Beginners Guide to Processing 18650 Cells | Cell Database


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Coolfx's powerwall
#1
After a bit less than 2 months collecting cells and reading a lot on different supports about 18650, powerwall, e-bikes, e-cars, it's time to get serious.

General idea

I plan first to build one or maybe two  7S array of 100Ah banks, charged by a PWM controller I have and 3 * 215Wc panels, as inverter i have my old 950W 24v UPS.
Next step will be PIP 2424 MSE or MSXE and 3 more panels.

Cells/packs

I already tested a bunch of cells, I have 350+ already in packs, maybe 50 under 1600mAh I keep for other projects and few hundreds cleaned waiting to be tested.

I design my packs to achieve 100Ah, sorting cells by capacity:
pack 1: 1600-1799
pack 2: 1800-1999
.
.
.
pack 7 : 2600-2799

I also build specials packs based on same source, like 40 or 60 cells bikes packs, I thing it's a good thing to keep theses cells together as they where all their previous live, tested capacity tend to confirm as their are all close.

These results at the moment in one Samsung 22F based pack and I have the same to process an next a 29F based one.

All my packs will have approx 10% capacity installed but not wired, so in case a cell break or a pack is a bit weaker I can add fuse wire to one or few cells without having to rebuild the entire pack.

Now I need to buy 4 or 6mm² solid copper wire for the busbars.

   

Don't hesitate to give your opinion if I go wrong on something
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#2
6 packs are now completed, two others are close to rejoign them.
Already tinned the cells, need to buy 6mm² copper for bussbar.

   
Glubux likes this post
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#3
This project was a bit asside for a moment but I came back to work last week and it's finally working.
It's not finished yet, needs final wiring between the PIP 2424MSXE and the batteries, electrical protections and a mounting plate for everything.

But at least I got the 3 * 215Wc panels on the roof, charging the packs and giving juice to the computer  Smile

It charged 941Wh the first day, 1187Wh the second where I find I faield the PIP charge configuration with 10 amps max, silly me !
So yesterday i got 1788Wh on a really nice day and it's going to be the same until tomorow.

At the moment everything is spread on in office ground but there are pictures of this working mess.

 

chriskool59 likes this post
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#4
After few weeks of use, and 3 weeks disconnected from solar when I was out of teh country, theses first packs looks good.
30kWh inputs and still no need to balance since the first week when I adjusted by connecting one more cell to a pack and two on another. Yesterday, fully charged aka 4v/pack they had 0.04v between lowest and highest !
Close to 3.3v/pack they diverge a lot more like 0.1v but it's ok as it's only need a top end balance.

Fuses, cables and mounting plate are for next week, I'm currently a bit out of money after visiting Peru but i'm sorting a new lot of cells I got 3 weeks ago. 
Around 66Kg of 18650, 58Kg of Lipo, not a lot of high capacity but I plan to use even 1400mAh as they are quite a lot, as my 1600mAh based pack seems as good as others it should be ok.
I also plan to use thoses Lipo as I have quite a lot of theses.




[Edit]Wow, did someone used a backup of the forum DB ? i had my reply pending because on the down server and now the message I was replying are gone o_O

Or did I inhaled too much gas from venting cells ? Big Grin[/Edit]
Korishan likes this post
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#5
From the beginning I know everyone praise randomness of cells but I had that idea and wanted to know how it will react. No one did it before so I had only one option to know what could happen.  Big Grin
Main idea was the possibility to use lower capacity cells, see if they do the job without having to repack everything if not. It's also easier to check if 1700mAh are good when they are not mixed.

IR is influenced by cells type too, high power cells have lower IR but lower capacity, so low IR can be low cap but brand new cells. I will continue to check theses packs, especially the low ends and see if they stay stable or die before others.

Spare cells are great, it's easy to just add one fuse wire to connect a new cell, but it cost some extra cells par pack so you need more cells and more slots on your holder. As I used 3 of them to balance my packs after the first few days of use I'm really happy to have that design. 

