200 Amp FLP Pouch cells?

[tecnodave]

      I have obtained a Fution Powerwall which contains 16 ea. 200 amp hour LFP Pouch cells, a BMS , and a all in one combo inverter/charger/solar charger of unknown make. Rated 5kva continuous 10 KVA intermittent duty , battery 51.2 volt 200 a.h.

The unit came to me damaged by dropping and electrical damage from a failed installation. It is 230 volt in and out but was installed in a 120/240 volt split phase system with a 10 kw. Grid tie system. It burned out a sump pump,referigerator,computer, etc.

My system is 24 volt with MidNite C150 controllers, Xeltech and Magnasine inverters so I only want to salvage the cells and set up for 24 volts.

I’ve seen pouch cells before but certainly not on this scale. There are 4 cells in each stack and one thought is to use as 2 separate banks with separate bms’s, this would avoid breaking up the stacks, the other thought would involve a complete tear down of the battery cells and rearranging each stack as 2P2S with all 4 stacks in series for a 2P8S setup with one BMS........

I’ve heard of maintaining constant pressure on pouch cells but these battery stacks have good clamping around the edges but not in the center , I’ve thought of fitting aluminum plates on the outside of these stacks.

Any thoughts on this would be greatly appreciated

[tecnodave]

More pic,s

[tecnodave]

And more pic,s

[tecnodave]

2 battery stacks of 4

[Steve_S]

Try # 2.

OK, I have not seen 200AH Pouch Cells, they would be too large IMO.  You have 4x50AH set in "parallel bundles" of 4 which are in compression frames.  DO NOT Undo the Frames, the pouches will expand if you do.  IF you must, then be certain the cells are in Lo Volt state, around 3.00V per cell to minimize the potential.  Don't take them below 2.75vpc.  Work quickly if reconfiguring the cells by splitting open the parallel sets.

The other electronics in the battery system is MOOT as you indicated this is EU 220-230V @ 50Hz Single Phase and cooked. Do NOTE something, the lighter gauge wire which you indicated is more than likely hi-capacity silicone jacketed wire.

Ideally, if you keep the Parallel Sets together, each "set" is viewed as "one cell" by a BMS, so you will require 8 Sets to make up a 24V Pack.  That's 32 Pouch Cells per 24V Pack providing 24V/200AH/5.12 kWh per pack.

Because we do not have the Cell-Specific Datasheets, we should assume ESS Grade Cells with a Max of 1.0C Discharge & 0.5C Charge C-Rates.  That then allows for a Max on 200A Discharge and 100A Max Charge Rate*.
*-Charge Rate:  Best to NOT exceed 80%, is a general unwritten rule.

You will require TWO 8S BMS' for LIFEPO Chemistry capable of handling 200A Discharge & 100A Charge.  One 200A Fuse per Battery Pack.  (I personally really like the BlueSea MRBF fuses (made by Bussman)).

* FET Based BMS' are available which can handle up to 300A (This is recent availability) BUT we always recommend oversizing FET BMS' to allow a safe margin.  Their ratings are essentially to the "edge" of their capability.  Some have Balancing Capabilities, mostly Passive (not suitable for large capacity cells) but now a few are coming out with Active Balancing as well.  FET Based BMS' do not use Relays or Contactors to connect/disconnect power.

BMS' which use Relays/Contactors are only limited for Amp handling by the Relay/Contactor capacity.  Relays do use power to operate which increases overhead.  Solid State Contactors on the other hand only use a few millivots to operate.  ALL Heavy Amp systems like EV's use Relays and/or Contactors pending on application.

Relays & Contactors can be a LONG discussion.  I've used & tested with TE/Kilovac's, Gigavacs Energy Saver & Non-Saver and assorted SolidState Relays and even had 500A & 1000A SSR's made for the testing cycles we did with the Chargery BMS back in the day.   (BTW, yes, I am the the same Steve_S who wrote the last series in Chargery BMS Manuals).  All of that testing & work actually led to the creation of Chargery's DCC Smart Solid State Contactor system which was a Huge Win for system users.

A WORD ON BMS' !
I have YET to encounter a "Perfect BMS" !  They all have quirks & foibles, moreso when they support multiple chemistries.  Understand that an EV for example is very specific and the BMS is specifically designed for THAT one single use, that's great & will do exactly what it is supposed to.  The "Generic" BMS' available to Battery Builders are generic for many use cases and therefore not quite up to that spec.  Even REC & Orion have their quirks & foibles too.  This means we have to live with some compromises, most of which can be simply classified as "nuisances".

