diy solar

diy solar

Last fire.. :-(

In the last pictures, why are the studs different diameters and different lengths? Sometimes on the same cell and sometimes on different cells?
Yes.

Welcome to Thailand and first month's of Covid postage service.

In Thailand at the start they desinfect all parcels from China with....
Alcohol spray. Almost no address survived, faded away, not usable.
After this 21 days quarantine.

AliExpress blocked my account for 6 months, as I claimed too many parcels that never arrived.
Only after written statement of Thai postage service about their desinfect method and loss of addresses, my account was restored.
Many parcels never arrived and never got refunded.

My real life situation.
Some hardware shops have some grub screws, a few.
Thailand is a total mess with Mm and inch.. not uncommon to find M6 studs and only 1/4 inch nuts.
That took me a long time to get used to.
Now I know, just go to the next shop, they might have it revested...
And this is not a Joke!!

Bangkok area, for sure different.
650km from BKK... I can't go to buy there. Besides lockdown, no inter provincial travel.

Simply using what I could get my hands on during a bad situation.

Found out quickly that the screws provided where bad news.

I used M6 bolts for a while
IMG_20210727_122728.jpg

That worked, but obviously can't use Loctite....

IMG_20210727_122739.jpg

My collection of grubscrews, none enough for all the cells (160 studs)

As result of a few remounts and replace of BMS wires, many threads where lost.
39 to be exact.
Different thread shows the repair.

Some could be fixed with helicoil (tap to M7) some times that tap would fail in the soft aluminium.
then M8 was the next step.

Challenging times we live in.
Rural Thailand on its own is already challenging to find usable and quality products.
Many times I waited for a trip to Holland and went to the local hardware store to get what seems impossible to find locally.

Ox-guard? I forgot how much exactly..$60 or so for a tube.
JB weld was $45 from China
Thanks to @Just John the stuff to repair the threads arrived from the states.

I've shown the pictures of $160 Amazon asks for shipping and handling for a tube of glue... Of $10 bucks.

I'm relieved that this struggle has come to an end.
Cascade of events, location and environmental changes.
And obvious me in the center juggling to keep the stuff together and working.

Some one wrote : "the best advice was to take pictures"
I hope that the best advice people can take from this is preparing.

You should be prepared for electrical fire.

I was, and it saved out house.
Not fully prepared, no hand held fire distinguisher.
Now we do have.

If anything, please..
Be aware that it might go wrong.
Even professional builds.
There are EV that go up in smoke without accident, spontaneous.

Be prepared for it.
Your storage location safe enough to withstand several hours of fire and smoke detector alarm to warn you and family.

Take care and stay safe!!
 
Yes.

Welcome to Thailand and first month's of Covid postage service.

In Thailand at the start they desinfect all parcels from China with....
Alcohol spray. Almost no address survived, faded away, not usable.
After this 21 days quarantine.

AliExpress blocked my account for 6 months, as I claimed too many parcels that never arrived.
Only after written statement of Thai postage service about their desinfect method and loss of addresses, my account was restored.
Many parcels never arrived and never got refunded.

My real life situation.
Some hardware shops have some grub screws, a few.
Thailand is a total mess with Mm and inch.. not uncommon to find M6 studs and only 1/4 inch nuts.
That took me a long time to get used to.
Now I know, just go to the next shop, they might have it revested...
And this is not a Joke!!

Bangkok area, for sure different.
650km from BKK... I can't go to buy there. Besides lockdown, no inter provincial travel.

Simply using what I could get my hands on during a bad situation.

Found out quickly that the screws provided where bad news.

I used M6 bolts for a while
View attachment 57821

That worked, but obviously can't use Loctite....

View attachment 57822

My collection of grubscrews, none enough for all the cells (160 studs)

As result of a few remounts and replace of BMS wires, many threads where lost.
39 to be exact.
Different thread shows the repair.

Some could be fixed with helicoil (tap to M7) some times that tap would fail in the soft aluminium.
then M8 was the next step.

Challenging times we live in.
Rural Thailand on its own is already challenging to find usable and quality products.
Many times I waited for a trip to Holland and went to the local hardware store to get what seems impossible to find locally.

Ox-guard? I forgot how much exactly..$60 or so for a tube.
JB weld was $45 from China
Thanks to @Just John the stuff to repair the threads arrived from the states.

