New Powerwall in Romania


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cat23

New member
Joined
Dec 31, 2017
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18
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, untillast 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 Batriumbased, startingwith 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 morebatches of 1440p 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 finda considerable amountof 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, with400+ 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 consideringusing everything over 1700 mAh and 75% capacity left,at least until i will havea 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 majorproblem with using those1700-2000mah cells?
 
Welcome to the club! :D

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!
 
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 ACcopper pipe as busbar, will do some tests as soon as i have a sample to work with. The equivalent section area is around 15 squaremm, comparing with 18 square mmfor 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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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 sawthe 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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Ugh, that's one of the worst I've seen :s Maybe you can clean it up and resolder the connectors?
 
I resoldered the connector, the OPUS is chuggingon anew 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 powerby the electrolyte, but the stench was way worse.
 
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 :)
 
Salut George

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

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 (got300 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 aside quest :D I've noticed that the cells recovered from from similar laptops, firstonessold in Romania and the other onescoming from western EUare quite different:1900-2200 mAh vs2400-2800 mAh (original capacity)
 
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).
 
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 chineseCJ cells, 2200 mAh, from various compatible packs,all of them in 2100 2200 range. Worst of all, canadian made Moli cells.
 
Yes, those canadian i also remember. When i saw them i was expecting a lot from them... very wrong!
 
in order to destroy you opus take some TP4056 to charge first (are very cheap) ..... i use 6 of theme and let the cells to stay some 10-15 days and then test only cells with more then 4v

PS: you are not alone ..... salutari !
 
I already have 10 TPs, using them to make the initial charge on everythingexcept the Sanyos (there is some sort of temp protection on Opus, I think isgood to have it with Sanyo). The interesting fact is that LG behavedwell before the leak so.. probably bad luck.

Good to know DIY is not dead in Romania, really glad to see you here.
 
Nope, will wait until i have all the cells. i don't wantit's warranty to pass while sitting in the box
 
I managed to talk to my retailer and told me that at the end of April it gets new stock ......if this help you
 
Actually it might help, because i havejust got todayanother 50 or so packs, so i will get closer to my target of 560for stage one :D
Please keep me posted.
 
So, long time since my last update.

I reconsidered some specs for my powerwall. I upsized the packs from 40p to 60p,the busbars will be made from 2x2.5mm twisted copper (the 6mm AC copper pipe is overkill). Probably tonight i will finish the first 2-3 packs.

Pictures will follow soon.

LE


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After a hiatus of over one year, I restart working on the powerwall. The inverter arrived, not the one I originally had in mind, but a PIP2424MSE1. It found it quite cheap ebay, delivered from inside EU, sot it arrived in an amazing four day interval.

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I already have built 9 60p packs, so as soon as the spring arrives, i will pick 7, install the panels and start the initial testing.

I have two questions
1. The panels - I have in mind some 280W panels, but i am unsure about this max 80V MPPT - 105V max PV input. Sould I go with 2 panels in series or 3 (38,85V open circuit, 31,814 Vmp).
2. BMS - i want to use the Batrium, in the first months i'd rather not spend 500-600 eur on it. The packs are matched quite well, buit in 2018, harged, let to rest. After one year, the voltages are in .07 V range of each other. Is advisable to use them without Batrium this summer?
 
cat23 said:
I have two questions
1. The panels - I have in mind some 280W panels, but i am unsure about this max 80V MPPT - 105V max PV input. Sould I go with 2 panels in series or 3 (38,85V open circuit, 31,814 Vmp).
2. BMS - i want to use the Batrium, in the first months i'd rather not spend 500-600 eur on it. The packs are matched quite well, buit in 2018, harged, let to rest. After one year, the voltages are in .07 V range of each other. Is advisable to use them without Batrium this summer?

Welcome back

1) What are the other stats on the panels?
2) That's really nice to only have that small of a drift. At least you know you don't have any self dischargers. I would still recommend a BMS of some sort, even if a cheap one. But at least monitor voltages on a daily basis. Perhaps use those led volt meters on each pack to make that easier.
It's one thing for them to not drift while resting and back/forth current flow. It's another to start moving current around. You're making them work now so they may drift a little more.
 
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