Energy storage 18650 up to 24kWh class Paragon, Powerwall

>>21280152 .
Unfortunately, but once the hydrogen has been ignited, this cannot be stopped other than by controlling the temperature in a large quantity of water. In this water the reaction will take place until the lithium is completely reacted. In Li-ION, the polymers are organic, which means that, in simple terms, they burn just like a plastic bottle.

speedy9 wrote:

I like your design......
...... why did you decide to go for such a, overall rather low, usable discharge current? Boosting the current to 500mA, which is typical for standard cells, is unlikely to shorten their life noticeably, and you will need fewer cells. For what it's worth, setting the discharge to 3.3 and the charge to 4.13V is a very good step. This undoubtedly has a positive effect on the life, as Li-Ion in particular "dislikes" discharging below 20% and charging to 100%.

Thanks for the good word .
These voltage thresholds are set experimentally and work best for these cells in terms of the efficiency of the whole storage and the temperature culture of the cells. And I did quite a lot of experiments during the first tests.
With current it is also so that there are moments of jerks and up to 600mA when I have to fiddle with a chainsaw in the garden and the saw cuts itself on some stick , or a large load such as 5kW goes on at home.
Of course, after filling the entire storage with cells, the average currents will still decrease to a level of 150-250mA , so the cells should work for years .
I don't care about reducing the number of cells - but just maximising the storage capacity, because that's where the tangible savings on bills come from, the less often I switch to "grid" the better for me .

These were secondary cells, or batteries. A charged battery will ignite readily when punctured. A discharged one will smoke slightly. The tests were conducted and documented by a Russian. Lithium ion batteries do not like overcharging. Nickel metal hydride ones, also tolerate it badly. However, in the case of nickel metal hydride, the only effect of overcharging is that the battery leaks and gases escape to the outside. The same is true of maintenance-free batteries, but there the lightning mixture escapes, so there is an explosion hazard. Batteries with liquid electrolyte, which are intrinsically non-flammable, can also explode after overcharging by splashing sulphuric acid around. This has been experienced by masters lighting a match to check the electrolyte level in a charged battery. Sparking crocodiles can also initiate the ignition of a lightning mixture.
I have not heard of alkaline batteries exploding, but it is possible that there is such a danger.

airman wrote:

Hi, Have you not thought to make a 15S ? I assume you have one of the Chinese hybrids that can charge up to 60v max which gives you charging the cell up to 4v you will reduce the capacity slightly but combined with the low current draw the life increases.

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No, sometimes apparently better is the enemy of good, overzealousness is worse than fascism , I would lose the possibility of a comparative analysis with other users who also use similar Li-Ion 14S magazines , not to say that the difference in cell efficiency between 4v and 4.13v would be significantly noticeable, and I care about the best compromise "performance"/"wear time".

Added at 39 [minutes]:

Janusz_kk wrote:

........
so you are still a beetroot to me for those words because it decomposes water which figuratively means it 'extracts' oxygen, so I was right........

Yes - you are right.
With all due respect, Janusz, please don't insult others because it's not nice, start your own topic "how to blow up and set fire to any battery" and there you can bludgeon all you want 24/24 with your observations on how to set fire to any battery, but please don't make a dustbin in my thread - go and have a rest.
An old maxim from kindergarten to remind you "whoever is called names - so are they".

LEDówki wrote:

....... Charged battery readily ignites after a puncture........

Same request, go along with Janusz to the arson thread so he has someone to argue with that he is right.
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The same goes for all the other potential "home-grown firefighters" .
Please everyone, however, here maybe focus on the possibility of improving the performance of such a depot, maybe on improving the design details etc. , believe that I really know exactly the potential risks, do not underestimate and try to embrace.
I've blown through "temi recyma" thousands of links and I know what I'm doing .
Because I will start reporting to the moderator, - and there will be shame .

remzibi wrote:

believe that I really do know exactly the potential risks

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I have my doubts about this, these are hundreds of individual Li-ion cells, any one of which could turn out to be faulty and cause an avalanche reaction effect.
For the money you spent you would have made yourself 14 kWh on LFP and forgotten you had storage.

Added after 1 [minute]: .

remzibi wrote:

I've rewired "temi recyma" thousands of links and I know what I'm doing .