I've shown the pictures of $160 Amazon asks for shipping and handling for a tube of glue... Of $10 bucks.

I'm relieved that this struggle has come to an end.
Cascade of events, location and environmental changes.
And obvious me in the center juggling to keep the stuff together and working.

Some one wrote : "the best advice was to take pictures"
I hope that the best advice people can take from this is preparing.

You should be prepared for electrical fire.

I was, and it saved out house.
Not fully prepared, no hand held fire distinguisher.
Now we do have.

If anything, please..
Be aware that it might go wrong.
Even professional builds.
There are EV that go up in smoke without accident, spontaneous.

Be prepared for it.
Your storage location safe enough to withstand several hours of fire and smoke detector alarm to warn you and family.

Take care and stay safe!!
These circumstances are unfortunate. It is also unfortunate that the laws of electricity don't care about circumstances. Thanks again for sharing your story. it is great that you had a good fire alarm/warning system. Glad it was only property and not life lost.
 
Finding the hardware is frustrating and time consuming in Thailand, there is no one stop shopping, everything is available but just not easy to locate and the language barrier only makes it worse,

May I ask, previously you mentioned having two banks, a 280Ah and a 150Ah in parallel connected to bus bars, what would prevent the larger bank from dischargeing into the smaller, usually in an arrangement such as that the use of 2 BMS's would be utilized to disconnect when any single cell drops below a critical value? Forgive me if I missed an explanation but the rather long posts may have clouded my thought process.

Rationale behind the question is to possibly come up with cause, you certainly don't need this to happen again.

Having the same challenges I managed to produce a reasonable system which has worked well fo 3 years, not perfect but functional, I'll aujojbgkycz3.jpg
 
Having 2 different capacities on a system, eg 280Ah (560) @51.2v, 152ah @51.2v and 304Ah @51.2v would result in 1016Ah total capacity.

Discharge will go Equal, it doesn't care if it's 100 or 500 or 1000A, it's parallel, what accumulate the capacity.

That's good.

If one would have 10 X 280Ah, and one cell would not have 280, but 260, the set of that one cell would be 260Ah.
Not all 10x 280
So 2800 to 2780 due one (or more in that S16 pack) cell degradation.

If it would need all the same, the pack would reduce to 2600..
Luckily that's not the situation.

Obviously there will be some discharge from lower resistance packs to the higher resistance ones.
(Or other way around)

It's not like lead acid where the Failing battery keeps discharge the whole pack.
It stays stable.

Also the reason why with many small cells in series and parallel (like e-bike) on can fail without losing the whole pack.
 
When dealing with any lithium battery bank one has to think voltage at a cellular level, not at the overall bank voltage, yes theroitically the two unequal capacity banks in parallel will discharge at equal overall bank values but not necessarily equal cell voltage.

Without individual cell control in the lower end of the discharge curve, particularly in a top ballanced bank a single cell could be overdischarged whilst the ballance of cells are at a low but safe value and since you mentioned a low voltage shutdown this came to mind.

What happens when the larger bank, with a higher potential difference discharges intio a smaller bank with a failed cell, is something I can't definitively answer, but in my 40 years of experience in the electrical industry, much of which involved life saftey, taught me, is in abnormal conditions the rules change, electrons find their way from the highest potential to the lowest through any path available. Having excessive paths of potential failure only adds to the possibility of failure, this is in reference to the cell balancers, which are for the most part unnecessary.

Not using a BMS is akin to not using seat belts in a car, it's a calculated risk being taken, understandably you had some negative BMS experience but there are many successful installations using them. Personally I think it would be wise to rethink the strategy as it's obvious something went wrong, the cause of which may never be determined, but after reading this thread and seeing the pictures, there is a lot of room for improvement in my opinion.

My comments are intended to be constructive, if others live in the same house where the battery is located, their life safety is dependent on your decisions, safe practice is the goal I'm sure most are aiming for, I hope you understand.
 
Biggest problems after spending several hundreds of dollars on purchasing BMS, they are CRAP!!
And fail In a really short time.
Daly S!cks bigtime, including their support.
Of both conclude it'd defective, why need to spend $75 on return to get $150 back? It's totally epoxied....

