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Is this the Holy Grail of home energy storage for DIYers?
#21
(01-30-2020, 07:29 AM)100kwh-hunter Wrote: Any thoughts?

My non-expert thoughts:
  • If you have equipment to test cells, I would create a small glass cell based on your cell design, and run it through potential operating conditions before assembling your battery.
  • If you decide to not add vents (as a precaution), I'd consider ways of modifying the cell to achieve a controlled explosion (path of least resistance).
  • I would build according to Princeton's research (some of which I've detailed previously), but fallback to Robert's model where needed (e.g., more DIY friendly carbon felt).

(01-30-2020, 07:29 AM)100kwh-hunter Wrote: A cell with dimensions of 10x10x2.5cm or 4x4x1 inch, will give you ~1.85v and ~2000mah storage max.

I haven't seen the member videos. How have you come up with these figures? Robert stated that his razor cell was 10x8x0.8cm, and has a capacity of 2432mAh, and looking at Princeton's numbers, it's even better (if my calculations are correct).

(01-30-2020, 07:29 AM)100kwh-hunter Wrote: Length and width of your cell can depend and vari on the width of your purchased material.

Smart move.

(01-30-2020, 07:29 AM)100kwh-hunter Wrote: If you would stack them on top of each other(connected with graphite sheets in between) you can stack them up to max 7 pieces ~12v.

How have you concluded that cells can only go 7 in series? Personally, I'd like to see you get to an operating range of 40-57V.

(01-30-2020, 07:29 AM)100kwh-hunter Wrote: What I think what is the real problem is that charge/discharge vs storage ratio. 1 to 10

Where did you hear that? I'm trying to figure out a good standard charge, and discharge. In the optimization papers, a test cell was charged and discharged @ C/4 for over 6 months (600 cycles) "with coulombic and energy efficiencies of ~95% and ~70%, respectively," and no decrease in capacity.

(01-30-2020, 07:29 AM)100kwh-hunter Wrote: Lets see if i can get all the materials needed and give it a go.

If you do, I'd be your biggest fanboy should you share your project (and data) online. Smile
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#22
(01-30-2020, 01:43 PM)vspin Wrote:
(01-30-2020, 07:29 AM)100kwh-hunter Wrote: Any thoughts?
  • If you decide to not add vents (as a precaution), I'd consider ways of modifying the cell to achieve a controlled explosion (path of least resistance).



This particular design doesn't really have this problem. It will produce hydrogen if charged to high amps, but generally speaking this wouldn't be a problem. But, a vent for this reason, would be a good idea. Explosion of the "battery/cell" won't happen. It's the ignition of the H2 after it's come out of the cell into the atmosphere.
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#23
Vspin,
I have the testing equipment all the way up.
I am really into this one, first i must overcome some barriers, won't take long.
If i overcome all those barriers and i can have all the stuff needed at a FAIR price and not lab ect prices.
First setup will be the expensive way (lab/experimental prices) to try, but my criteria is: i must also purchase and be able to buy those materials in bulk for production.
Sorry to say, how convenient it could be to experiment on/in a glass jar, i think the results would be to different: if i would start to make a prismatic cell due to the used surface areas and reaction of used materials.
I even look into liquid pond foil to make a comparison for hdpe containers, or casting, welding hot glue hdpe, you name it.
The cells will get tested on potential operating conditions. Even a puncture, short circuit, over charge and discharge, throw into fire and even take a shot at it, ideas will be also asked if the moment is there.
I forgot the name of the tread (I will find it)but there is someone one this forum that made a "automatic cycler" to test cells for their cycles.

Prinstons is nice, but as you stated not diy friendly and to costly, my starting point is Robberts with fallback to Princeton.

Quote from vspin:
I haven't seen the member videos. How have you come up with these figures? Robert stated that his razor cell was 10x8x0.8cm, and has a capacity of 2432mAh, and looking at Princeton's numbers, it's even better (if my calculations are correct).

If you look at his thumb and match that to a measurement it is clear the cells are thicker than 0.8cm.
If i am not mistaking he is from the uk, now a thumb and a inch are not so different but in mm it would be a inch is 25.4mm and a thumb is 22 mm.
In the capacity the electrolyte plays a big roll just as the surface area of the anode and cathode.
In one of his experiments (you got me there!) he was stating that he was discharging his cell with 0.5a an hour for 23 hours and 40 minutes.
That would translate to 10a in one hour at 1.8v, if my calculations are correct, we will get back on this one.
The cell can not give 10ah, it can hold 10a.
When i have complete some cells i can give precise numbers, discharges will be 200mah to 30ah.
Just like charging, i really am eager to see what they can handle max and it wont be much.
I think this is there major minus/weak point.

