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An open-source flow battery kit

dualpower.supply

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Re: An open-source flow battery kit

#91

Post by rootusrootus »

avhon1 wrote: post #64
rootusrootus wrote: post #54

Earlier quoted context omitted.

You would not use a laptop-style lithium battery for battery backup for your home. You would use LFP. It does not have the burst-into-flame problem you are thinking of. At some point I expect we will look back at the era when we used really flammable electrolytes and laugh about how wild that was. I bet we are not that far from it being just a memory.

PowerWalls use NMC cells. And the majority of "diy powerwall" builds are reclaimed 18650 cells.

There's been a rumor for a while that Powerwall 3 is LFP, but I don't think anyone has actual confirmation on that.

I've seen occasional 18650 builds for DIY powerwalls but the vast majority are using prismatic LFP cells. Way easier to wire up, cheaper (unless you have a secret source for surplus 18650s), and minimal fire risk.

Re: An open-source flow battery kit

#92

Post by BobaFloutist »

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…

As someone completely ignorant in the field, my impression is that the point of this is to create something that relative amateurs (or research professionals on a budget) can use to tinker with various chemistries to achieve those huge breakthroughs (that we keep seeing in every other kind of battery, because it turns out batteries have a lot of room for breakthroughs).

Re: An open-source flow battery kit

#93

Post by kirksmith »

kirksmith wrote: post #77

Wow, hi all, I am Kirk, the author of this blogpost, never thought my small ARM board home server would handle this much traffic! Currently reading through these posts, feel free to ask questions. Great to see interest. FYI, I am quitting my postdoc job in two months to work on this full-time, which should help the rate of progress, but my main source of income will stop. We hav ea small but it will only cover a few…

*typo: meant to say we have a grant from NLnet https://fbrc.dev/posts/NLnet-funding/ , which will cover a few months of full-time work (for one contributor)

Re: An open-source flow battery kit

#94

Post by BobaFloutist »

jhayward wrote: post #51
almostnormal wrote: post #40

Earlier quoted context omitted.

Energy storage is the problem that needs a solution, e.g., storage from summer to winter.

Seasonal energy storage is the last thing that needs to be addressed in the storage hierarchy. There are very high-value targets starting on very low time frames.

Seasonal energy storage is the last thing, but that also means it's the last caveat, as far as I can tell. If we figure out seasonal energy storage, that's it. Solar just wins. There's no further need for fossil fuels. We're done.

I guess there's still aircraft.

Re: An open-source flow battery kit

#95

Post by culopatin »

Can this be combined with uphill water storage so you store both kinetic and chemical energy? The pump would store water uphill as it does now, but when it flows down it goes through the membrane and also generates power this way? Of course it robs some of the momentum used for the turbines but idk, maybe it’s more efficient?

Re: An open-source flow battery kit

#96

Post by BobaFloutist »

Workaccount2 wrote: post #35
Dylan16807 wrote: post #22

Earlier quoted context omitted.

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 3…

I see what you are saying, in reality the right energy storage is very application dependent. The crux of my argument is that I cannot think of many applications where a commercial grade flow battery is the best choice, much less a single application where a DIY flow battery is the best choice.

>The crux of my argument is that I cannot think of many applications where a commercial grade flow battery is the best choice

I think the argument against that is that we've spent tens of thousands of person-hours a millions of dollars more researching, developing, improving, and refining lithium-ion batteries than we have flow-batteries, and the purpose of the project in OP is to make it easier to tinker with flow-batteries.

Think of how much better lithium-ion batteries have gotten since we first started using them. We went from "You simply cannot achieve the energy density to propel (tethered) cars without fossil fuels" to "Oh wait we have electric cars now." in like a decade, and in the decade since them, lithium ion batteries have improved in every metric by at least an order of magnitude. We simply don't know how good flow-batteries can get, because we haven't tried, and it's silly to say "why bother trying, they're not very good right now" when we've just seen how much of a difference it makes to invest into this sort of technology.

Re: An open-source flow battery kit

#98

Post by metadat »

kirksmith wrote: post #77

Wow, hi all, I am Kirk, the author of this blogpost, never thought my small ARM board home server would handle this much traffic! Currently reading through these posts, feel free to ask questions. Great to see interest. FYI, I am quitting my postdoc job in two months to work on this full-time, which should help the rate of progress, but my main source of income will stop. We hav ea small but it will only cover a few…

Hey Kirk, this is a neat project and I admire your high level of commitment!

Question: What happens to the liquids once they have been used up and depleted? Is there a "recharge" procedure? If they can be reused, how many times before they become disposal waste?

Re: An open-source flow battery kit

#99

Post by Fatnino »

moffkalast wrote: post #37
RobotToaster wrote: post #29

Earlier quoted context omitted.

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

That wasn't because it was a proof of concept tech, but because Stratasys was effectively patent trolling it since the 80s.

"was"

They are still busy patent trolling today.

Re: An open-source flow battery kit

#100

Post by rini17 »

culopatin wrote: post #95

Can this be combined with uphill water storage so you store both kinetic and chemical energy? The pump would store water uphill as it does now, but when it flows down it goes through the membrane and also generates power this way? Of course it robs some of the momentum used for the turbines but idk, maybe it’s more efficient?

Uphill water storage has little energy density, you need huge reservoir to get useful amounts of energy.
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