Hence the desision to use the DiYBMS, build my own as the quality I'm able to purchase is CRAP!
(April/may 2020)

Monitoring on cel level always took place with my 2 active balancers, same company as now have my Bluetooth active balancer BMS, Jikong.
With their app I watched, probably 10-15 times a day the individual cell voltages

I wrote, and write again that I looked at 07.30, battery level too low to start the inverters, not yet 49v
Voltage of the individual cells between 2.9 and 3.0v.

I totally understand how people need to find a reason and it works for them to think a cell was over discharged.
I know that it didn't.

It stopped at 48v, with a set constant being kept in balance, not just by burning at the top, but "24/7".
Imbalance was within 0.15v
No computer BMS doesn't mean that the individual cells where not monitored.

I don't like the top Ballance burn of option like Will is
For a lot of reasons.
For one the availability of sunshine!

In the Netherlands it's not uncommon to have a month and longer gray.
So gray that people get depressed and need light therapy to keep a bit a happy mood.
Gray is rain. Soft, harder, a lot, or a little. We have quite a lot of different words for different intensity of rain.

I guess to much from home in my mind... But with it.
The knowledge that a battery can float months between 10-70% before ever having enough sunshine to top charge and balance.
Solar panels should be enough to cover peoples needs, not overproduction beyond reason.
With my 14.5kw solar, during (light) rain at noon we still make 1000-1500 watt about 10%

My experience with my new, highest rated EVE cells (yeah, the bad luck batch) is that they don't keep days/weeks balance, and regularly need adjustment.

everyone building on his or her experience, in his or her setup and environment.

Bad Eve's and failing BMS'ses during Corona time where parcels litterly took months, where it used to be days/weeks.
My max, 152 days delivery time.

With it, my desisions made to the best of my ability.

Perhaps not yours at this time, and probably also not mine.
Corona crisis and with it the impossibility to order online, and local hardware stores who have just about nothing..
one does with the materials on hand.

Different times, different desisions.
If anyone want to question them, put yourself in my position and offer a better solution then I did choose, that was available at that time....
They're in for a real challenge.
You cant break iron with bare hands
Litterly translation from a Dutch saying.
English use :
I can't bend space and time.
Where time is a funny one in this perspective :)

The batteries where monitored, roughly 16 out of 24 hours, each hour.
Everything that went close to the top or bottom was dealt with accordingly.
Stop/reduce charge or stop / reduce discharge to match the remaining day/ night time.
And for over discharge, inverters stopped at 48v.
That makes absolutely sure that non of the cels would have been below 2.0v.
They where "recharged" using the higher voltage cells. And with a few hundred watts at nighttime (150-250w), enough time to compensate.

I appreciate all the thoughts where the problem was.
It never was more unsafe then the day I received my bad batch of 152Ah cells
Before this was a certainty that it was bad.. it was in use for 6 months...
And with it..
How bad can it be if I can use??

That last question is now answered.

@Will Prowse made a video over bloated cells that he strongly recommend to throw away and never use.
With my experience till that time, I challenged that statement, all seemed to be fine, yes?
Turns out you are right Will.
Bloated cells are not safe.
All LiFePO4 cells aren't safe to start with, having them bloated already tips the scale towards the danger side.

Having no BMS never put my family in danger.
Thrusting Daly BMS did.
There are a few videos out there with fused mosfets from Daly BMS that overcharge the cells way beyond safety.
Contractors are so much safer.
Sadly.. Chargery was out of stock, as was the Ant BMS.
(Who I tried to order first, before I received the pre-mature launched active balancer BMS)

Bad Luck magnet isn't only things that fail, often the inability to obtain quality products.
And no, $1000 for S16 Batrium.. that was beyond my reach.
In the end, I spend a multitude of this on BMS, and now have 100 cell modules and 10* controller boards of the DYIBMS..
48 of the cell modules will be placed on the BYD, together with the Jikong.
2 BMS don't need to fight eachother, they can work together.
Both doing their own thing based on the readings.

My Jikong BMS can not control my 3 X contactor to stop (partial) charge.
Not can it control my main 400A contractor that separates the battery from the 3 inverters.
It absolutely still can do its own thing, monitoring, measuring, active balancing.
And if it's not enough, the DIYBMS can help burn off excess for a few minutes, or tell the Contactors to disconnect.
Yes, the charge controller should take care that it does not overcharge.
Sadly, they are known to fail.
You just had some insight in my normal strain of luck..
I need to prepare for it to fail.

