Beginners Guide to Processing 18650 Cells | Cell Database


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Portuguese Powerwall in Poland
#1
Ok, let's start document this journey:
 
so my current status is that I mounted a bunch of sonoff pows around the house to measure several stuff, and a SDM120 for the overall usage of the house, and with a small python script insert it into influx and visualize it on grafana:



Since I have 2 tariffs (night + weekends cheaper), I needed a bit of scripting to calculate according to the time and active tariff what is the cost per measured appliance and the total spent on the house. 
So now I know exactly how much per month each of my loads costs me. That's is quite nice feeling.  

So, monthly the biggest consumption comes from the fridge (lodowka in polish Smile, the water heater panels (solar), and computers+router+projector (media). And since these are all small loads, I want in the first step offload them into the powerwall with a small but efficient inverter. 

I've been collecting laptop batteries for a few months and here's how my stats look so far:

I consider good cells above 1800mah (opus measured), BUT also if the capacity / original catalogue capacity is bigger than 80%. I hope by doing this I don't put into the powerwall cells which are near their end of life.



As you can see, it doesn't look too good. 

I contacted every laptop service around, but the price is rapidly going up, so it's becoming more difficult geting good cells from used laptop batteries, at least here in Poland.
Either they want too much for them, or the cells are not good enought for the powerwall.

I still have around 70 laptop packs to open, hope the stats get a bit better.

I decied to buy directly from a ebike guy 100x INR18650-29E unused (original capacity) for 1.42EUR/cell, to help me get to my first goal of 560cells for the 14s40p pack. 

I recently bought:

3x260w solar panels (still not mounted, just testing laying in the grass).
pcm60x

And made my first hook up yesterday.
What an incredible feeling, seeing the juice flowing Smile



I made a small 4s5p pack mainly to practise soldering and bus bars contruction and tested it:

 

But the pcm60x has a 15v limit, so it's time to go to the next step, which is build a 7s15p pack from my <1800mah cells and from cells with life capacity < 80%. This will help me further practising soldering and building for the ultimate goal of the 14s packs.

Let's see how that goes. I'll try to give more updates as it goes allong.
Please comment, specially if it's advice or critiques, insults are also tolerable Smile

I'de like to special thanks Peter for sharing his journey, and Daniel (daromer) for his incredible will to keep commenting and helping others. You guys are great!

Have sun
gulik154, shonalex, hbpowerwall And 2 others like this post
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#2
Awesome Frnandu, I'm following
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#3
I look forward to following your progress. Thanks for sharing!
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#4
Hey mate and welcome to the community,

Awesome to see another pack going up and how global this trend has become. 

A few soldering tips:

Use an adjustable heat soldering unit. They are well worth the extra money! When soldering to the cell and to thick copper, turn the heat up to its max. This allows you to heat the point of contact quickly and reduces the risk damage due to overheating. Also use thin solder that has a flux built into the core. The correct tools for the job will save you hours of frustration later. 

I use a Hakko FX-888D soldering station and MG Chemicals Sn60/Pb40, 0.025", with 2.2% flux solder. With the heather to 850 the solder melts away into beautiful little pools of shiny liquid in just seconds. You will spend hours and hours and hours using this soldering station, so it's a worthy investment.

Stoked to watch as you progress and happy building mate.

Cheers,

Chris
Frnandu Martiński likes this post
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#5
[diy Wrote:kgixkr[/diy] Inverted 18650 pid='8108' dateline='1499527533'] Hey mate and welcome to the community,

Awesome to see another pack going up and how global this trend has become. 

A few soldering tips:

Use an adjustable heat soldering unit. They are well worth the extra money! When soldering to the cell and to thick copper, turn the heat up to its max. This allows you to heat the point of contact quickly and reduces the risk damage due to overheating. Also use thin solder that has a flux built into the core. The correct tools for the job will save you hours of frustration later. 

I use a Hakko FX-888D soldering station and MG Chemicals Sn60/Pb40, 0.025", with 2.2% flux solder. With the heather to 850 the solder melts away into beautiful little pools of shiny liquid in just seconds. You will spend hours and hours and hours using this soldering station, so it's a worthy investment.

Stoked to watch as you progress and happy building mate.

Cheers,

Chris

Hello, thanks for the advice.

I followed daromer's advice and got mysef a 200watt soldering iron which has a thick mass.



I also got some flux pens similar to what has seen on average joe: 

https://www.aliexpress.com/item/Kester-9...0.0.AfGPbp

and so far is has been a surprising pleasure. It' really easy, as daromer explained in his video (thank you very much Daniel).