Personally, I use the Chargery BMS8T because it is Contactor Controlling (I do not trust to FETS), the configurability / flexibility.  Jason @ Chargery has added the Low Cold Temp controls and other software mods we have asked for and developed the DCC with our input.  They are now completing the New P Series with advanced communications & features including Active Balancing for the larger cells.  They are working on the software now and sadly chip supply issues also affected them too. 

I RESIST Recommending a BMS because it is a personal thing and people are quirky.  Some want things that others don't and then there are the subjective issues and TBH, I got dumped on more than enough for recommending something that someone found "not quite" to their taste.

OverKill BMS = JK BMS out of China.  Reasonably GOOD FET Based BMS system, several options.
HelTec BMS = Well Known big maker.  Mostly FET Based BMS, they have some with Passive or Active Balancing and they also make standalone Active Balancers
TinyBMS = Well Known Hi Quality BMS more $ but very flecxible.
REC BMS, = More Pro Grade, Very Good Getting up in bucks.
Orion BMS = Pro Grade (EV capable too) Quite pricey .

Active Balancers:
I myself use QNBBM-8S which is now owned by DeliGreen in China (A large AliExpress/Baba Vendor) they work quite well   There are Many Brands out there and sadly over 1/2 are Shlock !  Heltec, QNBBM and KNOWN GOOD the rest I'd be weary of unless you get Good Reliable Credible reviews from actual users.

Paralleling LFP Packs.
This works amazingly well IF done right.  The packs will share Load & Charge fairly evenly and will balance each other out as well and overall operate in low stress mode as a result.  Pushing out 20A is easier than 40A right.  KISS Applied, my system as an example.   I use only Royal Excelene 4/0 Wire with Tinned SelTerm Lugs and my system is built for 300A delivery. 
- Each wire pair from Battery Pack to Common DC Bus is exactly the same length, same lugs etc.
- Each Shunt (Neg Line) per Pack is identically located.
- BATT Cables are kept together (reduces EFI/RFI)
- 4/0 Wires from DC Common Bus to 250A E-Panel through to Inverter.

Casing / Rack / Box.
You will want to have your packs in some kind of casing or box.  Never leave cells and their connection exposed, that is an Invitation to our Calamitous Enemy Mr Murphy and his damned Laws.  You want to ensure the packs are safe & secure, with no rodent/insection incursion possible.  You do not want any exposed contacts, you already know how fast an oopsie terminal crossing can go bad and go Boom.

CHARGING Systems:
I am not familiar with your iCharger system but I know many people use them.
Technically, each "individual" cell will not take more than 25A charge directly because they are 50AH cells.  In the "parallel set of 4" that reaches the allowable 100A 0.5C Rate for Charging.  That is the guide there.   
Top Charging & Top Balancing cells is NOT the same as Charging a full Battery Pack.
I've just updated to 1190AH from 910AH of LFP Capacity.  I use my Classic-200 which happily pushes 78A at the bank without a flinch and on a sunny day, I am in float by noon.  In Winter (Dec./Jan) when the sun is short, I use my Genset to charge via my Samlex EVO4024 which I've set to charge at 80A while providing Passthrough AC.  8 Hours genset time = 3 days of stored energy + what was used during the charge cycle.

I do use a Bench Charger a TekPower TP1540E which I use to Top Charge & Top Balance fresh LFP cells prior to assembly into full packs. 

For a view of my system & setup look here (not updated to most recent config yet):
https://diysolarforum.com/threads/my-diy-off-grid-cabin-setup-in-ontario-canada-24vdc-120vac.1484/

Hope it helps, Good Luck.
Steve_S

[tecnodave]

Steve-S

Thanks so much for the response, I’ve been reading your posts for some time now.  I do respect your knowledge there. I do realize that I have some kind of weird cells here. There are only 16 cells in this 48 volt system, there are 4 cells stacked in each frame, all the cell terminals are on one end of each stack. There is no way 48 cells in there, look at the pictures there. I’ve posted here, at diy, and at NAWS. No one has correctly identified these yet. I’ve got a new one on everyone here. The voltages are all correct for LiFePO4 at 3.2 volts/cell.

The manufacturer states that it is LFP, with 32 cells, I will put that down to rev. A vs rev B .  The picture on Amazon shows a slightly different system as front panel is a bit different .  The front cover is changed to be screwed in from the front, not from the sides like the one that I have. The front cover seems to be “bulged out a bit” to accommodate the 32 ea. 100 a.h. Cells in the current version.


