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any way to create packs without soldering?
#11
Or learn to solder, if solder gets older than 6 months+ the resin inside hardens out(oxigen), and its useless.
Take a 50cm off and throw that away.
I had a solder wire of a kilo, bought 20! years ago, i had to take 1 meter of to reach the "good" part again.
For soldering cells, take a 100w soldering iron.
But make your choice wise, you got 100w solder irons that reach to 500 degrees celsius!
They will oxidise the lead, not vape(lead fumes) it, but oxidise, buy a cheap one for around 7-10$ at ~300-350 or something.

Both will work on cells, but its better to buy one at 300-350C.
You will be fine.
And its easier to repair if something happened or you want to check the whole pack after 1 or 2 years.

But this is my opinion, get a second thought on this.

Best

PS never ever use s39 or simular....NEVER...it will eat your copper away, and give you "contact disturbance"(freely translated).
Despite all those ytbyeee vcr's don't use it, learn to solder without that stuff
Still learning English. Learning Li ion and solar technology.
+/- 3500 Li ion cells harvested, none checked and counting.

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
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#12
A serious DIY youtuber @jehugarcia has initiated a project to build full scale powerwalls using stackable circuit boards with 18650 cell holders. Its gotten pretty sophisticated to include BMS(s) and LED based charge levels etc. There is expense/work to buy/put-together these PCB units BUT... you can just snap in the cells Smile
Here's a sample youtube https://youtu.be/sjqQZSRlWAA to give you the idea. On his site he has several youtubes and place to purchase.

*I am NOT pushing this, just seemed like a reasonable alternative to soldering for a serious powerwall if $ is not an object.
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#13
Those boards are not designed to be used at the currents required for a powerwall. They are also prohibitively expensive to build a powerwall from. They are fine for small projects. But anything requiring more than about 15A it is no good. rev0 (here on the forum) is the original builder and tester of those boards. Please check out the threads pertaining to the "Jehu Board" before using them.

There is also someone else who made an offshoot of this project, and they did a worse job in the design by not using enough trace width and/or solder traces to handle the current. These things are going to get someones house burned down, I'm afraid.


Ohhh, just took a quick look at the video. This is one where he is paralleling cheap chinesium bms units. No 2 chinesium bms units are identical, and they will eventually fight each other, especially under heavy load/charge. When 1 unit shuts off, the surge of current through the other 2 could blow them out before they trigger.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

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#14
(05-23-2019, 08:44 PM)OffGridInTheCity Wrote: *I am NOT pushing this, just seemed like a reasonable alternative to soldering for a serious powerwall if $ is not an object.

If $ isn't an object then it make much more sense to buy lots of ex EV cells and simply bolt them together, I fail to see any merit in spending a significant fraction of the projects total cost on electrically suspect holders.
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#15
+1, used a controlled welder
Actually doing spot welding is pretty easy
- hold tips firmly on nickel strip
- press the foot pedal
done!
Others have experimented a bit to find the right settings on some dead cells.
Or like said above, a bigger soldering iron is an easy cheap fix.
Running off solar, DIY & electronics fan :-)
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#16
So I also went the homemade spot welder from a car battery and solenoid route. I'm not going to openly suggest it as a better alternative to an actual spot welder off the shelf but I can tell you that I actually had great success with it. That is to say, after I blew thru about a dozen cells and trained my finger to hit the momentary switch for the exact precise millisecond I had great success with it. So just be warned, it's much more dangerous to go that way but, if you feel confident you know what to do, it could be a viable solution for a smaller pack. I think mine cost me no more $60 and one hour of assembly time all in.

Just a couple of things, a lotta the builders on YouTube that show how they created theirs say they don't have to charge them very often, however that wasn't my experience at all. I probably had to charge it after about spot welding every 60 cells. I think my battery was much smaller than theirs perhaps. I would suggest taking it outside when charging for safety sake.

Also, you REALLY need to be aware of cold cranking amps on the battery and will probably have to experiment with what works for your project. Again, on YouTube, a lot of the builders says you can go up to like 600 CCA but I definitely needed to stay below 300 CCA otherwise I was burning thru almost anything. My battery was also more of a tractor Lawn & Garden battery, rather than a true car battery.

