18650 spot welding -how to- ULTIMATE REPOSITORY

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Post by Offroader » Feb 23 2016 11:07am

That looks pretty good, you are lucky to have such a rectangular pack to make it even. I have to solder a bunch of wires to each two cells to make everything even.

Copper strip makes sense to keep everything nice and flat.

Where are you going to get .2x8mm nickel? I'm yet to find a reputable source for 99% .2 mm nickel.

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Post by LikeToRideMyBike » Feb 23 2016 12:48pm

Offroader wrote:
LikeToRideMyBike wrote:Well, it looks like your suggestions worked Offroader. I filed down the weak pin quite a bite and gave it a little point. Not too sharp, but pointed. Then I raised it a little higher than the stronger pin. And when i apply pressure for the weld I tilt the cell toward the stronger pin. So far has put out consistent, even, strong welds. Thank you so much for the advise. So much!
My cells arrive the day after tomorrow. Tomorrow I will do more testing before I begin production, but I looks like I'm good to go. :wink:

But let me ask you this... Is it better to have your current high or your pulse high? For example: I can either have my pulse at 8p and my current at 6a, or I can have 6p and 8a for .15mm nickel. Either setting will work, but which one is better?
That is good to hear it worked. I ran into similar issues with my JP welder and also an issue of not being to get both sides welded strongly. I was pushing way too hard. By a bit of luck I somehow determined that all the inconsistency was how much pressure I was using. Surprisingly, nobody has ever commented on this once before in all the welding threads I read on the forum, which still surprises me because pressure seems to be a huge factor.

With the high current vs high pulse, I have actually asked this same question a few times already :D . Nobody has yet to give me an answer.

I think the issue is there are just too many variables when welding it is hard to give an answer.

Well, the best answer I think I got when asking the pulse time, was to experiment.Which I think holds true in your case.

With the JP welder we can't as easily adjust the amp setting like you can, we would have to add or remove batteries. Which I will actually be doing soon to try and figure out how best to weld .3 nickel.

What I would recommend is you get a disposable junk battery, like a C size battery or old 18650 and some extra nickel and keep testing the different settings. Just pull off the old weld and file the battery slightly to remove the old welds and keep trying the different settings until you see what seems to have the best welds (2 holes when pulled off without burning). If you weld at the tip of the nickel strip you can pull it off and weld again to the same strip to get a lot of uses.
I've welded like over 50 times to a single battery.
Great idea filing the practice cells down. I didn't think of that. I had already used them so much they were a mess. After filing I did some more testing. Is this the kind of welds I'm looking for? pushing slightly through the surface. And they hold firm. Notice how they are all even now. Whoohooo!
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Post by 999zip999 » Feb 23 2016 2:27pm

With all those spot welds is it getting hot ?

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Post by Doctorbass » Feb 23 2016 2:49pm

Mr Lowbank wrote:Hi All
Have been mining the Endless sphere for information to build a new pack for my Bomber #127. Thanks to forum members for all the great information.

I decided against 20s14p as it would be a tight fit, weigh more and I really don't think I need the amps. I'm hoping for Sanyo NCR 18650GA Cells but Tumich is out of the GA"s!!. Will be installing Max-E controller and have crystalyte 5405 and 5404 motors.
I have a JP spot welder on the way along with all the other bits I think I might need. After taking onboard all the info about building batteries I have come up with the following design. I'm interested in any comments.
Cheers Jon

Image
Excellent design!

I agree to say that the current share between cells is perfect.
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Post by Skrzypas » Feb 23 2016 2:52pm

999zip999 wrote:With all those spot welds is it getting hot ?
Nickel changes colors to what you see in about 400 and more deg. Celsius. Which means it must be getting hot (locally).

Obvious tip is to do only a single spot weld on one cell and then move to another cell, and come back to the first cell (for next weld) after finishing "the row".

What I noticed today is that (for recycled laptop cells) welding to the original tab-remainings is:
1. Much more random regarding the strength.
2. Much more colorful (welds look burned more)
3. Because of above: not recommended.

Best welds I get are on the original cell terminal area; the four spot welding points done by laptop manufacturer must be grinded (I use dremel). It is better not to grind the whole terminal but only these 4 points. These are my observations.

I also clean surfaces with extraction naphtha.

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Post by 999zip999 » Feb 23 2016 2:57pm

I imagine the shape of the tip and pluse or is it double pluse is it ?

