18650 spot welding -how to- ULTIMATE REPOSITORY

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LikeToRideMyBike   100 W

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Post by LikeToRideMyBike » Mar 16 2016 11:55am

Random questions... Does anyone have any tips on soldering the balance wires and discharge/charge wires to the nickel. Techniques or type of solder. I've pretty much tried every technique I can think of. It's just hard to get the big wires to stick. I just use regular electrical solder from the local hardware store. 10AMW wire is extremely hard the solder to these thin strips of .7mm nickel. I'm having the damnedest time. Any help would be appreciated.

Thanks everyone

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Post by Offroader » Mar 16 2016 12:39pm

LikeToRideMyBike wrote:Random questions... Does anyone have any tips on soldering the balance wires and discharge/charge wires to the nickel. Techniques or type of solder. I've pretty much tried every technique I can think of. It's just hard to get the big wires to stick. I just use regular electrical solder from the local hardware store. 10AMW wire is extremely hard the solder to these thin strips of .7mm nickel. I'm having the damnedest time. Any help would be appreciated.

Thanks everyone
Need more information.

Are you pre tinning the wire?
How many watts is your soldering iron?
How big is your soldering iron tip?

You need a high wattage soldering iron with a big tip for the 10 gauge wire.

Have you been trying to solder the wire over a cell? I bet you are overheating the cells if you are having difficulty.

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Post by LikeToRideMyBike » Mar 16 2016 8:49pm

Offroader wrote:
LikeToRideMyBike wrote:Random questions... Does anyone have any tips on soldering the balance wires and discharge/charge wires to the nickel. Techniques or type of solder. I've pretty much tried every technique I can think of. It's just hard to get the big wires to stick. I just use regular electrical solder from the local hardware store. 10AMW wire is extremely hard the solder to these thin strips of .7mm nickel. I'm having the damnedest time. Any help would be appreciated.

Thanks everyone
Need more information.

Are you pre tinning the wire?
How many watts is your soldering iron?
How big is your soldering iron tip?

You need a high wattage soldering iron with a big tip for the 10 gauge wire.

Have you been trying to solder the wire over a cell? I bet you are overheating the cells if you are having difficulty.
Yeah, for the bigger wires I suppose I'll get an 80watt fat tip weller solder iron. Someone recommended one of those earlier. And some of that tinning paste as well. I just learned about that stuff today. And yes I most definitely have heated up some of the cells. I hope that I have not caused any permanent damage. Ughhhh :arrow: I'm most definitely losing sleep over this battery.

thanks again offroader

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Post by Offroader » Mar 17 2016 12:04am

80 watts is way too big to be honest, even for 10 gauge. It'll get too hot. Probably should have soldered the wire to the nickel before welding.

tinning paste? I don't think you need that, just get solder with flux in it.

Soldering takes lots of practice to get good at it. You probably shouldn't hold that soldering iron on the nickel strip attached to a cell for more than like 5 seconds max.

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Post by Skrzypas » Mar 17 2016 1:42am

Do you think it's a good idea to solder the thick wire a few nickel stripes and then spot weld the nickel to other nickel stripes being spot welded to the cells before?

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Post by litespeed » Mar 17 2016 7:35am

The bigger the tip the better always! That makes for the fastest solder time. If it will physically fit then bigger is always better just make sure you get in and then get out as soon as possible. The larger tip will hold more heat which in turn will heat the parts faster so there is less time that the parts are being heated.

Also I think tinning paste is always the best on any raw metals be it wire or sheet metals. Flux core it doesn't coat the wire well enough to get good flow. It's fine and single strand items like components on a circuit board but multi strand wire or not perfectly clean sheet metals flux is the best. Just don't over do it because it will look like a gummy mess and have a film that needs to be washed away.

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Post by mailer » Mar 17 2016 8:36am

DVDRW wrote:My first 18650 pack plan. 22s18p
Wish me luck! :D
If this is a battery for normal bike frame I hope you will make good and tight box for it. And don't forget the lenght of your pedals... You want to pedal too, I guess.

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Post by DVDRW » Mar 17 2016 11:43pm

Tried fit ok:
http://i.imgur.com/5g4kcfM.jpg

Why not stainless steel 0.2mm for cell tabs?
At least not corrode like steel
Cheaper than steel.
Not solderable i quess, and for very low current packs.
Or zinc coated steel?

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Post by Skrzypas » Mar 18 2016 3:32am

Magic pie + 22S?
Did anyone try this before?