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The specifics of Li-ion cells are fire hazardous. You can rewire and millions, but it will still be Li-ion.

pawciu-85 wrote:

remzibi wrote:

believe that I really do know exactly the potential risks

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I have my doubts about this.....

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And great, everyone can have what they want - that's what freedom is all about,
so I invite you to the thread "how to set fire to any battery"

remzibi wrote:

I therefore invite you to the thread "how to set any battery on fire"

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There is no such thread unless you set one up. It has not been known since today or yesterday how Li-ion cells behave in fire. I would not dare to keep such a "monster" in my house (cellar, garage, etc.), unless in a free-standing room, where it will not cause any damage if it catches fire and the fire brigade will flood it with thousands of litres of water.

pawciu-85 wrote:

.....Ja .......

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Thank you and appreciated for sharing your thoughts.

remzibi wrote:

pawciu-85 wrote:

.....Ja .......

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Thank you and appreciate

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You can bend your own theories. But you will not bend the laws of physics. It has already been confirmed that Li-ion cells are fire hazardous. You cannot change the construction principles and chemical properties of these cells. You can only take care of prevention and give your monster a lot of time and attention. As an experience ok. As usable energy storage - a complete mistake, considering the price and properties of LFP.
All industries including e-mobiliti are already abandoning Li-ion cell technology in favour of LFP.

pawciu-85 wrote:

....... It has already been confirmed that Li-ion cells are fire hazardous........

Yes I confirm, before I started building I studied the topic for a long time.
Thank you and appreciate you for sharing your thoughts.

And back to the topic .... have you considered DIYBMS ?

__Maciek__ wrote:

And back on topic .... have you considered a DIYBMS ?

Yes, but the degree of labour (time) involved in putting it together, plus the daunting cost, unfortunately disqualified it early on.
For a moment I also considered Dale, but in the end, price-wise and functionally, the JKBMS remained on the battleground as the most optimal choice for my application.

pawciu-85 wrote:

It has already been confirmed that Li-ion cells are fire hazardous. You cannot change the construction principles and chemical properties of these cells. You can only take care of prevention and give the monster a lot of time and attention.

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Any ignition due to a reason other than damage to the case by an external force (e.g. nailing, squeezing, nicking) will be preceded by swelling of the cell. These gases that cause swelling will lead to a rupture and at that point ignition will occur, exactly as after a nail has been hammered in. It would be possible to make a check on a 3D printer in the form of a U-shape (perhaps something like this can be bought ready-made), into which a correct cell would enter freely and a swollen one would not. If we assume that we have to check every year, we could, for example, check one column every month. And since there are 14, not 12, columns, this would make checking a little less frequent than once a year. And if it's once every two years, then either one column every two months or half a column every month, and then you're not as overwhelmed with antsy work than if you went through the entire magazine in one sitting. This will allow you to find and eliminate swollen links from the magazine fairly quickly and in time, so the benefit is not only reducing the fire risk but keeping the whole magazine in good shape.

andrzejlisek wrote:

........ You could make a U-shaped checker on a 3D printer ......

The subject of cyclic inspections is brilliantly handled by thermal imaging, fast easy and pleasant, even before the cell "thinks" to start swelling, thermal imaging catches it months before it does.
Mechanical inspection, with tools such as thermal imaging at its disposal, is out of the question due to its tediousness.
Suppose, however, that by some miracle the gases increase in pressure - the CID fuse of the cell will work, if it doesn't work, the cell will again be visible in thermal imaging.
If people had thermo control, accidents could be reduced to zero.
Fortunately, we live (I have lived) in times where thermal imaging technology is already seamlessly available "under the thatched roofs" , and I don't have to fiddle like I used to with such inventions https://www.elektroda.pl/rtvforum/topic2398928.html

remzibi wrote:

Yes, but the degree of labour (time) involved in assembling it, plus the daunting cost, unfortunately disqualified it early on.
For a moment I also considered Dale, but in the end, price-wise and functionally, the JKBMS remained on the battleground as the most optimal choice for my application.

I understand that this needs to be done 'at once', not very much can be done bit by bit as time and money allows.