And, in case of fire, my smoke detectors make not only sounds, also have relay.
They stop all Contactors.

So... Safely first!
Second and third.
 
When dealing with any lithium battery bank one has to think voltage at a cellular level, not at the overall bank voltage, yes theroitically the two unequal capacity banks in parallel will discharge at equal overall bank values but not necessarily equal cell voltage.

Without individual cell control in the lower end of the discharge curve, particularly in a top ballanced bank a single cell could be overdischarged whilst the ballance of cells are at a low but safe value and since you mentioned a low voltage shutdown this came to mind.

What happens when the larger bank, with a higher potential difference discharges intio a smaller bank with a failed cell, is something I can't definitively answer, but in my 40 years of experience in the electrical industry, much of which involved life saftey, taught me, is in abnormal conditions the rules change, electrons find their way from the highest potential to the lowest through any path available. Having excessive paths of potential failure only adds to the possibility of failure, this is in reference to the cell balancers, which are for the most part unnecessary.

Not using a BMS is akin to not using seat belts in a car, it's a calculated risk being taken, understandably you had some negative BMS experience but there are many successful installations using them. Personally I think it would be wise to rethink the strategy as it's obvious something went wrong, the cause of which may never be determined, but after reading this thread and seeing the pictures, there is a lot of room for improvement in my opinion.

My comments are intended to be constructive, if others live in the same house where the battery is located, their life safety is dependent on your decisions, safe practice is the goal I'm sure most are aiming for, I hope you understand.
with lifepo4 prismatic, regardless of capacity, voltage curve stays the same. this means at "full" capacity, a single cell voltage is 3.65 (whether 280ah or 150ah). electrical flow requires a difference in electrical pressure (voltage); therefore, if there is no difference in pressure then no current (or very little) will flow between 2 parallel-connected cells or batteries (regardless of capacity).
 
For my first build I used a Shenzhen Battery Bodyguard ordered to specifications submitted to their engineering department, it is far more robust than what I've seen on Aliexpress with dual 8M screw terminals rather than pigtails. That BMS I consider the primary, to provide a second layer there is a Chargery to manually disconnect should the electronics fail on the prime.

The Chargery, in concept, is actually a good design, it is what I refer to as a passive BMS, not physically involved with charge/discharge and if wired to a NO contactor, fail safe, it is however primarily designed for EV applications but still useful in offgrid.

The second build has a Daly, which has been faultless, but I did order a current rating double the demand, I also switched to CALB cells, they are far better in quality coming with a factory test report and less expensive than the no name cells I first bought, $134 per 200Ah cell.

My orders from Aliexpress have all come through without major delay over the past year, at the beginning of the Covid scare, first 6 months of 2020, I didn't bother,ordering, knowing there would be delays.

The image is of the Battery Bodyguard BMS 930719247.png930719247.png
 
with lifepo4 prismatic, regardless of capacity, voltage curve stays the same. this means at "full" capacity, a single cell voltage is 3.65 (whether 280ah or 150ah). electrical flow requires a difference in electrical pressure (voltage); therefore, if there is no difference in pressure then no current (or very little) will flow between 2 parallel-connected cells or batteries (regardless of capacity).

I'm in agreement with the theroy you've provided, this would be the case in normal conditions, however if a single cell fell below a fully discharged value, the load was disconnected then the larger bank cascaded into the smaller bank, minus the failed cell, I'm unsure what the reaction would be, other than to say it would not be a normal condition and given the multiple paths available, anything could happen.

Unconventional arrangements may result in unconventional results, is what I'm alluding to, following known practice is usually the safer path, at least that's what I believe, choosing to diverge on individual theroy of operation may result in unforeseen problems, such as a battery meltdown.

Forums are an extremely difficult platform to diagnose a problem, there are many disadvantages, not being on site, disclosure of the operator and self preservation to name a few, we can only offer possible causes and the ping pong responses only add to the communication deficit.
 
I'm in agreement with the theroy you've provided, this would be the case in normal conditions, however if a single cell fell below a fully discharged value, the load was disconnected then the larger bank cascaded into the smaller bank, minus the failed cell, I'm unsure what the reaction would be, other than to say it would not be a normal condition and given the multiple paths available, anything could happen.

