EVE-280 cells should these be clamped tight or spaced for expansion?

[justgary]

How does what you are suggesting explain how some cells/brands/batches don't bloat or expand during charge and discharge cycles while some others have issues with bloating even just while being stored?

The chemistry used by each manufacturer is very likely a trade secret and different for each one. Various amounts of additives to the electrolyte address various issues within the cell. I have never taken one apart, but it wouldn't surprise me to see differences as soon as you take the cap off. Are some brands more structurally sound? Maybe. Do they use foam inside to address bloating? Maybe. I don't know the differences.

The question about EVE cells and using compression is seemingly addressed by their data sheet and lifespan estimates. I plan to compress my EVE cells when I get them, then wire them for top balance, then rewire them for series use. This will be 16S2P plus a separate 4S battery (for another use)

 

[Itohmamma]

I have seen the video from Andy.

He is forgetting one main thing, that the cells are supposed to have a snug fit.
To prevent bulging, the walls of the cells simply are too weak to prevent this on their own in the long run.

2000-4000 cycles..
With charging during daytime and using 50-70% at night...
They can last ages.
Maximum life expectancy under most optimal conditions is 20 years.
They aren't Edison batteries!!

How stupid would you feel to ignore the guidelines given by the producers, who do that "extra mile" themselves when constructing their own packs?

You really believe Andy has more knowledge then the engineers over at BYD or EVE??

The whole spring "hoax" is over the top. "Too much of a good thing".
It won't hurt, also won't increase compared to a snug fit.

Can anyone produce a picture or video of 280ah cells that aren't snug / clamped after 2-3 years of continuous use?
And the same type with a snug fit?

Without it ..
We need to choose:
Follow Andy's logic, or the factory engineering team.

Up to you

Proper liquid foam pads for cell spacers does the trick! Keeping compression during cycling between 8psi and 17psi.

 

[Itohmamma]

The chemistry used by each manufacturer is very likely a trade secret and different for each one. Various amounts of additives to the electrolyte address various issues within the cell. I have never taken one apart, but it wouldn't surprise me to see differences as soon as you take the cap off. Are some brands more structurally sound? Maybe. Do they use foam inside to address bloating? Maybe. I don't know the differences.

The question about EVE cells and using compression is seemingly addressed by their data sheet and lifespan estimates. I plan to compress my EVE cells when I get them, then wire them for top balance, then rewire them for series use. This will be 16S2P plus a separate 4S battery (for another use)

Be sure to use long lasting liquid silicone foam between them before compressing.

 

[Capt Bill]

They're constructed differently which is obvious when you handle them. Whether it's the case or the way the layers are rolled or the materials used inside, who knows... There's also no liquid sloshing in the Lishen's. Like I said, it feels quite different.

IMO: That is really interesting information. ... I have the EVE 280 Ahs (16 cells online) . On my first set of 8, ... I did not notice the slightly wavy rectangular sides ... thinking space between each cell was best for cooling; I used double sided tape between each cell. I was surprised later when I re-organized my battery bank and pushed the cells together, and saw some light here and there, between "slightly" bulging sides pushed together.

I prefer to see perfectly flat planes on the side of my LiFePO4 cells. I learned on forum threads here, this was not unusual for EVE LiFePO4s. I AM Not sure, but I think there might be real A-Quality EVE cells that do have flat planes on their sides, but do not know; and my 1st set of cells was represented as A-Quality in (my memory of pre-purchase chat) by Xuba (4.2020) ... I currently have critical thoughts about compressing EVE Cells with the supplied solid bus bars too !!! ... to be fair, happy enough w $ to what I got ratio, to get started with LiFePO4 Battery options.

So your Lishen 272 Ah LiFePO4 Cells come with perfectly flat sided cells? and do not have recommendation to compress their cell for more life expected cycles ... in their data sheets? What can you say about that ? If so, Maybe the Lishen LiFePO4s would be a better choice over EVE LiFePO4s. Ya got my curious side perked to research along these lines.

