JP spot welder

[riba2233]

Yeah, in that case you would use a transfromer and have a welder like DN-5, but still, I pull 2000 A at 10 V from my batteries, and that's 20 kW, and that will trip most breakers. That's 166 A on 120 V, although for a short time, but still. So transformer based welders use lower current but have longer pulses, and we want opposite. Also, such large transformer will weight almost as batter, so there's no point. And I would have to ship 15 kg package, so there goes the cost effectiveness. Not to mention the price of such transformer

 

[Rodney64]

Riba, what nickel should I use for 72 volt and capable of 80 to 100 battery amps for short bursts.

 

[riba2233]

I always recommend welding cells in parallel with thin nickel, and then soldering them in series with adequate copper wires, but if you want to use only nickel, than you can use 0.15 or 0.2 mm nickel sheets, like madin88 used on his pack.

 

[Allex]

Rodney, I will soon build battery for Flux samsung r25, will use 0,2*8mm nickel everywhere, and beef upp the last rows with copper wire.

 

[Rodney64]

Thanks Alex

I have my cells 25r they're still in Melbourne but I haven't ordered nickel or battery cases yet.

 

[arek_arecki]

I plan to use a soft copper sheet 0.1x7-8mm samsung 25R welding cells , if only welds are strong enough. For this section of copper 0.7-0.8mm ^ 2 amps max is 15-17Amper, for comparison, pure nickel 0.15x7mm is 4,7Amper, nickel plated steel 0.15x7mm is 2,3Amper

 

[ridethelightning]

I always recommend welding cells in parallel with thin nickel, and then soldering them in series with adequate copper wires, but if you want to use only nickel, than you can use 0.15 or 0.2 mm nickel sheets, like madin88 used on his pack.

have you tried using 0.2mm copper? can it be done?

for high discharge packs, would copper not be better on the paralelle connestions and on the cells for minimising total pack resistance?

as nickel has like ~6+ times the resistance of copper...or is it not critical when you have say, 20-30A travelling through 0.2x8mm Ni strip, =1.6mm square?

(tabs on the cells)

 

[riba2233]

Current does not flow in parallel direction, so that's irrelevant, but you need adequate area for series connections, that's why I recommend copper. I haven't tried 0.2 mm copper because I don't have it But if someone does, he can send me a letter and I can try.. 0.1 works without a problem, but is to volatile and lokes to break. 0.15 would be a good compromise, but still, I don't like and don't recommend welding copper, even though it works.

 

[ridethelightning]

Current does not flow in parallel direction, so that's irrelevant, (quote)

sorry, i meant where the current flows out of the cells, ie. the taps on the cells themselves.

 

[riba2233]

Ok, I get that But still, if you put copper conductors between cells, path between cell pole and copper conductor is only few mm of nickel, so negligible.

 

[TheBeastie]

have you tried using 0.2mm copper? can it be done?

for high discharge packs, would copper not be better on the paralelle connestions and on the cells for minimising total pack resistance?

as nickel has like ~6+ times the resistance of copper...or is it not critical when you have say, 20-30A travelling through 0.2x8mm Ni strip, =1.6mm square?

(tabs on the cells)

I was a bit surprised by this statement so I tried looking it up... and it seems somewhat true, seems to be Nickel has 3 times more resistance then copper
https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
http://chemistry.about.com/od/moleculescompounds/a/Table-Of-Electrical-Resistivity-And-Conductivity.htm

But that difference is still pretty small, the main reason nickel is always used in these situations is that it doesn't corrode compared to copper. Thats why nickel coins are always nice and shiny but copper coins are deep browny even sooty covered color or even worse they go green, and always have that amazing transformation when copper coins are dipped in cocacola or tomato source..
These resistance tests are always done with fresh clean metal.. but I think if it was done with moldy metals nickel would always win...