Unconventional arrangements may result in unconventional results, is what I'm alluding to, following known practice is usually the safer path, at least that's what I believe, choosing to diverge on individual theroy of operation may result in unforeseen problems, such as a battery meltdown.

Forums are an extremely difficult platform to diagnose a problem, there are many disadvantages, not being on site, disclosure of the operator and self preservation to name a few, we can only offer possible causes and the ping pong responses only add to the communication deficit.
Oh im not trying to diagnose. There's no mystery here. I was just iterating a law of electricity, and that is electricity requires a difference in electrical pressure in order to flow. (tidbit courtesy of Bob D owner of RSD academy, findable on youtube).
 
Dear fellow enthusiasts!
I periodically read the forum. And I have noticed several disturbing cases about combustion and/or thermal acceleration of large-capacity cells.
My experience leads me to the conclusion that many of us ignore the need to carefully insulate and protect the exposed live parts of our installations, as well as the fact that the aluminum housing of the prismatic cells we use is plus-plus. Many people make our battery enclosures/boxes out of metal. This is especially true for mobile rigs, campers, etc.
There is a short circuit of the cells and thermal runaway. Which people often call a fire.
Please be very careful to insulate the cells between themselves and the metal enclosure, which has contact with the minus (grounded), as is often done on autos. (Minus to ground).
For example, my battery will stand in the basement of an apartment building, and I very carefully insulate the cells between themselves, and the entire battery and the iron rack with 0.5 mm thick fiberglass.
I also find it necessary to make screens on top of the cell battery, and on the open BMS Seplos, which I also plan to use at my place.
To avoid such incidents.
Be careful and prudent, and God bless you!
 
Dear fellow enthusiasts!
I periodically read the forum. And I have noticed several disturbing cases about combustion and/or thermal acceleration of large-capacity cells.
My experience leads me to the conclusion that many of us ignore the need to carefully insulate and protect the exposed live parts of our installations, as well as the fact that the aluminum housing of the prismatic cells we use is plus-plus. Many people make our battery enclosures/boxes out of metal. This is especially true for mobile rigs, campers, etc.
There is a short circuit of the cells and thermal runaway. Which people often call a fire.
Please be very careful to insulate the cells between themselves and the metal enclosure, which has contact with the minus (grounded), as is often done on autos. (Minus to ground).
For example, my battery will stand in the basement of an apartment building, and I very carefully insulate the cells between themselves, and the entire battery and the iron rack with 0.5 mm thick fiberglass.
I also find it necessary to make screens on top of the cell battery, and on the open BMS Seplos, which I also plan to use at my place.
To avoid such incidents.
Be careful and prudent, and God bless you!
As I recall, some cell cases are positive, and some are negative, and it depends on who manufacturers them.

This on its own can cause a big issue if you assume the case is negative and it isn't, and don't accommodate this.

But other than that you're absolutely right. You need to ensure each cell is electrically isolated anywhere other than the appropriate terminal connections.
 
When we build a pack with aluminum cased cells we use Garolite G10 between each cell, then use aluminum or G10 end boards to prevent swelling. These cases are live and the PVC wrap is joke and about as robust as 1 ply toilet paper.

The only time we saw a failure of this magnitude, in a DIY build, the wiring looked about the same, a Mama Mia's special, and there was also no BMS for protection. The BMS had been disconnected due to "annoying beeps". Based on the report from the delivery skipper, battery voltage kept dropping until at the last glance by the Captain it was at 10.6V. Sorry, but I will also say there is no excuse for wiring like that. Two hours, a bit of patience and all that wiring could have been neat, tidy, chafe insulated and then it would not even be a topic of this discussion. If that were a boat you'd never pass an insurance survey. It could have been done, you chose not to.. Your bank your choice but you need to understand that your wiring was going to be a topic of discussion.

In the end one single cell had reversed polarity at the bottom and the others in parallel kept dumping energy into it when he had started the 170A alternator to try and get nav lights working again..