 

[cinergi]

So your Lishen 272 Ah LiFePO4 Cells come with perfectly flat sided cells? and do not have recommendation to compress their cell for more life expected cycles ... in their data sheets? What can you say about that ? If so, Maybe the Lishen LiFePO4s would be a better choice over EVE LiFePO4s. Ya got my curious side perked to research along these lines.

Yes perfectly flat and nothing in their data sheets about compression. When you handle the cells they feel a lot more solid. You can't "squish" the cells with your hands like you can the EVEs. It's a little difficult to describe.. it feels more like a solid brick.

 

[Itohmamma]

Yes perfectly flat and nothing in their data sheets about compression. When you handle the cells they feel a lot more solid. You can't "squish" the cells with your hands like you can the EVEs. It's a little difficult to describe.. it feels more like a solid brick.

Either way, allowing expansion by limiting within specifications seems to be preferable to longevity.

 

[Capt Bill]

Yes perfectly flat and nothing in their data sheets about compression. When you handle the cells they feel a lot more solid. You can't "squish" the cells with your hands like you can the EVEs. It's a little difficult to describe.. it feels more like a solid brick.

Sounds like Lishen 272 Ah LiFePO4 might be a Better Cell to me. I wish I did not have to consider compressing my EVE cells for potentially more life cycles while getting just solid bus bars from the suppliers with them, and slightly wavy sides I did not anticipate. I still wonder if A Grade EVE Cells have flat sides or NOT ??? ... I have not been able to squish a EVE Cell with my hands (just tried on off line worst cell w has slight bulge on both sides), and see no signs of liquid sloshing around inside.

Wondering: ... Did you Amp/hr test your 272 Ah cells. How did that go? I am now curious to research about Lishen and whatever other cells have flat side panels.

... Will Add: While am expressing my Critic View related to the EVE cells I obtained from China, I still think I got a good value for the price I paid, especially when I look at the prices of fully built out LiFePO4 Batteries available online, and in warehouses near where I live in Northern California. .... Super Glad to See Will Prowse highlighting some of the recent better best deals in pre-built server rack batteries warranties coming to the market place etc on his youtube lessons channel (on a roll ... Will :+)

 

[cinergi]

Sounds like Lishen 272 Ah LiFePO4 might be a Better Cell to me. I wish I did not have to consider compressing my EVE cells for potentially more life cycles while getting just solid bus bars from the suppliers with them, and slightly wavy sides I did not anticipate. I still wonder if A Grade EVE Cells have flat sides or NOT ??? ... I have not been able to squish a EVE Cell with my hands (just tried on off line worst cell w has slight bulge on both sides) . ... Did you Amp/hr test your 272 Ah cells. How did that go? I am now curious to research about Lishen and whatever other cells have flat side panels.

My EVE 280's were 268 - 281 Ah (most of them below 280). My Lishen 272s were, get this, 286-288.
As far as squishing.. I don't know that you could see it's squishy .. for me, it just feels different when I apply pressure to it vs. a Lishen which feels more like a solid brick.
Unfortunately the Lishen terminal height is different than the EVE so a solid bus bar between an Lishen and an EVE would not work without compensating for the height first. My 4 Lishen's are actually collecting dust right now.

 

[Itohmamma]

Sounds like Lishen 272 Ah LiFePO4 might be a Better Cell to me. I wish I did not have to consider compressing my EVE cells for potentially more life cycles while getting just solid bus bars from the suppliers with them, and slightly wavy sides I did not anticipate. I still wonder if A Grade EVE Cells have flat sides or NOT ??? ... I have not been able to squish a EVE Cell with my hands (just tried on off line worst cell w has slight bulge on both sides) . ... Did you Amp/hr test your 272 Ah cells. How did that go? I am now curious to research about Lishen and whatever other cells have flat side panels.

My EVE304 are perfectly flat and I’m padding with 4.5mm liquid silicone foam pads which are intended to stay within the recommended compression at all SOC. Also If you search copper amps carrying capacity, I concluded their factory, or expensive special order flex, busbars are inadequate. I’m choosing to make my own from 2/0 flexible copper wire, with appropriate copper terminals (I’m going one step further as I’ve purchased bare copper which I will silver plate myself). This would increase conductivity while reducing resistance.

