18650 spot welding -how to- ULTIMATE REPOSITORY

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Dec 14, 2017 2:00 am

Pure nickel strip confirmed!
Worlds cheapest?
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Dec 14, 2017 6:51 am

i orderd this one:

https://www.aliexpress.com/item/0-15-x- ... 96871.html

8mm wide and costs 59 USD. the 8mm fits better on most square spacers and if you need to overlap. it can also carry 15% more current.
when i get it i will fo the test and report back.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Cowardlyduck » Dec 21, 2017 6:24 am

Just had a scary moment building my monster 2.5KW pack for my Stealth Fighter.
I had turned the pot up pretty high and getting some decent strong welds, probably a bit on the strong side, but not too extreme. I was on my first layer of nickel which is possibly where I went wrong turning it up this high.
Anyway, I welded the negative terminal of an 18650 and it instantly sizzled (but only for a fraction of a second) with some clear liquid coming out of where I had just welded. At first I thought it could just be some left over alcohol from the cleaning I do with isopropyl alcohol wipes just prior to welding, but after wiping it away, more reappeared and I could see it very slowly seeping out from underneath the point I had just welded! :shock:
After wiping it away a few more times, and smelling it, I realised it was the batteries electrolyte leaking out :!: :shock:
The cell wasn't getting hot and it was one row in from the edge, so I carefully, but quickly cut the already connected nickel and pulled apart just enough cells to pull that one out. Replaced it now and re-welded in some more nickel and everything seems ok.

Anyway, I hope that serves as a warning to all, not to crank up the power too high with your spot welder just cause you can. I think especially when welding the first nickel layer that directly contacts the cell and especially on the negative side, you want to only give it the power it needs...nothing more.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by ChicagoJohn » Dec 23, 2017 6:24 pm

Hello. I'm new to ES and pretty new to 18650 technology. I'd appreciate any feedback on a project I'm working on. I am trying to spot weld 18650 cells using a 12V car battery (45Ah, 325CCA) as a current source. I have a Nano controlling pulse length and have verified accuracy with my oscilloscope. I'm using 0.1 X 8 mm pure Ni strip. I'm using 3 mm dia copper welding electrodes with rounded tips, 1 mm flats. After several trials, I think a dual pulse of 50 ms / 100 ms separated by 0.5 s works well. I've been putting considerable downward force (~10 lb) on the electrodes. Does any of this raise a red flag?

Until I have something I consider sufficiently reliable, I've been working with a piece of 30 gauge nickel plated steel to simulate an 18650 can. A problem I've had, and the main reason I'm posting, is that occasionally I get a dramatic result in which sparks of molten metal are thrown out six feet in any direction and I have a hole punched in the Ni / substrate. Inspecting the electrodes, I find a piece of Ni/substrate welded to one. Do you think this could be due to uneven force / inadequate force? Are there any tips or techniques that can be used to reduce the risk of this happening on an 18650 cell?

Finally, I am using a wood support under my metal substrate, and I note significant burns on it -- trying to replicate this effect by placing my soldering station tip on the wood for a second requires a tip temperature in the range of 700 - 800°F. Does this sound normal? I'm somewhat concerned about attempting this on an 18650 cell as things stand.

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Designs for best battery layout

Post by tomjasz » Dec 24, 2017 3:15 am

How about a half dozen layouts showing best practice and strip usage? 10s 12s 15s and 15s. Rather than w3 point out whats wrong we show whars best.
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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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by fechter » Dec 25, 2017 12:15 am

ChicagoJohn wrote:
Dec 23, 2017 6:24 pm
Hello. I'm new to ES and pretty new to 18650 technology. I'd appreciate any feedback on a project I'm working on. I am trying to spot weld 18650 cells using a 12V car battery (45Ah, 325CCA) as a current source. I have a Nano controlling pulse length and have verified accuracy with my oscilloscope. I'm using 0.1 X 8 mm pure Ni strip. I'm using 3 mm dia copper welding electrodes with rounded tips, 1 mm flats. After several trials, I think a dual pulse of 50 ms / 100 ms separated by 0.5 s works well. I've been putting considerable downward force (~10 lb) on the electrodes. Does any of this raise a red flag?