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Post by LikeToRideMyBike » Feb 23 2016 3:05pm

999zip999 wrote:With all those spot welds is it getting hot ?
Yeah, the surface was hot, but this was just a laptop battery cell for practice only before the real deal arrives... Samsung 25r's. You think 3-4 welds would suffice?

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Post by Mr Lowbank » Feb 24 2016 1:02am

Punx0r wrote: Physical construction may be an issue since it looks like you're not using cell holders/spacers.
I tried for a long time to come up with a design that could use cell holder but will not fit in bomber unless you do what what Sigmacom did.https://endless-sphere.com/forums/viewt ... 14&t=61604
so it will be the hot glue and stiff Glass Epoxy sheet method.
Offroader wrote: Where are you going to get .2x8mm nickel? I'm yet to find a reputable source for 99% .2 mm nickel.
http://www.aliexpress.com/snapshot/7361 ... 0737082115
We will see
Doctorbass wrote: Excellent design!
Thanks Doc
I think I will make a jig to do all the soldering first for the series links, then spot weld to the cells last. that should make it go faster too.

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Post by Punx0r » Feb 24 2016 4:14am

JohninCR recently commented that upon disassembling hot-glued packs the glue peeled easily from the cell heat shrink. This may be sufficient for your needs, but I have wondered whether it would be better to add a layer of conventional heatshink to the cells to improve glue adhesion and provide better protection against chaffing. The downside would be the effort, a little extra pack bulk and lower thermal conductivity for the cells.

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Post by mailer » Feb 26 2016 9:07am

Hello ES forum members. I'm new on this forum and after a month of reading a lot of thing about EV I decide to register. I already have an idea of beginners EV but of course I need some tools and equipment first.

I already have a 30W Ersa welder, I ordered some extra heat shrink tubes for 18650 cells. I didn't decide yet if I will use glue to make a pack or a holder http://g02.a.alicdn.com/kf/HTB1XQRhIXXX ... s-lot-.jpg for more industrial look. As I read here the heat will better transfer with glue than empty air spaces with holders. I think it's more personal opinion of what to choose, but you can save some space with the glued cells. I will also buy some positive insulation paper gaskets.

I read the whole topic about welders. Because I'm from Europe I need 220V-240V version. There is a lot of different version on the internet a lot of them from China.
At first I was looking this one: http://www.ebay.com/itm/Battery-Point-w ... SwstxVUM1C
Then also recomended Suunko 709A and of course JP welder from user of that forum. But for now JP welder is not availiable any more.

I want to weld nickel stripes from 0.15 to 0.25 so I need a decent welder from which I won't get hurt. :D Any new (updated) suggestions?

Someone was asking for a link with CNC welder, here it is: https://www.youtube.com/watch?v=VtqGbpYbxaw

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Post by up0 » Feb 26 2016 10:27am

Hi Mailer,

> But for now JP welder is not availiable any more.

I am surprised the JP welder should not be available any more?
UPDATE: I just saw riba's post - I am sorry to hear that! Hope he gets well soon again!
Did you contact riba, who builds them with a PM?
He is a very nice guy - definitely worth supporting his project!
I have just bought a JP welder from him and it works beautifully!
I also like the idea of not having to store yet another bulky spot-welder box like the one you have linked.

If you cannot get a new JP welder, I could lend you mine once I am done welding my pack in the next ~2 weeks.
Depends on where you live - could send it fairly easy to France or Germany. The JP welder fits in a small package.
I can also offer this to others who read this later, if they don't want to buy a bulky device for a one-time project.

> nickel stripes from 0.15 to 0.25 so I need a decent welder from which I won't get hurt. :D Any new (updated) suggestions?

Here is a tip on Nickel: I would suggest using the recommended Aliexpress source from the first post: Best price/value.
But when I tried buying Nickel from them recently, they were temporarily out of stock (prob. Chinese New-Year)
So I tried this one from eBay, just to see if it is the real deal:
http://www.ebay.com/itm/271794492996
( If the link is outdated in the future, look for shop: superpower669566 )
They boast a certificate on their offer-page, and the Dremel/Spark and Salt-Water test were both good,
so it seems to be a valid alternative, in case someone doesn't want to buy via AliExpress or needs a small quantity.
The delivery took some time, but that was most likely also because of chinese newyear - just my bad timing.

Cheers, Ulli

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Post by markisses » Feb 27 2016 6:07am

Mr Lowbank wrote:Hi All
Have been mining the Endless sphere for information to build a new pack for my Bomber #127. Thanks to forum members for all the great information.