 

[Capt Bill]

My EVE304 are perfectly flat and I’m padding with 4.5mm liquid silicone foam pads which are intended to stay within the recommended compression at all SOC. Also If you search copper amps carrying capacity, I concluded their factory, or expensive special order flex, busbars are inadequate. I’m choosing to make my own from 2/0 flexible copper wire, with appropriate copper terminals (I’m going one step further as I’ve purchased bare copper which I will silver plate myself). This would increase conductivity while reducing resistance.

Wonder which supplier your EVE304 came from. I wish my Eve Cells were perfectly flat sided.

... Re Flexible BusBars ... I saw the Flexible 75mm2 braided on Alibaba rated at 400 (Chinese) Amps on AlibabaExpress, and lesser 50mm2 rated at 200 amps. ... While my 280Ah LifePO4s might only see 140 amp max currents, it would be nice to see braided bus bars w an amp rating that matched my 300 amp Fuse Blocks to Each of my 24v 280Ah LiFePO4 Battery Banks. ... Have thought of doubling up on the 50mms Braid Bus Bars that come up as an option on DocanPower's website (with 32 minimum/ and need to talk story on bigger order) ... to get better amperage ability if I ever go to compression of my cells.

 

[Itohmamma]

EVE provide 2mm thickness by 20mm for 300ah batteries. I do not believe everything that a Chinese manufacturer tells me, for instance 2000 lm flashlight? Some of them are actually not as bright as a 500 lumes.
Check it out for yourself, https://www.electrical4u.net/calculator/busbar-current-calculator-online/

 

[Frank in Thailand]

Busbars are a strange thing.
Or better, copper is strange metal
Yes, it heats up with high amperage.
Bit it resistance gets lower when warmer.
So while it might get warm fast, it can handle a LOT of ampere before it becomes hot.

Then the next "problem" the aluminium terminal is really good heat conductor.
It cools the busbars...

The lifepo4 cell, about 6kg (300Ah) is a lot of mass to heat up.

And let's be realistic guys (and girls) are you ever going to load 300A?
On a solar system?

If powerful enough to go above 100-150A you should already step up for voltage.
Say you have S16, 51.2v LiFePO4
300A that's 15000 watt push or draw to get 300A.

At a peak? Sure... It might happen.
My setup theoretical can..
(4x260Ah, 1040Ah, still just 75A per set)

And even I won't draw 300A for a long time.
15.000 watt is a LOT of electricity.
Most (S16, 551.2v) setups never pass the 75A, and even that not hours.

Will did a test with the "thin" busbars and did draw "crazy high" amperage, both the (Daly smart) BMS and the busbars didn't get warm.

We can theorise all we want
That's real life.
All the charts doesn't tell you how it works with just 10-15 cm of busbar, Cable ratings are per meter....
Distance does matter.
I can't recall seeing any length indication at the busbars charts.

 

[Frank in Thailand]

@Itohmamma ,
I'm happy for you that you found a use for your liquid silicone pads.
Spacing cells 4.5mm by something semi solid isn't going to do much good.

Not for temperature, not for compression.

What works for you, work for you in your situation.
There isn't a LiFePO4 manufacturer that uses 4.5mm thick gelpads between the cells.

There are more videos on YouTube how professional builders build
.
Laser welding, aluminium busbars and housing under compression.

That's how it is intended to be used.
Not drilling a hole in the terminal, tapping thread..... And so on.

Sure, you can use your angle grinder to make a mixer.

It's also electro motor, have on/off switch, same wattage...
Just don't expect it to be as good as a mixer build by a factory, as mixer from the start...

We are NEVER going to have the same quality and stability a "pre-build" laser welded LiFePO4 battery.

Just only that we have inferior contact with the terminals is already a start.


The 300A example one post earlier...

Drilling holes and tapping threads was something "we" could get away with when the capacity was 20-50ah.
No one was even thinking about giving it "full load" of 50A, mainly because the chemistry wasn't capable yet, also...
The contact... It could not handle that much amperage.