Does the charging of the magazine proceed in the same way as the charging of a single cell, i.e. connecting the voltage corresponding to the whole with current limitation, or does it proceed in a different way, e.g. a separate power supply for each column with cells connected in parallel?

andrzejlisek wrote:

......
I understand this needs to be done "all at once", not really possible to do bit by bit as time and money allows.......

I would never fire up a warehouse without full control, so the 'partial' option is definitely out.

andrzejlisek wrote:

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Is charging the magazine the same as charging a single cell, i.e. connecting the voltage corresponding to the whole with current limitation.....

Charging is the responsibility of the inverter and in "buck" mode it is a normal, obviously defined CC/CV charger, "float" mode is such a defined CV containing within the defined "buck" range.
Balancing is the responsibility of the BMS, everything is user-defined, voltage thresholds, differences to start and balancing current, so those who want can really potentiate themselves and with the accuracy to thousandths of a volt . There is generally a mass of settings, current, voltage and thermal alarms, etc., to choose from.

remzibi wrote:

before the cell "thinks" to start swelling, thermal imaging catches it months before it does.

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Just wondering... have you ever seen a swollen 18650 cell? I'm seriously asking. Because I haven't. I don't think it's likely due to their construction that it would swell, because it swells from gases, and it's unlikely to build up so much that the cell would swell and the fuse would still hold.
And by the way, I'll add an example from my life with Li-Ion. Once my Liitokala Li-500 charger 'packed' over 9900mAh into a 18650 cell! That is, more than three times the nominal capacity. I haven't used it since. And, nothing happened, but the cell was very hot. Unmanageable in my hands. I should add that it did not leak.
https://www.elektroda.pl/rtvforum/topic3997917.html#20706340

You might consider adding a thermometer like this on ZigBee at the top, between each battery column: https://pl.aliexpress.com/item/1005006859951460.html
You will have continuous temperature monitoring in the app and alerts. The cost is negligible and the added security is there. Heat "goes" up, so if something bad starts to happen, the temperature will rise. When the alarm should occur would have to be tested experimentally. This could even be combined with an alarm siren .

speedy9 wrote:

........
Just wondering... have you ever seen a swollen 18650 cell? I'm seriously asking. Because I haven't......
...... I once had my Liitokala Li-500 charger "pack" over 9900mAh into an 18650 cell! ..... And, nothing happened, but the cell was very hot.......

No, I've never seen a swollen 18650.
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Anything that heats up over 40st when charging 700mA is rejected.
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For fast, accurate and authoritative temperature monitoring, only thermal imaging, temp sensors I have but it's "Bronze Age" technology compared to thermal imaging. By the time the heat from a cell, already averaged, reaches where the sensor is, thermal imaging will catch every 0.1 deg.C months in advance and immediately when the anomaly becomes apparent.

remzibi wrote:

For fast, accurate and authoritative temperature monitoring, only thermal imaging, temp sensors I have but this is "Bronze Age" technology compared to thermal imaging. By the time the heat from a cell, already averaged, reaches the location where the sensor is, thermal imaging will catch every 0.1 deg.C for months in advance and immediately when the anomaly becomes apparent.

You're absolutely right, but thermal imaging inspection requires an approach every time, and you have continuous monitoring. That was just the idea that came to me, I don't know how it would work in practice.

remzibi wrote:

Anything that heats up at 700mA charge over 40st is rejected.

This heating is due to the internal resistance. Unfortunately its measurement in the Lii-500 is not very accurate and varies between channels. The Lii-600 has the same problem. I tried pairing high-current cells for a remote control boat in this way and unfortunately it did not pass the test 100%.

speedy9 wrote:

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You're absolutely right, but thermal imaging inspection requires an approach each time, and you have continuous monitoring. That's just the idea that came to me, I don't know how it would work in practice.......

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In practice, you approach with a thermal imager and see the slightest anomaly, while monitoring is supposed to be continuous and you don't see anything for months and you don't know what's really going on - unless it's only when it starts to heat up seriously (which is a bit too late), so this kind of monitoring sucks (and it's used because there's no other method and it's a bit expensive), because it works with a significant delay (we're talking about a scale of weeks), which is also the cause of potential problems.

I wasn't suggesting abandoning thermal imaging, but rather as an add-on. Thermal imaging obviously does the job, as you write.