This unit is new out of the box. It was bought online from Amazon. If failed to do what the homeowner warned it to do, that is backup his 120/240 volt power system. Obviously being 230 volts it does not have a neutral tap so the household system was in series/parallel with no neutral connection.

I was hired to find out why the unit burned out the appliances in the house. It took me all of several minutes to read the labels clearly stating that this unit is 230 volts AC in, 230 volts AC out. Of course it will not work in a “Split Phase” system as their is no neutral. The unit has no operational time on it at all. When I explained the ramifications of using this device in his million dollar hilltop home due to it not being UL listed and therefore “not code” and therefore his homeowners insurance is not valid....automatic out for the insurance company.....it’s right in there in your policy, it must be “UL Listed” and “Code Approved”  (it wasn’t)  The homeowner had me remove it from his home. I exchanged my time for the unit, I have only two hours in diagnosis of the system, not bad for 10 kWh LFP battery.


Please note that I’m no newbie to electronics, I’m a federally licensed Communications  Engineer. I installed solar power backup for our communications networks for General Electric Corporation in 1966-1967......YES THE 1960’s...
long before Solar was used in households.....long before “grid tie”.....to be sure our systems were very crude in comparison to what is done today. We were the pioneers in this. General Electric was the “prime contractor” for Atlantic Richfield Oli (ARCO) GE supplied all their communications networks , as such we had very early prototypes of the M-50 solar panels built by ARCO Solar.  We used many small scale solar systems to provide power to our mountain top radio repeater sites. I’ve long since retired from large corporations and continue to do electricity today.

FYI......Solar was invented by the Communications Industry , it was Bell Labs, the research arm of American Telephone and Telegraph who patented the “monocrystalline cell” in 1955 to power their communications networks.
They had operational solar systems powering mountain top radio microwave repeaters used in the communications networks by 1958

It Wes the communications industry both terrestrial and space that made solar affordable for the consumers, before that they were strictly industrial, far too expensive for consumers.

I only did solar professionally as a communications engineer, I’ve never done a residential grid tie or otherwise, only diy off grid systems. I work as a systems debugger, making existing systems work as they should. Systems Failure Analysis is my strong suite., and to that end, I continue to work in failure analysis, making all kinds of electrical/electronic systems work....I did a stint in computers as well......for the manufacturers.....on pre-production failure analysis......

I will set this system up and load test it, I do have POCO power in my workshop, it’s not at my residence where I do not have grid power. I do not have a decent 230 volt load but I’m sure I can cobble up something maybe two electric heaters in series?

In any case I respectfully disagree with you that this unit is 50 amp pouch cells with 4 cells parallel as one cell, look at the pictures again very closely, you will see only 4 cells in each stack, all wired in series, only 4 stacks of 4 cells each.

It is REALLY STRANGE that no one has seen anything like this, I’ve posted on 4 forums so far, many guesses but no one has said they have seen anything like this.

If I am wrong I will post it, I learn by doing and I eat my mistakes, that is how we move forward.

Thanks for responding

Tecno

[tecnodave]

Residue from my stint as a communications engineer, These ARCO M-50 solar panels were installed by me on a mountaintop in Southern California in 1965-1966-1967, Don’t remember the exact date but the time frame is correct.
Most of the array was destroyed by falling ice from the antenna towers, I contracted to GE and replaced this system with something else, too long ago to remember.

These are very rare 33 cell “self-regulating panels” designed for direct  connection to the battery with no controller....

50 plus years old AND THEY STILL WORK!

[tecnodave]

A few more pic’s of the “allegedly” 200 amp pouch cells showing their size....NOTE  all the pictures I have seen 50 amp pouch cells are about 5” X 7”.  By hands are large to xtre large, I can’t cover 1 cell with my XL hands, these are not 50 a.h. Cells


If I’m wrong I will post it here and diy and NAWS.......I have been wrong in the past I have no dought that I will be wrong again but I eat crow when I’m wrong.....just still trying to learn something new.

[tecnodave]

Couple more pics of the connections.  Left stack, #1 negative end.    Right Stack  #4, most positive end of stack,  the two in the background ate stacks 2 and 3 in the series setup.

[Steve_S]

A bit short on time for lengthy response...  I have machinery costing me pesos in rental sitting.... so... Excavators etc.
Me is a Geezer.  I start started my Electronics Life doing bord level work fore Control Data Corporation (Mainframes) then to IBM for a stint.  After that I went deep into Network Systems and involved with the International Protocol Standards & Communications Group.  YES I am a former PSC Eng that many cursed in the day...   Now retired and happily NOT thinking about that stuff anymore.