Quote from vspin,
How have you concluded that cells can only go 7 in series? Personally, I'd like to see you get to an operating range of 40-57V.

Weight, to stack them up to gain 48v you have to stack them 28 high, the pressure at the bottom one would be to much.
For 7 pieces on top of each other (12v) you won't have that problem.
If we take 10x10x2.5cm(estemet) cells they are 200 grams (estemet)each, i think 5.6 kilo pressing on the bottom one is to much.

Quote from vspin,
Where did you hear that? I'm trying to figure out a good standard charge, and discharge. In the optimization papers, a test cell was charged and discharged @ C/4 for over 6 months (600 cycles) "with coulombic and energy efficiencies of ~95% and ~70%, respectively," and no decrease in capacity.

The cycle is not a problem...over 10.000!! without degradation.
The "feeling" evidence is scattered in all of his videos and others: you can not start a car with it, you need to attach a capacitor ect.
This is also the reason why it did not work in cars around 1900 and 1970, remember back then (both area's)there was no need for energy storage, we would settle happy with lead acids if we had a off grid home.
Both of my parents remember being connected to the grid, have television, freezer, cooler ect. Hey.... when did we have the need for power storage? Take a look at siemens trollies before 1900, the first electric cars for groceries(or veg oil!), in a time we did not even have groceries stores(or diesel)...just saying.
4c would mean 40 amps an hour IF my calculations are correct in the first place! Tests will confirm.
But the discharge witc c4 beholds also other chemicals? not strait zcbr.

Quote from vspin:
If you do, I'd be your biggest fanboy should you share your project (and data) online. Smile

I will share everything, no problem!
To improve capacity it is not only zinc and bromine, especially if you want to have "dry"/gel cells and or with filaments such as that christmas stuff: oases? or polyester cloth.
Both have there different advantages and chemical challenges.
To be honest...I CAN NOT WAIT TO START, i think this clears it up a little?

Quote from korisan,
This particular design doesn't really have this problem. It will produce hydrogen if charged to high amps, but generally speaking this wouldn't be a problem. But, a vent for this reason, would be a good idea. Explosion of the "battery/cell" won't happen. It's the ignition of the H2 after it's come out of the cell into the atmosphere.

True to that, to H2, but they produce less than regular lead acid batteries.
At witch point it will produce hydrogen? 10 mah or 10ah? what can the cel take for storage and give for use, less then lead acid for sure.
How much saturation you must have to ignite with H2, sorry but never happened when i still had my vw2 on camping trips and walking in smoking.
But for a vented cell and closed cell that must really preform, it is also in the planning to test next to a lead acid battery to compare.
In a closed area with a electric ignition cap. Aldo this concept is not new, before i going to use it for storage i want every thing to be secure.

But first to get all the materials wanted(lan for experimenting and bulk!).
To much info i wanted to give, so its a short version, i hope you understand this jibberjat and respect my incompetent english
Thanks for sharing your thoughts, i really hope i will read more!

Thanks in advance, best
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#24
Its almost to simple to be true.
For a single blade cell, without anode or cathode(cous you actually don't need them) you need:
hdpe sheets:
https://www.voskunststoffen.nl/kunststof...dpe-zwart/
You can also cut up jerrycans or what ever, as long as it have that "2" in that "triangle" and it is NOT transparent.
hdpe carbon back filled
https://www.caplinq.com/linqstat-xvcf-20...ilter=5044
Graphite foil:
https://www.graphite-shop.com/de/folie-D...7-102.html
Oasis:
https://www.bloemschikmateriaal.be/basis...-met-20-st
Zinc Bromine 500g:
https://shop-lab-honeywell.com/products/...nc-bromide

17.00
65.18
8.70
18.95
106.

You can add as filler for 50% next to the oesis 50% carbon feld.
Carbon feld, its very expensive, probably for later experiments.
https://www.aliexpress.com/af/carbon-fel...0131002350

You can also add to this electrolyte:
Tert-Butyl bromide.
Poly ethanol glycerol.

When you decide to work with carbon feld its conductivity can be improved to let it soak and dry in a 2.5 m Tert-Butyl bromide solution.
Poly ethanol is also added (2% of total volume) to withstand lower temperatures and improve a little bit conductivity.

His battery design can host a lot of different chemicals.