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Post by Skrzypas » Mar 18 2016 12:26pm

Skrzypas wrote: https://www.fasttech.com/products/1425/10012815/3952701
Ordered 300pcs.

Until they arrive I'll continue welding negatives :P
Fasttech delivery time to central Europe: 3 and a half weeks.

Yesterday I bought some 0.1mm brass sheet for testing, and I find it a not so bad material for spot welding! It explodes more often than nickel, but is cheap, accessible and 20% more conductive.

Picture below:
Image

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Post by mistercrash » Mar 18 2016 9:13pm

Big post with 8 pics. I have been thinking of making large 1S modules with 18650 cells for a long time. I wanted to make them with things that can easily be found on the net and simple tools and a good spot welder. In this case, the pics show a 1S24P module. To demonstrate I used old tool pack Sony Konions, cardboard instead of Copper sheets and paper for Nickel strips and GPO-3 sheets. :D This would not be for a bicycle but for something bigger. Motorcycle, car, power station. The principle is the same for any parallel combination. Some will find this similar to the Tesla Model S modules, that's because it is.

First pic, 24 18650 cells in plastic spacers from Supower on ebay.

Image

Then I would cut 15 mm long pieces of 0.15X7 Nickel strip and spot weld them to the cells.

Image

Then I would bend the Nickel pieces upwards 90 degrees, like so:

Image

Then I would put some pieces of double sided tape on the plastic spacers, the pic shows four pieces of stuff used to stick area rugs to the floor.

Image

Then I would put a sheet of 0.0625" Copper cut to the correct dimension with 1/2" holes that align with the cells, slip it over the bent Nickel pieces like so:

Image

Then I would lay the Nickel pieces on the Copper sheet and solder them on the Copper. Shown here with some sticky tape.

Image

Once the other side of the cells is done, I would stick some sheets of 0.031" sheets of GPO-3 Fiberglass reinforced Thermoset Polyester on top of the Copper sheets, demonstrated here by the white sheets of paper.

Image

And finally, heat shrink the module. I like the Turnigy stuff sold by Hobby King, it is tough and thick.

Image

Positive and negative tabs sticking up, easily joined in series with a bolt and nut, tap in with a ring terminal for wires to a BMS. I also thought of shooting expanding foam in between the cells to pot the whole module. I found it easy to spot weld a piece of 0.25 mm thick Copper wire to a cell with my JP Welder, so a thin Copper wire could be used in place of the Nickel strips to have a fuse on every cell.

EDIT: I revised the process, I would put a sheet of GPO3 between the positive side of the cells and the Copper sheet. This way the cardboard rings shown in the pics stuck to the + side of the cells would not be needed. GPO3 is perfect for insulating the Copper from the cells. http://www.attwater.com/files/product_pdf/GPO3.pdf. I would not put a GPO-3 sheet on the negative side of the module between the Copper and the cells, it's really not needed, and it makes the module a bit smaller. And I would go with simple 0.15mm X 3.5mm Nickel tabs (0.15mm X 7mm split in half) to join the cells to the Copper sheets, it keeps the materials list simple, and I am sure that those tabs would act as a fuse in case of a short within the module. Also I would reduce the size of the holes in the Copper sheets to 1/4'' instead of 1/2''.

Any suggestions to make this better, please share your thoughts.

Thanks
Ray
Last edited by mistercrash on Apr 08 2016 11:25am, edited 7 times in total.
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Post by Relanium » Mar 19 2016 3:26pm

That's an awesome idea :D
Afcourse, for the bike you would need something like 5p, 10p or 15p module.
And maybe just glue cells together to save as much space as possible.

Would be nice to standardize modules.

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Post by DVDRW » Mar 20 2016 6:14am

insulation paper @nkon avaliable now.
Less waiting for European users :wink:

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Post by tomjasz » Mar 20 2016 9:42pm

Who's the most recent best source for a kg of nickel strip?
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Post by Offroader » Mar 24 2016 12:59am

Does anyone know the dangers of electrical shock when welding a 20s pack?

I've never got a shock from DC voltage, so I am not sure how easily I can get shocked from 20s.

Do I have to take precautions when welding a 20s pack?

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Post by Nobuo » Mar 24 2016 1:13am

72V can easily kill a human, the more chance the more amps you receive, with a li-ion battery you have all you need to die with. However human skin has enough resistivity to don't make this kinda happen, unless you have your hands or skin covered with an enough conductivity salts solution or similar.

Generally just keep your hands dry, you will always receive small scaring sparks once you are touching the whole 20s, never dangerous but it could make you drop the battery to the ground, and that could be VERY dangerous if you have a self-short and not a fuse system.