Until I have something I consider sufficiently reliable, I've been working with a piece of 30 gauge nickel plated steel to simulate an 18650 can. A problem I've had, and the main reason I'm posting, is that occasionally I get a dramatic result in which sparks of molten metal are thrown out six feet in any direction and I have a hole punched in the Ni / substrate. Inspecting the electrodes, I find a piece of Ni/substrate welded to one. Do you think this could be due to uneven force / inadequate force? Are there any tips or techniques that can be used to reduce the risk of this happening on an 18650 cell?

Finally, I am using a wood support under my metal substrate, and I note significant burns on it -- trying to replicate this effect by placing my soldering station tip on the wood for a second requires a tip temperature in the range of 700 - 800°F. Does this sound normal? I'm somewhat concerned about attempting this on an 18650 cell as things stand.
The weld times seem excessively long. This probably indicates the current is too low. Your battery sounds like it should work but possibly it's deteriorated or not adequately charged. Or there could be too much resistance in the circuit. With my graphene battery I'm welding .2mm nickel with a 8ms pulse.
"One test is worth a thousand opinions"

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by ChicagoJohn » Dec 25, 2017 3:26 am

Mine is rated at CCA 325A, an old battery from my Prius which may well now indeed be less than that. Yesterday, after changing the shape of my electrode tips from rounded to more pointed -- less surface contact area -- I was successful with a dual pulse of 30 / 60 ms in multiple welds at lower applied force without a mishap. I also noted a very dramatic reduction in burn marks on the wood substrate in my test setup. Still a far cry from 8 ms, and my nickel is 0.1 mm. Could you tell me the CCA rating of your graphene battery and what the shape of your electrode tips is?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Cowardlyduck » Dec 25, 2017 4:18 am

Not sure about your welder, but the JP spot welder I'm using recommends at least 500 CCA. I'm using a ~5 year old used 750 CCA battery with good success currently, but I do have to increase the pulse time as I do a round of welds as the battery gets weaker after a bunch of welds in rapid succession. This is even with it sitting on a float charge of 15V.

I recommend getting at least a 500CCA battery to try and use a lower pulse time.

Cheers
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by ChicagoJohn » Dec 25, 2017 1:22 pm

Thanks. I'll look into maybe a 600cca then.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by fechter » Dec 25, 2017 9:50 pm

ChicagoJohn wrote:
Dec 25, 2017 3:26 am
Could you tell me the CCA rating of your graphene battery and what the shape of your electrode tips is?
These are Turnigy RC Lipo batteries, mine is a pair of 2.2Ahr in parallel. It is 3s. These don't have CCA rating, but are rated for 130C discharge rate. Not cheap, but very lightweight and small.
Img_0571.jpg
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My electrodes are semi-rounded and have about a 2mm dia contact area.
"One test is worth a thousand opinions"

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by tomjasz » Dec 26, 2017 6:14 am

fechter wrote:
Dec 25, 2017 9:50 pm
These are Turnigy RC Lipo batteries, mine is a pair of 2.2Ahr in parallel. It is 3s
Not being very familiar with these, would you share an item number? I didn't find any 130C Graphene in my search. I have a 800CCA SLA but it's getting tired.
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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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by ChicagoJohn » Dec 26, 2017 10:05 am

fechter wrote:
Dec 25, 2017 9:50 pm
ChicagoJohn wrote:
Dec 25, 2017 3:26 am
Could you tell me the CCA rating of your graphene battery and what the shape of your electrode tips is?
These are Turnigy RC Lipo batteries, mine is a pair of 2.2Ahr in parallel. It is 3s. These don't have CCA rating, but are rated for 130C discharge rate. Not cheap, but very lightweight and small.