Then things evolved..
50 to 100, to 200 and even 300A.
C rating went up, even to 2..

Only a fool would think that what you could get away with at low capacity, 50A, works the same at 300 or 600A!

The terminal surface did not increase.
50Ah, 150, 280, same terminal size.

When used as we do (not think we want or mightike to do), solar installation.

Charge during daytime, 8-12 hours.
We don't like empty, so we charge probably less then 75%.
In 8-12 hours.

Use at night, 12-16 hours...
C rating of 0.2 we probably never reach.

We can theorise all we want about how the cells would react with "high temperature" due long loads of C1 or C2 (+250A)..
Realistic... We won't use.
If ever... A spike for a short time.

14.5kw solar in Thailand, +1000Ah LiFePO4 and 16.5kw inverter..
Max...
My usual consumption with 2 airconditioning units, 950w mining rig, 2000 watt 50m pump, 1100 watt Reverse osmosis several other pumps (350-500w)...
Even with all 5 airconditioning working, the main pumps starting, I don't come close to the 16.5kw.
Usually it stays (far) under 5000w.

And I'm energy hungry

Electrical cars... That's a whole different ballpark.
DIY Solar forum does not cover this.

 

[Itohmamma]

Busbars are a strange thing.
Or better, copper is strange metal
Yes, it heats up with high amperage.
Bit it resistance gets lower when warmer.
So while it might get warm fast, it can handle a LOT of ampere before it becomes hot.

Then the next "problem" the aluminium terminal is really good heat conductor.
It cools the busbars...

The lifepo4 cell, about 6kg (300Ah) is a lot of mass to heat up.

And let's be realistic guys (and girls) are you ever going to load 300A?
On a solar system?

If powerful enough to go above 100-150A you should already step up for voltage.
Say you have S16, 51.2v LiFePO4
300A that's 15000 watt push or draw to get 300A.

At a peak? Sure... It might happen.
My setup theoretical can..
(4x260Ah, 1040Ah, still just 75A per set)

And even I won't draw 300A for a long time.
15.000 watt is a LOT of electricity.
Most (S16, 551.2v) setups never pass the 75A, and even that not hours.

Will did a test with the "thin" busbars and did draw "crazy high" amperage, both the (Daly smart) BMS and the busbars didn't get warm.

We can theorise all we want
That's real life.
All the charts doesn't tell you how it works with just 10-15 cm of busbar, Cable ratings are per meter....
Distance does matter.
I can't recall seeing any length indication at the busbars charts.

Well for the sake of argument, let us say that you have 3500 amp hours at 48 V where you want to charge up a tesla on tier 3, and that’s going to run for an hour maybe more, and all the while he’s certainly like to continue to run all of your appliances, and your two air conditioners in your computer and your large screen TV etc. etc.. I’m planning for the worst case scenario and I realize that when bus bars heat up so do the batteries and the batteries heat up, degradation sets in.
Unless you can predict 15 years into the future? It’s for that particular reason that I am now upgrading my two 48v/250 amp hour 16s Daly to two 48v/300ah daly. As gasoline and natural gas prices increase… the need for renewable self producing electricity becomes more desirable, and maybe absolutely necessary.

 

[Itohmamma]

@Itohmamma ,
I'm happy for you that you found a use for your liquid silicone pads.
Spacing cells 4.5mm by something semi solid isn't going to do much good.

Not for temperature, not for compression.

What works for you, work for you in your situation.
There isn't a LiFePO4 manufacturer that uses 4.5mm thick gelpads between the cells.

There are more videos on YouTube how professional builders build
.
Laser welding, aluminium busbars and housing under compression.

That's how it is intended to be used.
Not drilling a hole in the terminal, tapping thread..... And so on.

Sure, you can use your angle grinder to make a mixer.

It's also electro motor, have on/off switch, same wattage...
Just don't expect it to be as good as a mixer build by a factory, as mixer from the start...

We are NEVER going to have the same quality and stability a "pre-build" laser welded LiFePO4 battery.

Just only that we have inferior contact with the terminals is already a start.


The 300A example one post earlier...

