 13, 2024, 7:22 PM UTC

perlgeek wrote: post #8

Lots of software started this way: as a toy, a proof-of-concept, a learning opportunity for the programmers. I really hope that they find interested people who join their experiments, and build something awesome and open together.

Home 3d printers started as repraps that could barely print a shot glass.

Re: An open-source flow battery kit

#30

Post by mikewarot » Tue, Aug 13, 2024, 7:47 PM UTC

It's my understanding that iodine is one of those things watched very closely by the TLAs enforcing prohibition. Be careful, lest you end up unable to move about freely because this gets you on a list.