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New Powerwall in Romania
#1
Hello guys. My name is Catalin and i'm on my way to build a powerwall (more of a powershed at the moment) in my hometown Craiova (RO).

Couple of years ago I've got an Opus C-3400, decided to start testing and sorting 18650 cells. I had an idea about what I want but not very sure how to do it, so it was more of a side project, until last year, when i found Pete's hbpowerwall channel on youtube and a lot of things start to clarify soon after.

My target is a 48V system, PIP and Batrium based, starting with a 1kw solar array and adding a wind turbine as soon as the initial setup proves to be stable (and of course more solar panels to be added at a later stage).

Now, for the battery packs. I'm planning to have a 14s40p for a quick start, adding more batches of 14 40p packs in the process until i reach 14s120p. The main issue with this is cell availability, considering the fact that my city is not that big or economically important to be able to find a considerable amount of laptop batteries. Thing are looking even worse when i put in balance the fact that i work in a computer repair shop and I already went through my supply of dead battery packs. More or less, i have around 150 tested cells, with 400+ more untested and around 50 more packs on the way. From those tested cells, 30-35 percent are dead, failed the self discharge test or under 1500 mAh (under 1500 go directly to my "other projects" bin). The "good" ones are from 1500 to 2500 mAh (according to Opus).

And here is where i really need your opinion. I am considering using everything over 1700 mAh and 75% capacity left, at least until i will have a more consistent flow of cells coming in. I see most of you don't use cells under 2000 mAh, but i cannot afford this luxury for now. In this first stage, the bank will not be pushed hard (mostly because of the initial 40p layout), probably around 500-700w constant draw, with computers, TVs and led lights as load (no inductive motors or anything with high inrush current).

Do you see any major problem with using those 1700-2000mah cells ?
Korishan, DeMonte Johnson, cmg_george like this post
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#2
Welcome to the club! Big Grin

There's no major problem with using cells of 1700mAh. That's perfectly fine. If you know your packs limitations and stay within those boundaries, you're good to go. Keep on trudging forward and you'll have a house wide system soon enough!
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at https://discord.gg/c7gJ5uA
(this chat is not directly affiliated with SecondLifeStorage)
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#3
Just began presoldering the first 40 cells. I used a Weller WES51 with ETDD tip and lead free solder. Took around 5 minutes for 40 cells, worked very well, cells didn't get warm at all. 
I'm thinking to use 6mm diameter, 1mm thick AC copper pipe as busbar, will do some tests as soon as i have a sample to work with. The equivalent section area is around 15 square mm, comparing with 18 square mm for 3x6 busbar, but i will be using 40 cells per pack, so i think will be more than enough, considering that i can get it almost for free.
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#4
Photo 
Couple of days ago one LG cell decided to leak while in my OPUS. Nothing to warn about this, cell looking fine, no corrosion, 2.70V, low temp. It happened one hour into the test, the smell alerted me. 

After I opened the OPUS, i saw the cell leaked directly onto the power connector, literally melting it, eating it's way through the PCB. After I changed the connector, i had to rework it two more times, as the electrolyte soaked the PCB fiber, shorting the power plane. The plastic box and the fan connector took some damage as well. 

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#5
Ugh, that's one of the worst I've seen Confused Maybe you can clean it up and resolder the connectors?
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at https://discord.gg/c7gJ5uA
(this chat is not directly affiliated with SecondLifeStorage)
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#6
I resoldered the connector, the OPUS is chugging on a new batch of crappy Sanyos as I type this.
The biggest problem was with the electrolyte, it was absorbed by the pcb substrate and turned it conductive. I had to scrape the pcb between the positive and ground traces until i removed all the contaminated material (now there is a hole in that area).

Indeed, some impressive display of power by the electrolyte, but the stench was way worse.
Korishan and hbpowerwall like this post
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#7
Hi, good luck with the build.
What model of invertor are you considering? Maybe we can make a combined order for the invertor?

PS: Salut, ma bucur sa mai vad si romani pe aici Smile
costty likes this post
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#8
Salut George

I'm considering some ebay sellers, one of them offers delivery from Belgium, this way avoiding the problems with the nosy and slow customs. 

For the moment, i'm not very concerned with the inverter because i still try to get the first 560 cells for the initial setup (got 300 by now). I purchased some 30-40 packs with 5 lei (1.1 eur) per pack but unfortunately some of them have water damage an most of the intact ones have Sanyos, so the potential harvest is low.  

And an interesting result of a side quest Big Grin  I've noticed that the cells recovered from from similar laptops, first ones sold in Romania and the other ones coming from western EU are quite different: 1900-2200 mAh vs 2400-2800 mAh (original capacity)
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#9
Unfortunate the quality problem i had it myself also! Initial i tooth is just bad luck but last batch i got it from UK and 70-80% of cells are over 24000mAh(after capacity test!) it was more that 5RON but the quality as also much better!
I had in focus also the seller from Bergium but it does not have the model i want: PIP-5048MS so i'm considering a order from Taiwan.

Any way, 5RON is good, in general i get 6-8RON from the ones ordered locally. Lately i just don't offer more that 7RON (this is price limit).
560 is not that far... good luck! My current count is: 1400 + ~300 unpacked (some details here: https://secondlifestorage.com/t-CMG-s-PowerWall).
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#10
Me too, I would pay more if i could get better quality packs, because i have 300 good cells and 140 bad cells + 120 1000-1500 cells . Until now, I am surprised in a good way by the chinese CJ cells, 2200 mAh, from various compatible packs, all of them in 2100 2200 range. Worst of all, canadian made Moli cells.
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