Why did it fail like that? Horribly matched cells for both capacity and internal resistance. "but they were A grade". Nope, they just told you they were, as most do these days... When that one cell fell off the low voltage cliff the others still had enough left in them so they did not all fall off the cliff at the same time. Just one bad cell can make a real mess. No BMS, no protection. These toy BMS's from China are just that, toys. They do not have anywhere near the capability (mA of shunting at best) to keep large banks in balance, especially if you bought the typical AliExpress "A grade" specials we sell all too many of.

All I can add on active balance modules is this; if you need active balancers, your cells are not of sufficient matching to be used together. If they are drifing that much after an initial top balance yu need to remove the bad cells and move on. Legitimate EV grade cells (not the phony "A" grade junk marked on AliExpress) can go hundreds and hundreds of cycles and never need balancing. They should match to less than 1% for Ah capacity and IR should be near spot on after a 24 hour rest from a parallel top-balance. We refuse to build a pack from cells that vary any more than that. We prefer a 0.5% for Ah capacity cell to cell, and there are cells out there that can do that, but you won't find them on AliExpress. We physically capacity test every single cell we build a pack with.

Thank you for being honest, a LOT more of that is necessary in the field of LiFePO4 (not just DIY either) and I do get a chuckle every time I hear someone repeat "LiFePO4 is perfectly safe". Just be glad you're on land a were not on a boat when this happened..!
 
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Dang man, hate to hear about the fire but glad you lost only the battery as it could've been much worse. Everyone starting out in this DIY world needs to read as many of these fire threads as possible because I'm afraid we're living in a "I can do that, I just need to watch a couple YouTube videos" world, at least here in the U.S. Good for you about the new packs and hoping for years of trouble free service.

One thing this has caused me to ponder, I'll add....you talk a lot about the posts/screws and how the factory makes these cells to have connections "welded" on and I think this is a very important consideration. It's normally a Middle Man that drills/taps these cells for posts, and it's often done by hand. Who's to say that one of the cells got drilled a fraction too deep. With making tight connections, that couldn't easily wear through in time and may very well be the source of the problem. Something to think about anyway. Stay safe over there!!
 
I guess you hit the nail right on its top...
Smaller ones still do.

20Ah, yeah, the charge/discharge rates aren't that special, and you can get away with a higher "error" rate.
280Ah.. 14 times more powerful, 14x less room for errors.
And now not Eve but some "garage dude" drillls the holes and taps the thread.
With all the pictures of skew threads and undeep...
For sure not a real professional.

More cells increase the complexity also a lot.
4 is "easy"
8 more complex
Try 48 cells....
 
I guess you hit the nail right on its top...
Smaller ones still do.

20Ah, yeah, the charge/discharge rates aren't that special, and you can get away with a higher "error" rate.
280Ah.. 14 times more powerful, 14x less room for errors.
And now not Eve but some "garage dude" drillls the holes and taps the thread.
With all the pictures of skew threads and undeep...
For sure not a real professional.

More cells increase the complexity also a lot.
4 is "easy"
8 more complex
Try 48 cells....
complexity is only slightly increased. That's 3x 48v batteries in parallel. or 2 in parallel and a hot spare sitting at 1/2 soc? The key is not to increase complexity by mixing cell types or cell capacities as well as to make sure your wiring and crimps are clean and insulated.
 
Lol
If you want to build it that way, yeah.
Make 3 separate packs of S16, and keep the simplicity of only series :).
3 X BMS...

Or make real parallel.
3* 3.2v
16* 9.6v
As what P3S16 does imply.

If you want to believe that my crimps where not clean and insulated, me my guest.
I know better.

If you want to believe that 2 sets of P3S16 152Ah ( 456Ah) and P2S16 (560Ah) is a problem, sure do!
That idea isn't based in science, only fear from lack of knowledge.

While some might think I'm picking a fight here, what you write above is (in mild words)
That my crimps are worthless, dangerous, bare open wires and for sure the source of fire.
That mixing capacity joining the same bus-bar is dangerous and stupid.
And that you don't understand what parallel really is in LiFePO4 setups.
That's my translation from what you are writing.

Sure.
Any wire used should be crimped correctly, should show no bare copper and while for some 4 wires look complex, and 320 will make their brain fry, the number of wires doesn't increase any danger.

Building packs of 4,8 or even 16 in series isn't as complex as building parallel.
What is NOT just 2 strands of series in parallel, but each cell is parallel.
Yes, 2 in serie is 6 cells, 3 serie is 9 cells, 4 in serie is 12 cells.
All joined together, one square of 12 cells with 12v.