My electrodes are semi-rounded and have about a 2mm dia contact area.
Wow.. Amazing 570A. Will definitely look into. 600CCA lead acid ain't cheap either, and the form factor and weight advantage is awesome. I think I can find other uses for this battery too. Roughly how many welds do you do before recharging?

I found a graphene 3S 5000 mAh Turnigy RC Lipo for ~$58 incl shipping (hobbyking) that should do the trick. It is rated for 65C continuous and 130C burst. Not cheap, but a heck of a lot less 600 CCA lead-acid. Thanks for the info. I'm thinking that dropping the dwell time down to under 10 ms may reduce the area of heating and hopefully the size of the charring spots I've been seeing on my wood substrate. I'll play around with the electrode contact area and will post an update here when the battery arrives.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Dec 27, 2017 9:57 am

OK guys, so just here relly random the math formula to calculate the maximum amperage for your cable with a given cross-section in mm²:

Cross-Section of given cable (mm²) / 0,812(AWG20) * 11 (optimal °C) or * 16 (acceptable °C) or * 22 (poor/hot °C) => maximum amperage for your given cable.


For example I want to know how many amps I can push trough my AWG 10 cable so it becomes acceptable warm:

AWG 10: mm²: 5,26

-> 5,26 / 0,812 * 16 => 103,64 Amps.

How big is the cross-section of AWG x cable: https://de.wikipedia.org/wiki/American_Wire_Gauge
Source for the "0,812 value of a AWG20 cable": https://endless-sphere.com/forums/viewt ... 14&t=68005

(for questions or answer, please contact me via pm as I don´t look too often into this topic right here).

Cheers, Elias
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by tomjasz » Dec 27, 2017 10:35 am

ChicagoJohn wrote:
Dec 26, 2017 10:05 am


I found a graphene 3S 5000 mAh Turnigy RC Lipo for ~$58 incl shipping (hobbyking) that should do the trick. It is rated for 65C continuous and 130C burst. Not cheap, but a heck of a lot less 600 CCA lead-acid. s.
HALF as much as a lot of lead acid!
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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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Dec 28, 2017 5:59 am

DasDouble wrote:
Dec 27, 2017 9:57 am
OK guys, so just here relly random the math formula to calculate the maximum amperage for your cable with a given cross-section in mm²:

Cross-Section of given cable (mm²) / 0,812(AWG20) * 11 (optimal °C) or * 16 (acceptable °C) or * 22 (poor/hot °C) => maximum amperage for your given cable.


For example I want to know how many amps I can push trough my AWG 10 cable so it becomes acceptable warm:

AWG 10: mm²: 5,26

-> 5,26 / 0,812 * 16 => 103,64 Amps.

How big is the cross-section of AWG x cable: https://de.wikipedia.org/wiki/American_Wire_Gauge
Source for the "0,812 value of a AWG20 cable": https://endless-sphere.com/forums/viewt ... 14&t=68005

(for questions or answer, please contact me via pm as I don´t look too often into this topic right here).

Cheers, Elias
Can you do the same for nickel strip?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Dec 28, 2017 10:08 pm

Well I have had figured out once a genious formula for it, but I have deleted in from my calculator again so I tried it now.. Please be so kind and answer with a short "thanks Elias", or just "thank you", in case I could helped you somehow, as this makes me just happy when I could safe some time for someone else, so they don´t have to calculate the same stuff over and over and over :). It must be something about this:

Cross-Section of given cable (mm²) / 0,7 * 3 (optimal °C) or * 4,5 (acceptable °C) or * 6 (poor/hot °C) => maximum amperage for your given nickel strip for strips below 0,1mm*7mm (0,7mm²).