In short how it works:
Prepare this two times:
Heat melt(home clothing iron 190c) a sheet of grafoil on a sheet of hdpm carbon, heat glue on another sheet of edpm carbon.
The graphite must be facing out.

Make your epdm plastic "ring" with a 2mm filler hole into it, and hot melt the epdm/grafoil on it, graphite must face out.
Fill it with cut to fit oasis and if you like carbon felt.
Take the other prepaid epdm/grafoil and close your case/box, graphite out, heat melt that one one top.
Fill this box with 1.75 m solution. (=~393 grams (ZcBr2) dissolved into a liter of distilled water).

This will give you a cell that can hold 1.85v and per squire cm 20ma
But that number can vary a lot, if discharge/charge is done with 500mah or 5Ah.
Tests will reveal this.

My total costs per cell will follow.

First i will order ZcBr from this alibaba seller, if this is not a success i will order what i found.

Edit: the seller from alibaba forgot to mention freight costs: $670 for 10 kg, i will do a local pick up for $100 for 500 gram.
When it is a success i could be wise to order 25 kg.

If it is in the first place allowed into country.

Any hints tips thought are very welcome, also purchase of materials.
I am looking forward to this project.
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#25
IF this works, BIG IF!
IF the stated/giving numbers are correct!
It could be half of the cost of lifepo.
But lifepo has 5000 cycles, they say zcbr2 has 10.000 cycles.
So it would be 25% of the cost of lifepo
......IF BOUGHT IN BULK(100kg min).....AND DELIVERED TO YOUR COUNTRY.....
I run into some problems.....sorry...but its me against the roberment....again...when it comes to environmentally friendly.
Maybe some help from Belgium, Germany or Poland? send me a pm, please, I pay and drive all the way up to Ribnik Poland from Hoorn in the Netherlands.(1230 km) just send me a pm if you think you can help
The costs would be 15 to 25% of the lipo ess.

I calculate with 20ma per cm2 and 10x10x2.5cm cells=100ml a cell = 55 euro cents for a complete cell: 1.85v at 2a, total costs.
It would be: 3.7v at 1 amp in znbr2 at 55 cents against 1.10 in 1a in lifepo4 3.2v
Shelf Life: znbr2 10.000, lifepo 5000, would be 27.5 cent in znbr2 against 1euro ten = lifepo4
Again that 20ma per cm2 can vary a lot: depending on the amount of electrolyte and the contact BUT above all, the charge and discharge amount, if keeping low, the cell can give ten times more than when you do a high drain, curios isn't?
Can self heal?
Don't need balancing??? if used as 28s1p for 48v.

With one kilo of 99% pure znbr2 you could make 2500ml electrolyte,(according to princeton's best price/watt ratio) for the best solution.

Holy grail? Smells like it. I would like to find it out, any help is welcome.
In the meantime ill try to get the znbr2

sended to quick, for propper gramatics... c ya tomorrow
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#26
Tomorrow i will receive my batch of ZcBr2, 500grams.
It's easier to buy guns and cheaper to buy cocaine......
Anyway in the limited time i had last week i did the following:
Read every paper i could find and printed some,  to get a impression of the type and behavior of the chemistry and cell.
The biggest difference is i am not going to make a flow cell with tanks attached to a membrane.
The "tanks" will be into the membrane.
Those so called "flow systems" are also easy to construct, but as a diy er i don't think and don't believe you want to walk those miles
Again this is easy to make if you know what you are doing with chemicals:

With the ZcBr2 you can create a basic electrolyte with more negative sides than positive sides.(con/pro's?)
I encountered/read in several papers (not the ones that were copied) the following problems:
Especially the self consumption = 5 - 15% a day every day the same, is a returning headache.
It would require a full charge once a week minimal to stay useful as a ess.
With the amount of sun we had in the last three months in the Netherlands....?!?!?!?(whole EU?) good luck.
For charge and discharge rate: max 0.5c, it simply can not take or give more.
Example for this self consumption 10% per day:
You will start at 10kw you lose 10% = 9kw left.
You start with 9kw you lose 10% = 8.1kw left
8.1kw - 10%= 7.29
7.29kw - 10%=6,56
ect, forgot what the name was for this interval, physics was 30 years ago...
It is the car that will never arrive.
This can be greatly approved with some additives and fillers apparently.
The space used for 10kwh of storage = if one cm2 can hold just 20mah (my guess: ~60-80mah) it would be 2.8 m2 and 60 cm high to obtain 48 to 50 volts.