Drilling holes and tapping threads was something "we" could get away with when the capacity was 20-50ah.
No one was even thinking about giving it "full load" of 50A, mainly because the chemistry wasn't capable yet, also...
The contact... It could not handle that much amperage.


Then things evolved..
50 to 100, to 200 and even 300A.
C rating went up, even to 2..

Only a fool would think that what you could get away with at low capacity, 50A, works the same at 300 or 600A!

The terminal surface did not increase.
50Ah, 150, 280, same terminal size.

When used as we do (not think we want or mightike to do), solar installation.

Charge during daytime, 8-12 hours.
We don't like empty, so we charge probably less then 75%.
In 8-12 hours.

Use at night, 12-16 hours...
C rating of 0.2 we probably never reach.

We can theorise all we want about how the cells would react with "high temperature" due long loads of C1 or C2 (+250A)..
Realistic... We won't use.
If ever... A spike for a short time.

14.5kw solar in Thailand, +1000Ah LiFePO4 and 16.5kw inverter..
Max...
My usual consumption with 2 airconditioning units, 950w mining rig, 2000 watt 50m pump, 1100 watt Reverse osmosis several other pumps (350-500w)...
Even with all 5 airconditioning working, the main pumps starting, I don't come close to the 16.5kw.
Usually it stays (far) under 5000w.

And I'm energy hungry

Electrical cars... That's a whole different ballpark.
DIY Solar forum does not cover this.

Well I hope I can use them!! As they are special order from a solar liquid neoprene foam manufacturer in China, Who Assured me their compression force will continue to perform under extreme temperature range and long after the life of my EVE304 battery packs. Check with me in 15 years and I will provide you my results.

 

[Frank in Thailand]

For the sake of your argument..
3500ah..
That is 11.5 X 300Ah. Cell sets of 16 cells with 300Ah.

Tier 3 is only 11kw.
My current setup with 16.5kw would be able to handle this, with 1000ah battery.
1000 X 51.2 = 51kw.
16.5kw is just C 0.25 or discharge the +1000ah battery at 75A.

So your worse case scenario is 75 A on the 300Ah pack...
If you would have 3.5..

You have 3500ah..
So you have 7.5A load during your worse case scenario.

Edit:
Unless you are planning to charge the Tesla 50kwh battery (for model 3) with your home built 300ahx51.2v = 15kwh at maximal capacity....

Again... This is solar forum for normal home usage.
Draining the cells as fast as possible to recharge your EV...
Isn't normal home usage

 

[Itohmamma]

Well for the sake of argument, let us say that you have 3500 amp hours at 48 V where you want to charge up a tesla on tier 3, and that’s going to run for an hour maybe more, and all the while he’s certainly like to continue to run all of your appliances, and your two air conditioners in your computer and your large screen TV etc. etc.. I’m planning for the worst case scenario and I realize that when bus bars heat up so do the batteries and the batteries heat up, degradation sets in.
Unless you can predict 15 years into the future? It’s for that particular reason that I am now upgrading my two 48v/250 amp hour 16s Daly to two 48v/300ah daly. As gasoline and natural gas prices increase… the need for renewable self producing electricity becomes more desirable, and maybe absolutely necessary.

Oh yeah by the way, putting the pads between each separate the cells will make the compression quite easy to calculate. Squeeze the 50% SOC pack to approximately 3.2mm , plus or minus. This provides approx 7psi evenly between the cells. Now wherever the weakest point (generally center of the cell) will bulge (up to 1mm when 100% SOC) these silicone neoprene will allow resistance to not exceed 17 psi, yeah let’s point out what batteries can sustain internal damage.

 

[Itohmamma]

@Itohmamma ,
I'm happy for you that you found a use for your liquid silicone pads.
Spacing cells 4.5mm by something semi solid isn't going to do much good.

Not for temperature, not for compression.

What works for you, work for you in your situation.
There isn't a LiFePO4 manufacturer that uses 4.5mm thick gelpads between the cells.

There are more videos on YouTube how professional builders build
.
Laser welding, aluminium busbars and housing under compression.

That's how it is intended to be used.
Not drilling a hole in the terminal, tapping thread..... And so on.