Then I would suggest mounting the momentary switch to anything that is stationary and easy to reach. Keeping it free and open and just held in your palm makes it way too easy to hold down that button for just a millisecond longer thus getting a bad weld or blowing thru the cell itself.

Finally, a pro tip is to make your welding contacts, whether that's on pivoting arms or more of a welding pen, be spring loaded. I learned the hard way that that makes things SO much easier in terms of correct pressure and getting good contact between the copper, nickel and cell cathode/anode. Both suspension springs and compression springs are super cheap and made the welding process so much more enjoyable. Pictures of my DIY spring loaded pen and arm monstrosity are below (ended up making both for convenience sake and I was not going for looks or professionalism as you might be able to tell).



FYI I was never able to properly weld fuse wire or glass fuse legs directly to the battery anode, so, instead, I would just solder one leg of the fuse to a small tab of nickel and then weld that nickel tab to the anode. Definitely more time consuming than just using a spot welder that can successfully weld thin wire but, hey, it worked. For my larger packs, I may end up getting a real spot welder.
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#17
Nice little DIY setup ya got there.
The reason you have to recharge so often is because you are using the lawnmower battery, and something that is 300CCA range.

I would recommend going a little further into the project and build the proper timer adjustments with the FETs and triggers so you can use any battery and really dial in the duration needed.
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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 Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#18
(05-29-2019, 11:03 AM)Korishan Wrote: Nice little DIY setup ya got there.
The reason you have to recharge so often is because you are using the lawnmower battery, and something that is 300CCA range.

I would recommend going a little further into the project and build the proper timer adjustments with the FETs and triggers so you can use any battery and really dial in the duration needed.

Thank you sir and, yes, agreed, for big packs or any type of consistency, I definitely need to get some type of timing integrated into it. This is the part where I wonder if it's worth it taking the time to source and learn everything or if I just roll the dice on the sunkko 709AD version that's currently in the marketplace board. Only have 110V plugs though so kinda concerned about that since everyone seems to say that version is real weak. I can't seem to find the kweld in stock anywhere either so we'll see.
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#19
(05-30-2019, 12:52 AM)OhmGrown Wrote:
(05-29-2019, 11:03 AM)Korishan Wrote: Nice little DIY setup ya got there.
The reason you have to recharge so often is because you are using the lawnmower battery, and something that is 300CCA range.

I would recommend going a little further into the project and build the proper timer adjustments with the FETs and triggers so you can use any battery and really dial in the duration needed.

Thank you sir and, yes, agreed, for big packs or any type of consistency, I definitely need to get some type of timing integrated into it. This is the part where I wonder if it's worth it taking the time to source and learn everything or if I just roll the dice on the sunkko 709AD version that's currently in the marketplace board. Only have 110V plugs though so kinda concerned about that since everyone seems to say that version is real weak. I can't seem to find the kweld in stock anywhere either so we'll see.

Check out this thread - https://secondlifestorage.com/t-Spot-wel...-right-one
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#20
(05-30-2019, 01:49 AM)Geek Wrote:
(05-30-2019, 12:52 AM)OhmGrown Wrote:
(05-29-2019, 11:03 AM)Korishan Wrote: Nice little DIY setup ya got there.
The reason you have to recharge so often is because you are using the lawnmower battery, and something that is 300CCA range.

I would recommend going a little further into the project and build the proper timer adjustments with the FETs and triggers so you can use any battery and really dial in the duration needed.

Thank you sir and, yes, agreed, for big packs or any type of consistency, I definitely need to get some type of timing integrated into it. This is the part where I wonder if it's worth it taking the time to source and learn everything or if I just roll the dice on the sunkko 709AD version that's currently in the marketplace board. Only have 110V plugs though so kinda concerned about that since everyone seems to say that version is real weak. I can't seem to find the kweld in stock anywhere either so we'll see.

Check out this thread - https://secondlifestorage.com/t-Spot-wel...-right-one

That's definitely good info, thank you. I didn't even know about the malectrics unit and seems like a lotta people on here like it. I'll be checking that out for sure.
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