I decided against 20s14p as it would be a tight fit, weigh more and I really don't think I need the amps. I'm hoping for Sanyo NCR 18650GA Cells but Tumich is out of the GA"s!!. Will be installing Max-E controller and have crystalyte 5405 and 5404 motors.
I have a JP spot welder on the way along with all the other bits I think I might need. After taking onboard all the info about building batteries I have come up with the following design. I'm interested in any comments.
Cheers Jon

Image
Edit: I have misread Lowbank's diagram. I thought he only had 0.7mm^2 for the series connections but it's 7mm^2!! That should definitely handle the 40A per line if the desired amperage is 120A from the 12P Sanyo 18650GA cells. According to Nobuo's chart you can get away with only 2mm^2 of copper for your design.

I think you're going to need more copper for your series connections if you don't want
to bottle neck your current. It looks like you have the total current running through three
main lines.The copper you're using can handle 20A so 20A x 3 lines = 60A. This means
your pack design can only handle 60A without creating heat.
If you're looking for 100A/3
lines that's 33A pre each of your three lines. You'll need at least 1mm^2 (17AWG) of
copper for your 100A. You'll probably want more copper to match your cell output.
Each of those Sanyo GA cells can give you 10A each and 10A x 12P = 120A. That means
each of those lines should be able to handle 40A.
Last edited by markisses on Feb 29 2016 2:10am, edited 2 times in total.

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Post by Scottydog » Feb 28 2016 9:55am

I guess in that case if the strips were twice the width then that could solve that issue also and remain easy enough to handle, spot weld?

ps... like the layout! :D

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Post by Mr Lowbank » Feb 28 2016 6:33pm

Thanks for the comments Markisses. I did spend some time trying to get this right. but you have make me revisit this.
There are some rules of thumb that put copper at 2000A/in² which is 3.1Amps/mm² or 21.7Amps for my 7mm² copper strip. But this contradicts other information. Nobuo's table of tests with strips of nickel and copper wire has 1mm² copper wire at 19Amps. I will have 7mm² I understand that the current carrying capacity of a metal is effected by it's size and ability to shed heat and this depends on shape and thermal installation. A look on google tells me that 1/16 x 1/2 (20mm²) copper bar is good for 100Amp http://www.stormcopper.com/design/Ampac ... -Chart.htm So my thinking was 7mm² should be good for the 33Amps. Also Kdog got 10Amps out of .1x8mm (0.8mm²) copper strip I will have 8 x that.
kdog wrote: (The good news for myself and RTL is that 18amp through .1x8mm copper caused only very mild heating- prob comparable to about 8-10amps in the .2 nickel)
I didn't want to go to much thicker or wider as I plan to solder the copper and thought the bigger I go the harder it would be to solder ( get the heat into it).
Have I got this right? has anyboddy else have thoughts on this.
Cheers Jon

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Post by markz » Feb 28 2016 7:21pm

How do you know which winding is the primary and which is the secondary when taking apart a MOT for a spot welding machine?

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Post by Doctorbass » Feb 28 2016 7:31pm

Mr Lowbank wrote:Thanks for the comments Markisses. I did spend some time trying to get this right. but you have make me revisit this.
There are some rules of thumb that put copper at 2000A/in² which is 3.1Amps/mm² or 21.7Amps for my 7mm² copper strip. But this contradicts other information. Nobuo's table of tests with strips of nickel and copper wire has 1mm² copper wire at 19Amps. I will have 7mm² I understand that the current carrying capacity of a metal is effected by it's size and ability to shed heat and this depends on shape and thermal installation. A look on google tells me that 1/16 x 1/2 (20mm²) copper bar is good for 100Amp http://www.stormcopper.com/design/Ampac ... -Chart.htm So my thinking was 7mm² should be good for the 33Amps. Also Kdog got 10Amps out of .1x8mm (0.8mm²) copper strip I will have 8 x that.
kdog wrote: (The good news for myself and RTL is that 18amp through .1x8mm copper caused only very mild heating- prob comparable to about 8-10amps in the .2 nickel)
I didn't want to go to much thicker or wider as I plan to solder the copper and thought the bigger I go the harder it would be to solder ( get the heat into it).
Have I got this right? has anyboddy else have thoughts on this.
Cheers Jon

I think it's a matter of thermal dissipation.. in fact what limit the max amp is the temp rise of the conductive material versus the environnment it is used in. a 1mm2 cross sectional copper in a square shape should have a amp rating lower than a flat copper strip of the same cross sectional area. the flat strip have better surface to radiate all the heat witch allow more amp.