The only problem I seem to be having is that after soldering 20 cells the tip is already in this condition:

 

Would really appreciate some advice on how to not allow this to happen, at least not so quickly. Maybe too much flux?
shonalex likes this post
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#6
Its because you got your self an iron with pure copper. You need a tip that is plated with iron for instance for it to hold Smile

Dont worry when it comes to above. When you have wore it out you just exchange the tip for a new copper piece Smile
shonalex and Frnandu Martiński like this post
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
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#7
" The only problem I seem to be having is that after soldering 20 cells the tip is already in this condition:

Would really appreciate some advice on how to not allow this to happen, at least not so quickly. Maybe too much flux? "

(07-08-2017, 05:14 PM)daromer Wrote: Its because you got your self an iron with pure copper. You need a tip that is plated with iron for instance for it to hold Smile

Dont worry when it comes to above. When you have wore it out you just exchange the tip for a new copper piece Smile

I had the exact same issue after my test build. Since the tip is busted I took a Sanding machine too it and sanded off the first 3mm to get to a normal looking tip again but now it doesn't seem to get as hot. How come?

Daromer: So I can just put in a piece of copper with the same thickness and use that?
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#8
You can put in any copper yes and use it.

Note that there are 2 different tips. The ones with iron coating will last almost forever. As long as you dont file it! Its very important.
Copper tips on the other hand will wear out very very fast. and even faster if you dont threat it right. Like make sure its wet and use solder with less flux. I use 60/40 lead based and it seem to work pretty good. Not sure if non lead based will be more aggressive.

You can always put in your own copper tip so if you can get hand on some use that. My bigger iron is just normal copper tip to and it wears out but i have soldered 1000s of cells and even more stuff without problem. yes it digs out the tip fast but on the other hand the tip doesnt cost me much.
Frnandu Martiński likes this post
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
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#9
So I completed the 7s15p test pack just in time to catch the last sun rays today and load it a little bit, this was at around 19h, the sun was almost gone in the horizont and panel is rated 260w.

 

This 7s pack is still quite unbalanced, I'm leaving it connected overnight to my icharger for top balance.


I used repacker for calculating each series capacity to match, so let's see if this helps keep it balance without BMS.

I will then try to use it on an old UPS APC smart 600 and try to test its capacity on some AC loads.


Next step I guess will be to mount the panels on my terrace roof.
Since I want to have a variable tilt system for my south side panels, in order to easily change the angle 4 times per year, so it will require a bit of thinking, planing something simple but solid for strong winds.

For my location here's the optimal angles:
winter: 76°
summer: 23°
autumn and spring: 50°

Also next in order is to build a shed for my 14s packs.

I just noticed the batrium discount code that peter got us.
I've been undecided beetween the REC BMS and Batrium, so now have to decide until august 6 wether to order the batrium with free shiping.
hbpowerwall likes this post
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#10
So, a bit of an update.

Good news is I put up the 3 panels on my terrace roof. I still didn't come up with an solution for a variable angle system, so I just mount them fixed (13 degrees for now), but I guess until winter I'll have a bit of time to think of something that is solid.



I only connected 2 of them for now, since I need mor MC4 connectors for extension cable.

Looking at these first solar panels on roof gives me a very big smile on face Smile




Next I connected an old used UPS APC smart 600 to my 7s15p pack and it works, I've been pulling almost 300W and powering my router, laptop and projector, and this is an incredible feeling. Also it helps convince the wife to approve buying a good inverter for the 48v powerwall to feed the all house Smile




On the bad news side, I blew up a buck converter  from aliexpress:

Adjustable power supply 300w 



I don't understand it fully, since it should hold up to 40v on the input, and since I wasn't pulling anything from the pack. Maybe I just shorted it out, being uncarefully.
I unsoldered the caps, and will try to bring it back to life by puting new ones, since I'de like to use it to power my laptop directly without DC/AC/DC wasting.
If anyone has a good source for buck converters for 7s or 14s and around 10amps, please let me know.

Also on the bad side, my stats from salveging laptop cells took a big turn for the worst:



I've now tested around 800 cells, and these stats are not very encouraging, since the price of these laptop packs are getting higher and higher.

Still a bit of cells and packs to open and test, so let's hope and see what that will bring:



Next step is to build a shed for the packs, and decide on the batrium discount thing....what do you guys think? are you also considering takeing up on this opportunity??
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