I like the design, the workmanship is very tidy and well thought out, it's clear you've already spent a ton of time, and still the selection of the remaining links. I have a question in connection with the approaching winter - your storage is in a heated room, did you somehow solve this issue? I don't think rechargeable batteries like the cold.

franyo_z wrote:

...... Your storage is in a heated room, have you somehow solved this issue? The batteries don't seem to like the cold.

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Yes, cells do not like frost, in this concrete room, the temperature generally never drops below 15st C.

cefaloid wrote:

Of course you don't like to go on holiday and during the day when charging currents are highest - you work from home. And you have a way to go to measure this every day with a thermal imager.

Well cool. Only in my humble opinion the warehouse should be unmanned, not that you are tethered to control whether by thermal imaging or whatever. And when you have time to yourself you think on holiday whether your storage facility is by chance overheating.

With thermal imaging you can also make an automatic, although I don't know if its price will be adequate for the whole storage. I don't know how many cells you are analysing per image (the more, the cheaper the solution), but making such an image analysis, for detecting the crossing of a temperature threshold, is not a big problem. As a last resort, you could imagine one camera and some kind of system to move it (two motors - X, Y, like in a plotter). Unfortunately, increasing the resolution of the IR sensor equals a much higher price of the camera, so even a small resolution + panning will come out reasonable - e.g.: https://kamami.pl/czujniki-podczerwieni/11879...e-with-40pin-gpio-header-o-5906623427956.html. It is possible to buy a 32 x 32 pix, 32 x 24 pix solution for less than 200zl, but I don't know how to get along with it (some API, DLL would be useful), as these are usually ready to be plugged into a phone via USB.

smiga wrote:

.....Finally, you could imagine one camera and some system to move it (two motors - X, Y, like in a plotter).......

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I've previously provided a link here with a prototype of such a solution, but I won't elaborate on it https://www.elektroda.pl/rtvforum/topic2398928.html , which doesn't mean someone else can't pull it off

Added after 5 [minutes]:

cefaloid wrote:

..... And you have as you go to measure it daily with thermal imaging.

pawciu-85 wrote:

And when you have time to yourself, you think on holiday whether your storage unit is accidentally overheating.

Yep, this is where I think I'm diagnosing obsessive neurosis, go ahead and talk it out, it brings relief .
For calming neuroses, no , you don't have to go anywhere every day (but you can if you have something wrong with your head) and you don't have to think about something all the time (but you can if you have something wrong with your head). As much as possible you can think all the time not even about your - but about my storage (and imagine it in your bedroom) , that's what this thread is for to provoke thinking about energy storage and the consequences of climate policy .

Added after 24 [minutes]: .

pawciu-85 wrote:

..... Only in my humble opinion, the warehouse should be unmanned, not that you are tethered to inspection whether by thermal imaging or any other way.......

100% of mankind would like it that way, but unfortunately all the warehouses available today have very sophisticated monitoring and control systems, if it doesn't fit - you give up the warehouse, but your neighbour won't - so you can already start thinking about it all the time (if you have something with your head) .

remzibi wrote:

but unfortunately all warehouses available today have very sophisticated monitoring and control systems, if it doesn't fit - you give up the warehouse

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I built my warehouse in such a way that I can leave it unattended for a year. A fire-separated room. I have all the information online or via sms. Cell temperature, room temperature, BMS errors and communication via CAN with the inverter, which physically disconnects the warehouse from the inverter in the event of currents, voltages or BMS errors being exceeded. Smoke and temperature detectors mounted inside the rack with the warehouse alert via SMS and automatically disconnect the warehouse from the inverter; in the event of any anomaly, I can also disconnect it myself by sending a single SMS message. IP camera from which I have an on-line view of the warehouse. A fixed fire extinguishing unit ( SUG ) for HFC 227EA gas is about to appear.

Finally, the technology for making the cells. LFP. Safe, and relatively fire-safe.

pawciu-85 wrote:

....My warehouse is so built that I can leave it unattended for a year......

Bravo, cheeky boy, and that's what you call an elaborate system of control and supervision, we all aspire to that ideal .
You can see right away that you're still thinking about it, and don't stop .