Sure, you can use your angle grinder to make a mixer.

It's also electro motor, have on/off switch, same wattage...
Just don't expect it to be as good as a mixer build by a factory, as mixer from the start...

We are NEVER going to have the same quality and stability a "pre-build" laser welded LiFePO4 battery.

Just only that we have inferior contact with the terminals is already a start.


The 300A example one post earlier...

Drilling holes and tapping threads was something "we" could get away with when the capacity was 20-50ah.
No one was even thinking about giving it "full load" of 50A, mainly because the chemistry wasn't capable yet, also...
The contact... It could not handle that much amperage.


Then things evolved..
50 to 100, to 200 and even 300A.
C rating went up, even to 2..

Only a fool would think that what you could get away with at low capacity, 50A, works the same at 300 or 600A!

The terminal surface did not increase.
50Ah, 150, 280, same terminal size.

When used as we do (not think we want or mightike to do), solar installation.

Charge during daytime, 8-12 hours.
We don't like empty, so we charge probably less then 75%.
In 8-12 hours.

Use at night, 12-16 hours...
C rating of 0.2 we probably never reach.

We can theorise all we want about how the cells would react with "high temperature" due long loads of C1 or C2 (+250A)..
Realistic... We won't use.
If ever... A spike for a short time.

14.5kw solar in Thailand, +1000Ah LiFePO4 and 16.5kw inverter..
Max...
My usual consumption with 2 airconditioning units, 950w mining rig, 2000 watt 50m pump, 1100 watt Reverse osmosis several other pumps (350-500w)...
Even with all 5 airconditioning working, the main pumps starting, I don't come close to the 16.5kw.
Usually it stays (far) under 5000w.

And I'm energy hungry

Electrical cars... That's a whole different ballpark.
DIY Solar forum does not cover this.

DYISOLAR on YouTube does cover EV charge. I’m paying $6/gal gasoline… might be $10 very soon, and for the Foreseeable future. I would rather have more than I need than need more than I have. Besides, larger busbars have less resistance, therefore less heat.

 

[Frank in Thailand]

yeah let’s point out what batteries can sustain internal damage.

That's an easy one.
Not any battery can sustain internal damage

I'm happy for you that you are in the position to educate BYD, EVE, Lishen, CALB on how they need to produce their batteries for EV's.
Please post your scientific study papers, how they are doing it wrong all those years.
Wrong is a too strong word, "have room for significant improvement" is better suited.

I don't hold all the knowledge. You might be right.

Cost efficiency is an important factor for many companies.
It might improve over the "normal" method, increase a few cycle.
usually the busses and trucks get new packs after 3000-3500 cycles.
2% increase in cost should give 10% more cycles. (for factory products)
in 15 years, my inverters probably will have been replaced, and i have slowly build enough "Edison batteries".
They last over 60 years.
with a daily cycle, theirself discharge isn't that important.
I have enough space for huge batteries, and enough space to add a few more solar panels to compensate for the lesser efficiency of the Edison.
@ $110 for 345w, when the nickel price drop again, (5 years?) time enough to start building them (or perhaps buy)

I expect my lifepo4 to last 10 years, before I need to make adjustments to our energy consumption,
up to 15 before they don't provide enough.
my solar panels 20 years, I hope 30, or longer...
the mining rig won't last 10 years perhaps 1 or 2 years.... then 950 watt extra space (roughly 12.5 kw battery)

Before building, I did like most, make many calculations, theorising on what is best, and can it be improved.
yes, cooling solar panel with water will improve output. not practical.
yes, mirrors will increase solar output, but the heat shorten it lifespan..
combination would be amazing...
or just buy 10% more panels, and have stable, maintenance free solution.

Same goes for the battery......
You can try to outsmart the professionals, and might succeed for your setup.
following the "known path" will most likely provide you with a longer term working stable solution.
end of the line provide more cheaper solution, as we do not need to reinvent the wheel.