For nickel strips above 0,7mm² you have to add:

Cross-Section of given cable (mm²) / 0,7 * 3 (optimal °C) or * 4,5 (acceptable °C) or * 6 (poor/hot °C) + 0,4 ; 0,6 ; 0,8 *(cross-section of given cable/0,7 - 1) + 0,4 ; 0,6 ; 0,8 * 0,5

PS: The table of the first page is really unprecise at the Nickel Strip section, that´s why you have to calculate with so many extra-factors above 0,7mm² (everything bigger then 0,1mm x 7mm).

PSS: Its too late that I could check if its actually right. (Took me an hour in the middle of the night :roll: )



-Cheers, Elias
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by jonescg » Jan 04, 2018 3:28 am

This thread seems like a logical place to post about spotwelding troubles.

I'm trying to spotweld some 0.3 mm thick nickel to some cylindrical cells at work, but I think I might have found my welder's match. We have a SunStone capacitive welder and wound up to max power, it puts out just 200 Ws with a ~130 ms weld time (I think that's what it means).
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This 0.3 mm thick nickel won't have a joule of it. Successive belts do nothing.

The sheet was purchased from an ebay seller and it cost me about US$50 for four small sheets. It doesn't rust when submerged in salt water for 48 hours (even when hit with the dremmel) and it has a density of at least 8.9 g/cm3.

What do you reckon is going on here? The 0.075 mm nickel strip welds easily at 130 Ws. I guess it makes sense that more power is needed?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by spinningmagnets » Jan 04, 2018 4:06 am

Perhaps try installing a significant slit down the center of the nickel strip at the point where you are spot-welding. There is the possibility that some of the current is passing through the strip from one probe to the next, instead of passing through the steel shell of the electrode of the cell. You must force the spot-welding current to pass through the cell shell as it's only option.

I have had some success using a thin abrasive disc on a Dremel in order to achieve this.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by jonescg » Jan 04, 2018 6:49 am

Good tip - will try that tomorrow.

For a minute I thought I might have been sold some stainless steel, but my density calcs suggest it can't be. Not that my scales are that good either, but surely not so far out that 45.2 g was actually 40.0 g.

I suspect that it's just so much thicker than the usual stuff It's not having an impact.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Jan 04, 2018 9:14 am

you need a slit between the electrodes and for the love of all that is electric: replace those electrode leads with something WAY more beefy. 5AWG or bigger and shorten them to 2~3 feet maximum, measured from connector to tip. right now you are only heating up the cable.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by litespeed » Jan 04, 2018 10:43 am

I have a 800ws CD welder and with .3 mm I can definitely feel it when welding. I have all huge cables and use glidcop electrodes from sunstone. I personally think that over .2mm is kinda a waste used with a properly designed pack.

I'll betcha just going to glidcop would make all the difference you need though.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by jonescg » Jan 04, 2018 7:50 pm

Thanks for the tips guys - I normally work on pouch cells so this is all new to me.
I'm only using 0.3 mm nickel because that's what we happened to buy for a different (non battery application).
I'm 100% confident we have pure nickel, it's just too much metal for this spot welder. I'm going to order some 0.2 mm stuff from the USA and try that.
Cheers,
Chris

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Willow » Jan 06, 2018 8:06 pm

jonescg wrote:
Jan 04, 2018 7:50 pm
Thanks for the tips guys - I normally work on pouch cells so this is all new to me.
I'm only using 0.3 mm nickel because that's what we happened to buy for a different (non battery application).
I'm 100% confident we have pure nickel, it's just too much metal for this spot welder. I'm going to order some 0.2 mm stuff from the USA and try that.
Cheers,
Chris
Shorter thicker leads from the welder and slots in the nickel will help. I have tig welding electrodes in the ends of the copper rod - which I highly recommend over using the copper alone. Clean 'pinpoint' welds and no electrodes sticking to the material.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by jonescg » Jan 06, 2018 8:32 pm

You're spot welding copper there Simon? Good effort! What thickness?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Willow » Jan 07, 2018 2:12 am

0.1mm

does it easy, could do a little thicker... but no real need. Seeing very low resistance in the packs built like this.

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