This is one of the first things i would like to test:
This cells electrolyte is able to withstand overcharge, cous it is self discharging immediately when saturation level is reached, we will see by testing this.
They say you can discharge this type to 0v without damage or capacity loss.
This would basically rules out a bms, balancing system and/or a dedicated charger? strait on pv panel with a zener diode?
However a control device for visual check with resistors and led's at cell level would be in place? sinds the max volt of a cell is 1.85v.

What i would like to test:
Cell one:
Various capacity tests between the voltige span 0.5v and 1.80v ranging from 10mah to 1ah
This is going to depend on the cells area.(20mah per cm2?)

Cell two:
Overcharge 2v to 3v (5v)let it sit for 24h for several times.
Discharge to 0v several times.

Cell three and four:
cycle test, minimum 5 cycles at a day.

Cell five:
Will be charged and left alone for monitoring voltige.
Including short circuit when fully charged and at the end deliberately damaged

If enough electrolyte is over:
Cell 6 will be twice the surface area
Cell 7 will be twice as thick
If not enough over then those tests will be for the second round.

If those tests will be satisfying i will buy 2.5 kilo more zcbr2 and do some more tests:
repeat basically the same experiments with different fillers and chemicals.
and create a battery that can hold 12v a 7s config. 10x10cm.
Experiment with the solution of ZcBr2 from 1 to 4 molar solution.
Making high and low drain cells.
Try to rule out the self consumption or minimise.

Cell three and four will keep on running till they give up or they reached cycle 10.000.
Outcomes will be recorded in exls
Now i don't have mit's reachers money or equipment. so i will have to do it with a simple 2v charger and a zb discharger paper and pencil.
Any thoughts on this? to make it automated instead of manual?
Any suggestions for the first round of tests?
Or improvements, idea's?
Ideas/answers on my questions in this "paper"

Material list for the first experiments is stated in a earlier post.
Different chemicals and materials for the second batch of experiments will be posted, when i am at that point.
When i am talking in measurements they will be in metric! to avoid unit confusion.
End conclusion will be in metric and imperial.

To get a secure start, can someone confirm that i did not make a calculation error:
A 1.75 molar solution would be 393 grams (not grain)ZcBr2 dissolved in one liter distilled water.

Thanks for reading, it is a lot of text, and i really tried to keep this as short as possible.

Next week the build and the testing will begin.
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#27
(02-06-2020, 01:06 PM)100kwh-hunter Wrote: To get a secure start, can someone confirm that i did not make a calculation error:
A 1.75 molar solution would be 393 grams (not grain)ZcBr2 dissolved in one liter distilled water.


This is what I got using the molar mass of ZnBr2 listed on wikipedia:

225.198 g x 1.75 = 394.0965 g


Make sure that you add the ZnBr2, then add distilled water short of the 1 L mark, and completely mix/dissolve the ZnBr2. Then add more water until it reaches 1 L, and mix again. Opposed to mixing 1 L of distilled water with ~394 g of ZnBr2.


I'm so excited to see what you find!
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#28
Is 1 Mol solution or 1.75 Mol solution the best?
I have also seen 1.25 Mol used so, I have no clue....

Are you planing on trying different amounts?
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#29
(02-07-2020, 08:28 PM)Bubba Wrote: Is 1 Mol solution or 1.75 Mol solution the best?
I have also seen 1.25 Mol used so, I have no clue....

According to Princeton, a 1.0 M ZnBr2 electrolyte solution offered the lowest levelized cost of storage (LCOS) based on their cell configuration. However, an optimized cell configuration which improved electrochemical performance would benefit from a more concentrated electrolyte solution.
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#30
From all the experiments i read so far:
From all the solutions ranging from 0.5 to 4 m solution, 1.75 M solution would be the best LCOS.
However if you are short of storage space you could do 2.5 M solution.
A 1 M solution would give (in theory) 10-15 mah per square cm.
In all the papers i read, there were no clear schematics/table/setting or numbers for this.

But this is all theoretically.
I have a suspicion that if you are going to increase the solution you must also increase the height of the blade cell if you are not going to work with tanks.
The more stronger the solution is the more room you need to have for the crystallization of the zinc.
Up to the point where the zinc crystals and the bromine will contact each other again and begin the reverse process of self consumption.

We will find out

@Bubba, please share your experiments and findings here.
I am indeed planning to use different settings IF my first couple of experiment were satisfying.
In the second couple of experiments includes also combinations of cell height and different solutions.
Also adding some different salts/chemicals and fillers.

To make a 10kwh 48v battery you need 2.8m2 of space and 0.5m in height.
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