As I got a lot of Sony 1400-1500cells, I plan to make 2 packs of theses, they are 2Ah cells so it's just 30% lost. We will see what happen, if they die quickly it will be easy to just remove thoses packs.

Wow, did someone used a backup of the forum DB ? i had my reply pending because on the down server and now the message I was replying are gone o_O

Or did I inhaled too much gas from venting cells ? Big Grin
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#6
Yeap i did reply i think Big Grin

Yes i do random but i do random to certain degree
I do 1 string of low cap for instance 1700 if I have that. And then i do 1 string of 2-2.3 and so forth. Ie i try to pack them close enough but still not to mixed. Ie mix best of 2 worlds Big Grin
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#7
I'm pretty sure you were 2 to reply, forgot who it was.

You'r way is good, so you spread low cap with higher, but i'm not sur I want to keep low cap so I keep sorting by cap with the possibility to remove weaker and possibility to add even weaker (1400 ?) and see what happen without too much work.

After few weeks with 7 differents packs, from one with +-60cells 1600-1799 to another with +-38cells 2600-2799 it seems that packs with less cells (higher cap cells) need a bit more capacity (so 1 -2 cells more on 40-60 units packs). I think that's because thoses cells are a bit more stressed, let's say maybe with 30-40% more current so capacity decrease a bit.
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#8
Yes and no. I dont spread for insteance 1400 with 2000... In my sense i divide them into a certain amount of types and also then random them based on that

0-1000 -> Bin
1000-1500 -> Misc toy stuff for kids and myself
1500-1700 -> Misc lights and other
1700-2000 -> Low end powerwall packs
2000-2400 -> High end powerwall packs
2400-+++ -> I dont have many of those so havent built such packs as of yet.

If you have less cells you will have higher current. And higher current generally give you less useable capacity. So if you have one pack with 1700 and one with 2400 you will not get the calculated capacity out of it in practice.

Thats my idea about the random behind it and it of course also is based on that most of my cells have been 2100-2300 due to i got hold of a larger set of new packs that had such cells Smile
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#9
Next uptdate, I finally received my two contactors, diff-o-jump and auto breakers.

Every professionnals I asked how I can have an automatic system, using solar first for the whole house and also dumping excess to the water heater went with complicated system, at least 200€ or they had no idea how to do it.

After few hours thinking and looking online shop to find which products exists I had this schematic in my mind but no idea if it will perform as expected.

I proceded this way:

-Unpluged of his auto breaker the wire coming from the room where I have the PIP, using it to bring power without having to put new cables through the house.

-Pluged this wire into the new electrical box to the input of the diff-o-jump, another between diif output and the new auto breaker input and finaly  connected  breaker output to the NO input of the two contactors (2NO, 2NC) and to the coil of the first contactor.

-Pluged together the NC and NO output of each contactors (not the two contactors together!). So contactor 1 outputs go back to my old electrical box 


-Disconected inputs of few auto breaker and used contactor 1 to feed them. (Not a lot of rooms right now, it will grow with my solar and battery increase next month).

-Contactor 2 is not in use right now, useless until I will uprade my solar and batteries, it should be used only to dump energy to the water heater when battery are close to full, Arduino feedback will be used to control a low voltage coil relay, which will control the ac coil of contactor 2.

 

 

So right now I have my office, living room, kitchen (except hoven and hotplates who stay on-grid)on this modular system. If there are AC coming from the pip, contactor 1 alow it to feed the  rooms and cut down grid, when the PIP has a low voltage cut-off the contactor switch to the grid.
No need of expensive 1-0-2 contactors, theses Finder 223402304640PAS are doing a great job for 24€/pce.
Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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#10
Another string added, I'm now more comfortable with 5kWh even if it's still a humble capacity.

I'm processing the next strings and new solar pannels are coming on june 21, I still have to check I I can put easily more than 12*215Wc on the roof.
PIP 2424MSXE should be waxed out with 8 panels but as they are one 2 differents angles (122° and 322° azimut) it should be interesting to have more panels like 12-15 especially for winter.

Current setup: 21x 215wc poly, 7.5kWh 7s 18650, PIP 2424msxe.
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