Wolf's PowIRwall

ajw22

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Nov 16, 2018
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My powerwall batteries with ca 7000 cells of varying SoH have been in use for nearly 1.5 years, and they've definitely been degrading (losing capacity) at different rates. Every month or two I bring the pack capacities back in balance by surgically replacing a couple of low capacity cells with higher capacity cells.
Will be very interesting to see if your packs made from carefully selected cells all degrade at the same pace, thus requiring no maintenance.
 

Wolf

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ajw22 said:
My powerwall batteries with ca 7000 cells of varying SoH have been in use for nearly 1.5 years, and they've definitely been degrading (losing capacity) at different rates. Every month or two I bring the pack capacities back in balance by surgically replacing a couple of low capacity cells with higher capacity cells.
Will be very interesting to see if your packs made from carefully selected cells all degrade at the same pace, thus requiring no maintenance.
It will be very interesting indeed!
Right now it is very encouraging to see the packs come so close to each other in Ah results.
I am charging the packs to 4.2V till the "Keep" indicator comes on on the iCharger, then regen discharge at 30A to 3.0V, then storage charge to 3.7V.

I am hoping my diligence will pay off.

Wolf
 

completelycharged

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I do think that the initial selection and patience will work out well. From your detailed testing and understanding of cells interactive behaviour in a pack the end result should be quite good and last longer than the typical build here.

"I'm kinda sticking my neck out as I am a huge proponent of IR and the importance of it indicating the health and longevity or a cell." +1
 

Wolf

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Update:

#1: Well I found another corroded cell that tested just fine had great IR, mAh and V and looked perfect from the outside.
I am now a complete believer in re-wrapping All cells.

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#2: The packs are coming together very well. I have 9 totally complete 2 packs re-wrapped and 3 more waiting for their final check and re-wrapping. I had to cannibalize the 15th pack for cells that after the final test of IR and V before the re-wrap I deemed to be just a little below my stringent specifications.
The 3 packs on the right are my regen packs and the icharger is doing a regen at 30A yea!!
Sorry the spider plant went wild. It got a trim this morning.

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Now to the problem. I initially bought 20 feet of the 5p cell level fuse sheet and well ran out. I need another 15 feet to complete my packs.
I have emailed and called Battery Hookup several times to see if they are expecting any new stock but no answer whatsoever.
I even sent Mike a PM whose signature has their advertisement for their cells for sale ( he is not an employee or part of their business) to see if they knew if any new supply would come in.
He did get in touch with them (I thank him dearly for that) and was told 3 to 4 weeks.
In the meantime I decided to take advantage of the sale of their Modem batteries and sent them an email requesting a price for 400 of the units. Got an email back saying yea we can do that for x price send us your zip code so we can give you a complete price with shipping. I did that and that is the last I ever heard from them again. Now the website says that they are out of stock. Hmm??
By the way Mike your signature is "Out of Stock" :p

Sorry to be so long winded but here is the question. If anyone has any 5p cell level fuse sheets available please let me know and I will purchase them.

Thanks for listening.

Wolf
 

Korishan

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Wolf said:
Update:

#1: Well I found another corroded cell that tested just fine had great IR, mAh and V and looked perfect from the outside.
I am now a complete believer in re-wrapping All cells.

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The big question is, where did the rust come from? If it's from another cell, container, iron in water, etc. then it's probably fine. If the rust came from micro pits in the nickel layer on the cell, the oxidation could potentially keep happening and digging deeper into the casing until the structural integrity is compromised.

Maybe after 'thorough" cleaning of the cell to get as much rust off as possible, to then coat the cell where the rust was in some kind of sealant, like clear fingernail polish or lacquer. That way oxidation can't continue to develop later on down the road. Even re-wrapping may not be enough protection alone.

Just my 2 * 10^-2 ;)
 

Wolf

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Korishan said:
The big question is, where did the rust come from?

Maybe after 'thorough" cleaning of the cell to get as much rust off as possible,............................
Who knows where it came from Soda, water,coffee spilled on the laptop? Battery left in the elements maybe took a bath?

Ah no that cell gets replaced with one of ~equal value never to see the potential of getting into my PW.
I got enough cells to avoid having to use those.
It will get a rewrap though to protect ME from it shorting out, go into the discharge unit, and go away to the recycler.
Bye Bye.