Reinventing is a whole lot more fun
usually does cost more and doesn't reach the same quality, absolutely more fun

 

[Frank in Thailand]

DYISOLAR on YouTube does cover EV charge. I’m paying $6/gal gasoline… might be $10 very soon, and for the Foreseeable future. I would rather have more than I need than need more than I have. Besides, larger busbars have less resistance, therefore less heat.

Thailand 40 thb per liter € 1.10
europe price as high as € 3 per liter.
3.785.. so € 11.355 or $12.- per gallon in Europe...
those prices are already there.

good thing tesla's are cheap
petrol car €20.000, Tesla €50.000
€ 30.000 difference, : 11.35 = 2650 gallon
petrol car average 25.4 miles per gallon, roughly 105k miles
average 13.500 miles per year (usa)
roughly 8 years worth of petrol costs.
you need to loan 30.000 more at 6.5%
or have 30.000 less to invest with average 10% return..

yes, in +10 years you have reached the ROI (average numbers)

While that isn't that much different from Solar, that one will last +25 years.
i doubt the tesla will last 25 years.
would be great if it did.

I absolutely would like to drive EV or Hybrid
That i have china inverter and EVE cells already shows that my budget isn't capable of buying it.
we drive china pickup on LPG $1.47 per gallon, and can drive way over the 25.4 miles..

Living off grid, where cable to hour home would costs about $50.000 ...
solar is the best way to go.

not due the price of electricity. that's a nice bolus we don't need to pay for that.
only 11 kw.... (tier3) isn't that special. my setup can handle at this moment.
I do have over 11 kw solar production, charging one battery from the other via inverter is kinda inefficient...

my 5.5kw inverter have max 5.5 MPPT.
I have higher voltage setup (+350v) 2 of the 3 inverters are mostly used as MPPT.
they can be used... and a victron solar charge controller is the same price as my 5.5 kw unit.
yes, probably will last longer...
in 10 years, i will see what the development have brought.
perhaps lower EV prices.

 

[Itohmamma]

That's an easy one.
Not any battery can sustain internal damage

I'm happy for you that you are in the position to educate BYD, EVE, Lishen, CALB on how they need to produce their batteries for EV's.
Please post your scientific study papers, how they are doing it wrong all those years.
Wrong is a too strong word, "have room for significant improvement" is better suited.

I don't hold all the knowledge. You might be right.

Cost efficiency is an important factor for many companies.
It might improve over the "normal" method, increase a few cycle.
usually the busses and trucks get new packs after 3000-3500 cycles.
2% increase in cost should give 10% more cycles. (for factory products)
in 15 years, my inverters probably will have been replaced, and i have slowly build enough "Edison batteries".
They last over 60 years.
with a daily cycle, theirself discharge isn't that important.
I have enough space for huge batteries, and enough space to add a few more solar panels to compensate for the lesser efficiency of the Edison.
@ $110 for 345w, when the nickel price drop again, (5 years?) time enough to start building them (or perhaps buy)

I expect my lifepo4 to last 10 years, before I need to make adjustments to our energy consumption,
up to 15 before they don't provide enough.
my solar panels 20 years, I hope 30, or longer...
the mining rig won't last 10 years perhaps 1 or 2 years.... then 950 watt extra space (roughly 12.5 kw battery)

Before building, I did like most, make many calculations, theorising on what is best, and can it be improved.
yes, cooling solar panel with water will improve output. not practical.
yes, mirrors will increase solar output, but the heat shorten it lifespan..
combination would be amazing...
or just buy 10% more panels, and have stable, maintenance free solution.

Same goes for the battery......
You can try to outsmart the professionals, and might succeed for your setup.
following the "known path" will most likely provide you with a longer term working stable solution.
end of the line provide more cheaper solution, as we do not need to reinvent the wheel.