Or, like my situation, original setup: 48 cells.

Imagine that one thread fails.
6 cells , 11 studs maximal need to be untighten, nut removed, busbar.
Then uncompress the 48 cells, take out the one that failed the thread, replace that cell (with same capacity) and put it back together.
While doing this, one of the 11 studs that first held..
Now fails...
And the whole thing starts over.

If you wonder how threads fail...
You haven't been in this forum long enough.
They aren't strong and a few remounts are enough to make them weak as a pack of soft butter.

If you ask: " why don't you use studs instead of the screws provided by the seller, use Loctite red with primer?"
Guess how that knowledge is wide spread in this forum...

Before knowledge is gained, there first is failure.

Sharing failure working together to find solutions to prevent this in the future and repair the issue is what makes this forum the source of knowledge it is.

Telling that my crimps are bad, that in your eyes I'm mixing 152 and 280 cells in a single serie strand (as you didn't undersood yet what parallel is) is reason for a fire.

I guess your crips are your reference point?
And your battery setup as it's a frankenpack and you are afraid it will catch fire because of it?
Please share!

And please, if you see a bare wire or bad crimp that isn't safe in the pictures I provided, also zoom in, and do share.

Yes, crimps should be good and safe, no bare copper.
No bare ends of the wire but safety first.
Good thing I only built like that.

It never hurts to keep reminding people how important that it.
 
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Lol
If you want to build it that way, yeah.
Make 3 separate packs of S16, and keep the simplicity of only series :).
3 X BMS...

Or make real parallel.
3* 3.2v
16* 9.6v
As what P3S16 does imply.
I fear this may be part of where your packs went wrong. yes, that is 3 BMS. it is highly important that every cell is managed and that you know what every cell is doing. if you start adding parallel then series, it is doubly important to know what each parallel set of cells is doing. furthermore, yes it is more BMS but it is also redundancy. If a battery malfunctions, it can be removed from the system, but the other battery or batteries can keep the system running even if at a reduced capacity. Repairs can be made offline and the battery returned to service when it is safe to do so. This reduces risk of fire.
 
Having 3 or 30 packs in parallel instead of 30 cells in parallel has its advantages and downsizes.

The one isn't more dangerous then the other.

Most packs build with small capacity cells are parallel.
My E-bike pack has 12 parallel, and one BMS
If one cell fails, the whole pack is reduced capacity, 8%.
No maintenance is needed, no replacement.

And, we start out with the wish, cells don't fail on regular basis.
Most cells in a pack don't fail.
They seldom do.

Sure, prepare that one will fail, and build on this, section it.
Not S16 only sets of S4
And..
20 sets of S4 making a 48v setup.

Being loose sets, each set is potential a risk.
BMS fail more often then cells do.
A lot more.

Especially the higher capacity ones.
20-50A, dumb BMS, they last ages
Above 100A?
Follow the forum a while.
I have 3 on my name.
One died in 3 days. Jikong pre-mature launch.
One after 3 months dumb Daly, and hell Froze over before that warranty was honoured.
Third one didn't start at all (Smart Daly), and I did not start the fight as I have more important things to do with my limited energy.

So just shifting the risk to a part that fails more...

Yes, I now have 6 sets.
2 S8 in series,
3 X S16 in parallel with the same kind of Jikong BMS that I started with 18 months ago that failed in 3 days. FIY, all Jikong BMS of that batch failed within 14 days.
Not just my setup.

If BMS where thrust worthy, making single strands can be a better idea.

Sadly, my experience is: they aren't
And I claim that with 3 I have enough knowledge to see that what China offers is crap, and I better build my "own" (DIYBMS)

One of the benefits of parallel, you balance out the cells.
Their internal resistance should be matched.

What if it isn't?
You received a bad batch, not just a seller who does "wrong" but mishap at development.

If I had millions, I just throw them away and buy new.
Probably also let the 8km electric line be build.
Being grit tied does have its advantages, even it it's unstable like Thailand.

I don't have this kind of money, and with it not the urge to throwing away 48* 152Ah cells.

With cell resistance difference, placing them in parallel you can even out the differences, making the total internal resistance of 3 the same in the whole pack.
 
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