The point I was making is that even though the cell looked great on the outside once the wrapper came off there was this corrosion that could not be seen before. In your automotive vernacular it's like taking the plastic bumper cover off just to find that the actual steel bumper is just about rusted out. Oh wait you live in Florida that doesn't happen to cars there just in the northeast. :p

Wolf
 

100fuegos

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May 29, 2018
Messages
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Wolf said:
Production has begun on the packs.
All bus bars have been completed and 9 of these packshave been built.
Every one (720) have been rechecked for IR and V and re-wrapped.

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I must say I do like the Kweld a lot once you get it dialed in it gives consistent results.
Only 5 more to go and 1 spare.
Testing the Ah of the packs right now and will post results as soon as all of them have been tested.
Testing paramiters are:
Using Icharger x6 initial testing was done with a external resistor to allow 20A discharge. Once 3 packs where initially tested
those were hooked up in series to provide a charging and regenerative discharge holding tank capableof 30A either in or out.
Sneak peek at the results so far? OK

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Wolf

I am sure you noticed this. Didn't you?





image_rwwolm.jpg
 

Wolf

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100fuegos said:
I am sure you noticed this. Didn't you?


image_rwwolm.jpg
LOL yes I did! Good eye.

I spotted it when I posted it and left it in there just to see if anyone would notice.
You win the prize. :D
Wolf
 

Korishan

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Wolf said:
The point I was making is that even though the cell looked great on the outside once the wrapper came off there was this corrosion that could not be seen before. In your automotive vernacular it's like taking the plastic bumper cover off just to find that the actual steel bumper is just about rusted out. Oh wait you live in Florida that doesn't happen to cars there just in the northeast. :p

LOL you'd be surprised :p Though, not from salt. Usually from an excess build up of mucky dirt/mud keeping it constantly in a state of wet saturation. But, does take a lot longer than those up north.
 

Generic

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Joined
Oct 23, 2018
Messages
210
Korishan said:
Wolf said:
Update:

#1: Well I found another corroded cell that tested just fine had great IR, mAh and V and looked perfect from the outside.
I am now a complete believer in re-wrapping All cells.

image_rihbys.jpg

image_vlnjcp.jpg

The big question is, where did the rust come from? If it's from another cell, container, iron in water, etc. then it's probably fine. If the rust came from micro pits in the nickel layer on the cell, the oxidation could potentially keep happening and digging deeper into the casing until the structural integrity is compromised.

Maybe after 'thorough" cleaning of the cell to get as much rust off as possible, to then coat the cell where the rust was in some kind of sealant, like clear fingernail polish or lacquer. That way oxidation can't continue to develop later on down the road. Even re-wrapping may not be enough protection alone.

Just my 2 * 10^-2 ;)

If I'm hijacking this thread, feel free to orphan this post. Since you bring up rust, there's something I've always been wondering - If electrolyte is so caustic, why don't all cells rust from the inside out within a matter of time? is the nickel plate reallythick on the inside of the cell?
 

Wolf

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Generic said:
If I'm hijacking this thread, feel free to orphan this post. Since you bring up rust, there's something I've always been wondering - If electrolyte is so caustic, why don't all cells rust from the inside out within a matter of time? is the nickel plate reallythick on the inside of the cell?

Generic,
I think it is more about O2. Oxygen is an oxidizer and given the right circumstances will combine with anything to form another state of the material it combines with.
The cells are sealed so there is no new introduction of O2 so nothing to (oxidize). Also I believe Nickel is somewhat better at resisting corrosion than most metals other than gold.

That's what I'm thinking.

Wolf
 
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Korishan

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And platinum. But I doubt we'll see cells with Platinum in them :p
 

Wolf

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Update:
3 things
#1:
Batrium is on its way!!! Woohuu!!

image_xvzwwk.jpg

#2:
Pack number 12 all re-wrapped and ready for cell level fuses. (If Battery Hookup ever gets the cell level fuse sheets in) :(
I do have a backup plan as I have 20 feet of each 2p and 3p sheets. May not look as uniform as the other packs but it will work.
2 more to go :D
All cells are unwrapped without the use of a razor blade or utility knife as when you cut the insulation off with such devices you leave a score on the casing of the cell that will weaken the cell and give it a point of breakage. Just like when you score a sheet of glass it will break on that score. the same with a cell internal pressures will cause the score to be the weak spot. Keep that in mind when re-wrapping cells.
Here are the cells waiting for their new covers. I already did the red ones.