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Post by Offroader » Feb 29 2016 2:13am

I just tried to weld .3 99% nickel and I have discovered that there is no way I'm going to use .3 99% for my build. It is too thick and too difficult to get consistent welds. The welds burn too easily also. Then when I tried to up the power of my welder I blew the fets.

So now I have to find an alternative way to weld my pack, either use thicker .15mm nickel or .2mm 99% nickel if I can find it.

But the question is what size nickel strips do I really need?

My Sanyo 3500 has a max of 10 amps continuous. But I will hardly ever use 10 amp continuous.

The other issue is I'm going to use mostly copper wire to connect my cells in series, and only nickel strip to connect cells in parallel.

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Post by Nobuo » Feb 29 2016 5:48am

Offroader wrote:I just tried to weld .3 99% nickel and I have discovered that there is no way I'm going to use .3 99% for my build. It is too thick and too difficult to get consistent welds. The welds burn too easily also. Then when I tried to up the power of my welder I blew the fets.

So now I have to find an alternative way to weld my pack, either use thicker .15mm nickel or .2mm 99% nickel if I can find it.

But the question is what size nickel strips do I really need?

My Sanyo 3500 has a max of 10 amps continuous. But I will hardly ever use 10 amp continuous.

The other issue is I'm going to use mostly copper wire to connect my cells in series, and only nickel strip to connect cells in parallel.
Paralleling connections use too low current sharing, taking into account you are using new cells for the same model, you don't need even 0.15mm pure nickel. 0.1mm is more than enough for paralleling connections.

You need only the right size in the main leads cathode and anode terminals, depending on how and where you solder the main (or mains) leads wires. 0.2mm x 7mm (or equivalent) of pure nickel would be the minimum right mass for each cell.

For serial connections, 0.2mm x 7mm of pure nickel for each cell is the minimum for a right conduction using Sanyo GA.

I made an updated chart on the first post that took a good time to me for calculate, use as a guide
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Post by Offroader » Mar 01 2016 1:57am

Yes I did some calculations and figured it out, you are correct in that you don't really need all that thick of strip.

The main reason is that the parallel connections between cells are so short it is not worth the trouble to optimize.

For example, I calculated that with all the parallel cells tabs added together it works out to be 400mm of length for each 20s1p group.

in a 20s12p pack using .15 x7 mm of nickel you would have a .5 volt voltage drop.
in the same pack using .2 x 9mm of nickel you would have a .34 volt voltage drop.

So it doesn't make all that much sense to basically save .25% battery power by using really thick nickel.

So you guys pretty much have to make the calculations to weigh out the pros and cons of the nickel.

In my designed battery pack I use copper wire to the series connection so I avoid a lot of the difficulties with nickel plates,

Image
Last edited by Offroader on Mar 01 2016 4:11am, edited 2 times in total.

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Post by LikeToRideMyBike » Mar 01 2016 3:20am

Nobuo wrote:
Offroader wrote:I just tried to weld .3 99% nickel and I have discovered that there is no way I'm going to use .3 99% for my build. It is too thick and too difficult to get consistent welds. The welds burn too easily also. Then when I tried to up the power of my welder I blew the fets.

So now I have to find an alternative way to weld my pack, either use thicker .15mm nickel or .2mm 99% nickel if I can find it.

But the question is what size nickel strips do I really need?

My Sanyo 3500 has a max of 10 amps continuous. But I will hardly ever use 10 amp continuous.

The other issue is I'm going to use mostly copper wire to connect my cells in series, and only nickel strip to connect cells in parallel.
Paralleling connections use too low current sharing, taking into account you are using new cells for the same model, you don't need even 0.15mm pure nickel. 0.1mm is more than enough for paralleling connections.

You need only the right size in the main leads cathode and anode terminals, depending on how and where you solder the main (or mains) leads wires. 0.2mm x 7mm (or equivalent) of pure nickel would be the minimum right mass for each cell.

For serial connections, 0.2mm x 7mm of pure nickel for each cell is the minimum for a right conduction using Sanyo GA.

I made an updated chart on the first post that took a good time to me for calculate, use as a guide
I looked at the chart, but don't really understand what it means. Exactly what is <4.7a referring to when it says optimal for .15mm nickel? I know it has something to do with the amount of amps crossing between cells. And in parallel you can have thinner nickel, but in a series you need thicker nickel. But how do you come up with the current that's passing between cells. I'm really not following...