You will make the scare situations shorting series with metal tools / soldering / dropped strips, just wait to happen, it will happen the sooner or the later unless your OCD levels are over 9000

(I always work with insulated gloves)
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Post by Arlo1 » Mar 24 2016 1:23am

With my dry mechanic hands I don't feel 118v (28s fully charged). With 1 hand on the positive and my sensitive skin on the bottom of my arm on negative I felt 232v (56s)

When testing something with my HV lab supply cranked to 411 volts I got a sharp pointy part into my hand and the other had was on - and that Hurt good and a felt it for a minute or two...

It depends on your skin. How dry it is, If you have cuts or acid or sault or anything that will make you conduct better. I think 6s would kill you no problem when hooked to your body right. My attitude is always be careful and over 50v for the average person should require electrically isolated gloves.
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Post by kdog » Mar 24 2016 6:44am

Mistercrash- that rocks! I want a big EV just to put that idea in! So many good reasons to do it this way. Well done on the concept.
OR - I usually had no problems working on my 20s pack. But I got a nasty tingle if I spiked myself on the nickel or had wet hands. Be a little cautious.
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Post by Solarpower » Mar 28 2016 5:29am

Does anyone know the nickel strip thickness they use on laptop battery packs? Just finished my welder, and tried to weld some excess strips from recycled cells, but that didn't stick at all!
I got some pure nickel on the way from Ali.. :)

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Post by Nobuo » Mar 28 2016 9:37am

In laptop packs I've found always 0.3mm of pure nickel
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Post by Skrzypas » Mar 29 2016 12:44am

I've seen mostly 0,2 or 0,15 in laptop batteries. sometimes 0,3 but these were in ca. 5% of batteries I've met.

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Post by Solarpower » Mar 29 2016 1:51am

Thank you for the replies! I hope that it was some thicker strips I found, and not that my welder sucks :roll:

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Post by ian84 » Apr 02 2016 10:31pm

Awesome thread, subed!

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Post by ian84 » Apr 02 2016 10:52pm

reading from page one to here...

still got questions....

Want to make a pack be ablet o handle 50A continuous discharge.
for example 4s6p, battery cells are up to it in 6P config.

questions is the nickel strips... will it handle the 50A
Is it true not matter what voltage is... how many "S" current is still current... nothing to do with watts.. the current and heat is alway in relation to each other... and wattage does not effect the heat exchange ?

So, @ 50A current draw, with pure nickel (201), spot welded to connect all cells in series and parallels ... how will that hold up if I used:

0.2mm * 10mm
0.2mm * 12mm
0.5mm *10mm
0.5mm * 12mm

Noting that we can weld 0.5mm thick pure nickel safely without damaging the cells.
Also Noting that it will inside a PVC wrap. ( heat)

simply putting it is ... what can a 0.5mm strip offer ? and if we were able to safely spot weld two layers thru out the pack ( 1mm thick) what would that yield in current and temp.

And does a larger pack.. (more surface area of nickel) keep temp cooler... for longer than a smaller pack...(smaller surface area) or is current/heat, has not relation to the length of wire ( surface area) as to say.

with 0,5mm what amperage can we get with without a thermal run away.. sure heat will build up gradually..
let say Ambient temp.. at 25dgree C

I have tested a 0.2mm x 10mm ( ni 201) strips in two layers (.4mm) spot welding all along the length o 100mm

Results was.... @ 50A after like 10 seconds... it was way too hot to touch, then smoke and discolouration. test was done in open air... with just the nickel strips ( unwelded to anything)

Is this test different to if the strips were all spot welded ( same 2 layer) on a actual pack ..... then we tested with a 50A load... open air... no PVC.... will it yield same results or stay cooler... then just a the nickel strip with 50A put across it ?

trying to understand if my test is a good way of testing with all things equal....

nickel on its own Vs nickel spot welded on a pack....

Cheer.

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Post by Offroader » Apr 02 2016 11:40pm

This is one of the reasons I was happy to use copper wire for the series connections on my pack. I may peak at 140 amps on my pack. I would need a lot of nickel to move that current through my pack.

I use seven 16 AWG copper wires to connect my pack in series, or to handle a peak of 140 amps. You need 4 times the amount of nickel to move the same current as copper.

The main reason I used copper wire was because I wanted equal distribution of current through the cells on my odd shaped pack, the only way I found I could do this is if I used copper wire to make the series connections. All wire is equal length on each series group. This should allow perfect current draw through all the cells.

Image

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