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Onto the shrinking table. (No social distancing here) :p

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Now don't they look all happy and clean?

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Into the cell holder to join all their friends.

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Here is what's left of their old coats.

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#3:
Pack #4 came out perfect with the Ah discharge at 185.68 with my new iCharger X8. The iCharger X6 I am using to keep an eye on the regen pack to make sure the packs stay in balance through this back and forth charge and discharge exercise. So far so good.
I have ordered a cheap 3s BMS just in case but so far the packs have been perfect without any intervention. Also if need be I can always use the X6 to run just a balance on the packs.

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Well that's it for today.
Pack 13 re-wrap duty tonight and then pack 14 tomorrow.

Wolf
 
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Wolf

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Update:

Found 2 more corroded cells that were replaced. Again no external signs of problems alsocapacity and IR were good.

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All 14 packs done 11 tested and 3 more to test.:)
Picture is of13 packs as 1 is being tested.

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Results of the packs is very encouraging as far as consistency in Ah is concerned.


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Now for the Lexan side covers and the cabling.

Wolf
 

Wolf

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Messages
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Update:

The last pack has been tested and as expected the results were right in line with all the others.
After over analyzing the results the deviation between the min Ah and maxAh of thepacks is 2.46%, not bad for a first pack build attempt.

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Good news the Batrium BMS has arrived and I will look forward to setting it up.

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Alright that's it for now.

Wolf
 

Wolf

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Update:

As they say idle hands make a devils workshop so as I am waiting for my Lexan side covers which have been cut by my glass shop.

image_enzzns.jpg

I now need to prepare them to mount to the battery packs, and I need a couple of hrs in the glass shop to cut holes and do some fine tuning.
That will probably happen this weekend.
In the meantime I am planning for the enclosure that I will place these batteries into.
Since I live in Maine and the temperature can go from one extreme to the other and the batteries are going to be in a shed and not in a "climate controlled environment" I need to take some things into consideration. Heat and Cold.
So with my limited knowledge of microprocessors I went to work.
My idea is to build a box to house the packs into that has some form of temperature management.
For the heat management the box will have 3 flaps/vents 2 on the sides and 1 on top. Under the top flap/vent there will be 2 or 3 fans.
The flaps/vents will be servo controlled and open around 23 C and the fans will kick in around 28C. I have not decided if I will PWM them for speed control relevant to temp yet but I am considering it.
For the cold management I will install 2 incubator heaters to maintain the box temperature at a minimum of 2C
The system will be managed by an esp32 module that will control 3 servos and 2 relays to accomplish this. The system will be independently powered by my secondary 12V solar system. The shed has its own solar panels,charge controller and AGM batteries (To be replaced with Li-io in the future)and is responsible for its own power consumption.
The first challenge was to get the esp32 to do all that which I have accomplished.
It has a DHT11 sensor (which will be replace by a DHT22 for greater temp range capabilities) for temp and humidity it is a rather slower reacting sensor so the servos and fans don't constantly kick in and out at the threshold temps. I suppose I can also debounce the readings in the sketch.
It has a 0.96in OLED attached soon to be replaced with a 1.3in OLED to display the status of the battery box and it also sends data to my influx db so the parameters can be monitored remotely.
Don't laugh at the breadboard but the prototype works.

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Also the influx data visualized in grafana.

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That's it for now

Wolf
 
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Wolf

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Sep 25, 2018
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Update,

So I went to the glass shop to pick up may lexan and put some curves on the corners.

I know how you all like pictures so I'll let them do the talking.

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With that done off to the shed for final drilling.

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And the final result

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Got 4 of them done. 10 more to go.

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Next, Batrium Longmon placement, cablinging between packs.
In my spare time thinking about battery box design and the environment control electronics for it.
Thats it for now.
Wolf
 

Wolf

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Allright another big update.