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Post by markz » Mar 01 2016 2:00pm

Use whatever nickel strips that weld good, ideally you want to go parallel first and series second. Series connection, you can solder on 8, 10 or 12 AWG wire, use whatever you have on hand, if its 14awg then double it up.

My suggestion would be to start with nickel strips, hook up to bike and ride it hard and see if the strips get hot.
If they do, start soldering wire. Thats how I would do it, skipping the riding part for testing and going straight to soldering wire, thats what I would do without researching it prior to this post.

I will be in your position within under a week. I bought some nickel from batterysupports which seem to be more expensive.
I have everything ready, just need to epoxy the top/bottom of the MOT (the Iron Core I believe its called), and build my electrode arms. Probably start that today, but it seems I am lazy these days.

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Post by Nobuo » Mar 01 2016 2:16pm

LikeToRideMyBike wrote:
Nobuo wrote: Paralleling connections use too low current sharing, taking into account you are using new cells for the same model, you don't need even 0.15mm pure nickel. 0.1mm is more than enough for paralleling connections.

You need only the right size in the main leads cathode and anode terminals, depending on how and where you solder the main (or mains) leads wires. 0.2mm x 7mm (or equivalent) of pure nickel would be the minimum right mass for each cell.

For serial connections, 0.2mm x 7mm of pure nickel for each cell is the minimum for a right conduction using Sanyo GA.

I made an updated chart on the first post that took a good time to me for calculate, use as a guide
I looked at the chart, but don't really understand what it means. Exactly what is <4.7a referring to when it says optimal for .15mm nickel? I know it has something to do with the amount of amps crossing between cells. And in parallel you can have thinner nickel, but in a series you need thicker nickel. But how do you come up with the current that's passing between cells. I'm really not following...
In an ideal situation, if the cells would be true twins and have the same heat dissipation properties, and all the BUS conductors the same IR and length, the current passing through parallel conductors would be absolute zero.

In practical uses there are several variables as each cells batch (chemicals percentages, age, mechanic construction), BUS length and mass differences, cell position (cooling capabilities), etc. That makes the cells having small differences in its behaviour discharging with different curves, making the less efficient cells being paralleled charged with higher SOC voltage ones.

Depending on your construction concerns and discharge rate this current will be low, or very low, but never relatively appreciable if you are using the same model of cells, and the battery have a "standard" build.

For example I can measure between 1mA to 10mA current sharing with unmounted testing li-ion same batch cells discharging at 2A, inside an ideal situation.

You could expect around a maximum of 200mA current sharing between one cell to its next mate, on a very bad scenario where cells come from different batch, one of them is more inside the pack with a greater instant temperature while a 3C discharge rate, so during the discharge it performs more efficiently than its mate on the edge of the pack.

With different model of cells, extreme cold temperatures, not good nickel conductor patterns, you could have a more intense parallel current share.


The chart indicates how a single nickel strip of the size indicated behave under that current values, under real situations, working inside a battery
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Post by Cowardlyduck » Mar 01 2016 5:04pm

Won't current sharing between cells depend on the placement of the series links?
i.e. if you only have 2 series links for 8 paralleled cells, then the cells not next to the series links will need to send their current through the nickel first before it reaches the series link.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by LikeToRideMyBike » Mar 02 2016 1:17am

I have a beginner question. :oops: So, I'm studying the chart showing the size nickel you need for a given battery pack. How do I determine the current levels/values, so that I can measure the heat generated by the cells? Am I looking at max continuous rated discharge current per cell? Could someone explain this to me in layman's terms so that I can understand thoroughly. I would appreciate it greatly!

thank you kindly

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Offroader   10 MW

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 02 2016 1:34am

What I still wonder about those amp ratings is they are based on continuous current. Nobody here is ever going to use continuous current on an ebike unless they took the bike on a highway and had OVS on their controller to actually push the cells to the max.

I guess that is why they have an acceptable rating. Kind of like an average of amp ratings you will use.

To figure out the current levels it will depend on how many battery amps your controller is set for, not the max rated discharge of the cells. Because your controller limits the current flow from your battery pack, and therefore each individual cell.

Then you will have to also determine how many amps flow between different areas on the pack, series connections may have more amps flowing through those areas than parallel connections. So you may very well have some nickel strips taking in more amps than others.

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