Reinventing is a whole lot more fun
usually does cost more and doesn't reach the same quality, absolutely more fun

Thank you for your support ?. I’m following manufacture data regarding prismatic cell compression increases cycle life. I’m following manufacture testing data on liquid silicone foam spacers. (Which will at minimum reduce heat transfer between cells and contact damage in my mobile application). So at the very least it will help and protect from vibration damage and heat dissipation. 32 LiFeP04 cells is a huge investment, and any thing that helps is worth the small effort.?‍

 

[Deleted member 9967]

Thank you for your support ?. I’m following manufacture data regarding prismatic cell compression increases cycle life. I’m following manufacture testing data on liquid silicone foam spacers. (Which will at minimum reduce heat transfer between cells and contact damage in my mobile application). So at the very least it will help and protect from vibration damage and heat dissipation. 32 LiFeP04 cells is a huge investment, and any thing that helps is worth the small effort.?‍

Ok please teach me.
What the heck are "liquid silicone foam spacers"?
They sound like something I could use as mine are on a moving vehicle.
Thanks you.

 

[Frank in Thailand]

Yes..
I know it's a huge investment.
I did 48x 152 at the price 280 is now, and few months later 32 X 280ah...

I tried to reinvent also..
And being "new" development (larger capacity being affordable) not much was known in DIY world (end 2019, begin 2020)
What a leap has been made in those 2 years

If the pre-build laser welded BYD cells where (affordable) available back then, I best could have bought those. (In Thailand $1250 for S16, 260 Ah) (2xS8)

I lost thousands of dollars due many smaller mistakes, what eventually ended in catastrophe...
Not really, the room was "fire proofed"..
House still there

Keep it as simple as possible, least points of failure and do follow the "known paths"...
That will provide the lost stable setup what will last the longest.

Aim for 10 years...
That is a really long time..
You remember your life 10 years ago? How different from now?
Probably in 10 years the same...

Here (hot Thailand) lead acid dies (unless Air-conditioning cooled) in 2-3 years. We have regular +40c (over 105F)
lead acid doesn't like that

For you, i read Mobile solution.
Unless it's off the road truck, it doesn't have much to suffer.

Your busbars are probably with a stud and a nut..
That is more sensitive to vibration.
Usually I would suggest loctite.
It does make maintenance almost impossible...
Nylon lock nuts?

Please do use loctite if the studs aren't laser welded in the terminals.

Do use quality di-electric grease (oxiguard) and a torque meter (!!!)
It will help so much with the maximum torque the thread (in the aluminium terminal) can handle.
With loctite Red (do use primer/activator as aluminium and stainless steel need it) you can do 4Nm, without on 3Nm I have had threads being pulled out...

While not so complicated to fix with the right tools and equipment, it's a lot of additional work.

You can directly tap the helicoil thread in the old M6, but will need to adjust the tap, as it should have a flat tip (not pointy)

Loctite Red works perfect.
So does several epoxies (the long 24h curing ones)

Most cells are hand drilled tapped by the Chinese seller..
It's not uncommon to have slightly diagonal studs instead of vertical...

The threads aren't optimal, and the cells aren't intended to be used this way.
It will work, you just need to be careful and use the correct tools.


A simple digital torque meter will set you back $35-40 and probably will safe you many additional hours of work.

 

[Itohmamma]

Ok please teach me.
What the heck are "liquid silicone foam spacers"?
They sound like something I could use as mine are on a moving vehicle.
Thanks you.

LIQUID SILICONE https://www.applerubber.com/hot-top...ou-need-to-know-about-liquid-silicone-rubber/

 

[Itohmamma]

LIQUID SILICONE https://www.applerubber.com/hot-top...ou-need-to-know-about-liquid-silicone-rubber/

I’m of the belief that the corners of a prismatic cell normally Keep their shape and any bulging comes from the large flat sides, the weakest point, which would probably be the center of the cell. By using a full spacer pad, any expansion will have A place of resistance. I chose not to use a solid substrate because during expansion it may cause excessive resistance pressure (I believe usually from the center of the cell) But from everything I’ve read any pressure greater than 17 psi and any part of the cell may cause internal problems.
The correct soft “goldilocks silicone” spacer should meet all compression requirements, and be relatively easy to incorporate in a cell pack. I stated earlier…..to obtain 8psi resistance force, starting approximately 40-50% SOC. I intend to compress them 25% of their thickness, thereby their resistance to expansion of @1mm (according to the liquid silicone foam pad manufacture) will be well within the range of 17 psi resistance.