I was able to get 11 of the packs enclosed in lexan and am waiting for another 6 pieces to finish the remaining 3 packs.
Built the pack to pack jumpers and promptly ran out of heat shrink. Ordered this AM.
Glued Spacers on the longmons and fastened them to the packs. Wired everything together and initialized the Batrium and all looks good.
Now for some wire management cleanup for the longmons building the battery box and getting all this out into the shed so they can start to absorb some energy from the sun. :D

Pictures of the assemblyas always.

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Wolf
 

Wayne's World

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Jan 28, 2020
Messages
84
Hi Wolf. Great read. Few questions if I may...
Why Lexan and not just cheap Acrylic?
Are you screwing through the Longmon spacers into the holders between 2 cells?
What are the white rods you're using to clamp the laxan sides - Looks like some kind of nylon rod, with threaded ends and bolts I'm guessing?
How will you be mounting them in the shed. I didn't see any shed photos in this thread - Did I miss them?
When you want to add extra capacity, how will you achieve this?
Do you have a chart of every cell and its position, so you know what value to replace it with, or is every cell marked with that info, or its number?
Is there a meaning to the coloursused?

I dub these Wolf Packs!

Wayne
 

Wolf

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Wayne\ said:
Hi Wolf. Great read. Few questions if I may...
Why Lexan and not just cheap Acrylic?
Are you screwing through the Longmon spacers into the holders between 2 cells?
What are the white rods you're using to clamp the laxan sides - Looks like some kind of nylon rod, with threaded ends and bolts I'm guessing?
How will you be mounting them in the shed. I didn't see any shed photos in this thread - Did I miss them?
When you want to add extra capacity, how will you achieve this?
Do you have a chart of every cell and its position, so you know what value to replace it with, or is every cell marked with that info, or its number?
Is there a meaning to the coloursused?

I dub these Wolf Packs!

Wayne
You may............... :)
Why Lexan because I have a friend. Also it is very tough basically unbreakable, yea expensive, but as I said I have a friend.
He recommended Lexan as I was drilling the support holes for the nylon rods relatively close to the edge.

Yes I am screwing the longmon spacers between 2 cells it just makes it and the screws are very short. I drill a very small pilot hole and the screw just penetrates enough to hold. No fear of contacting the cells. Not that contact would be any good either way but it is on the negative side of the cells.

I bought nylon threaded rod in lengths and also nylon tube for spacers in lengths cut them to size. The nylon threaded rod was -20 thread and the Nylon tube was ID. Then I just added nylon nuts and washers cutting the threaded rod flush after tightening.


No you didn't miss the shed photos as I didn't post any of them yet. I am in the process of designing a battery box to house these cell in. It will be environmentally controlled. IE cooling with fans and heating for temps below 3 C. I will be using ESP32 microcontrollers to control the vent doors with servos, the fans will be PWM controlled with temp sensors so that energy consumption will be as low as possible. Additionally 2 100 watt 12 volt self-regulating incubation heaters to keep the box temp above 3 C. Fans and heaters relay controlled. All of these parameters will be posting to my influx database and visualized on grafana. The sketches for the ESP32s work (that took some time :p ) and I have the dashboard built. No data at the moment as I now have to go from breadboard to final assembly.

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The shed itself is independently poweredwith400 Watts of solar that charge at this moment into 1 massive AGM 12V telecom battery (to be replaced by Li-ion or some derivative thereof in the near future). The shed has no influence on the house system other than that it powers the shed cooling fans, lights, and the various sensors and "stuff".
Mounting the battery box is still in the planning stages. But as you can see I will be providing pictures at an ongoing basis.

Extra capacity is just a matter of another 14 packs tied in with the existing packs. Not sure what you mean by that.

I do have a chart of every cell in the build. Each cell has a number that correlates to the original spreadsheet into which it was entered at first arrival. The actual cells that went into the packs are also recorded in repackr with id # and which pack the cell went into. Also when I re-wrapped all the cells, that number, capacity, m? resistance and pack number was recorded on each cell. See my re-wrapping section in this thread. I do not however have the exact location of each cell within their corresponding packs.

The insulating wrap color was chosen as close as possible to the original and for some hair brained reason I wanted to keep same manufacturer and model cells close together.

Hope that answers some of your questions.

Wolf
 
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