 

[ridethelightning]

have you tried using 0.2mm copper? can it be done?

for high discharge packs, would copper not be better on the paralelle connestions and on the cells for minimising total pack resistance?

as nickel has like ~6+ times the resistance of copper...or is it not critical when you have say, 20-30A travelling through 0.2x8mm Ni strip, =1.6mm square?

(tabs on the cells)

I was a bit surprised by this statement so I tried looking it up... and it seems somewhat true, seems to be Nickel has 3 times more resistance then copper
https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
http://chemistry.about.com/od/moleculescompounds/a/Table-Of-Electrical-Resistivity-And-Conductivity.htm

But that difference is still pretty small, the main reason nickel is always used in these situations is that it doesn't corrode compared to copper. Thats why nickel coins are always nice and shiny but copper coins are deep browny even sooty covered color or even worse they go green, and always have that amazing transformation when copper coins are dipped in cocacola or tomato source..
These resistance tests are always done with fresh clean metal.. but I think if it was done with moldy metals nickel would always win...

sorry, yeah not quite shooting straight there... its a realationship of 1.68(copper) to 6.99(nickel)

i was surprised when i first got wind of this too.

as to the difference between corroded copper or clean, id say it wouldnt make much difference providing the contacts were welded, as the inside of the conductor woud be un affected.
I think Nickel is popular for battery spotwelding cause it is easier to weld and the surface stays fairly clean for welding.

I noticed how much harder it was to weld copper when tessting a dn10.

because it conducts heat away so fast, it requires MUCH more power in a short pulse to create enough heat to make a weld.
also, to compound this, because it has such good conductivity (or low resistance,) the current going through it needs to be MUCH more in order to create enough heat to make the weld.

they use Nckel coated copper in dewalt cordless drill packs I believe. i have done some testing with some, and was thrilled to finally get a good weld on an old AA alcaline battery.

this to me seems like the best material, between 1.2 and 0.2mm.

 

[TheBeastie]

[
sorry, yeah not quite shooting straight there... its a realationship of 1.68(copper) to 6.99(nickel)

i was surprised when i first got wind of this too.

as to the difference between corroded copper or clean, id say it wouldnt make much difference providing the contacts were welded, as the inside of the conductor woud be un affected.
I think Nickel is popular for battery spotwelding cause it is easier to weld and the surface stays fairly clean for welding.

I noticed how much harder it was to weld copper when tessting a dn10.

because it conducts heat away so fast, it requires MUCH more power in a short pulse to create enough heat to make a weld.
also, to compound this, because it has such good conductivity (or low resistance,) the current going through it needs to be MUCH more in order to create enough heat to make the weld.
.

Yeah I also think that the 18650 cell can cylinder construction shell must be as much as %50 nickel as well for the sake of rust proofing ( I am guess the rest would mostly be steal for strength). This also helps make it an easy weld as nickel will bond to nickel more easier then two different types of metal.

Just looking around now... and Googling "18650 cylinder case materials" brings up a bunch of links saying "nickel plated A3 steel"
Looking up "A3 Steel" gives this which I think is a pretty good description, basically A3 steel is %95 iron with %5 other alloys mixed in.

http://www.azom.com/article.aspx?ArticleID=6219
The chemical composition of A3 tool steels is predominantly Iron (Fe) with the following elements outlined in the table also present:

Element Content (%)
C 1.20-1.30
Mn 0.40-0.60
Si 0.50
Cr 4.75-5.50
Ni 0.30
Mo 0.90-1.40
V 0.80-1.40
Cu 0.25
P 0.03
S 0.03

It also explains why 18650s have very good attraction to magnets as nickel and steel/iron are both the only common ferromagnetic metals that exist.

If they constructed 18650 cylinder cells out of copper people would easily be able to stand of them and squash them and possibly cause all sorts of interesting little fireworks displays, and more importantly law suits.

 

[riba2233]

I wouldn't say it's 50% nickel, it's just nickel coating. You can take an old 18650 cell and grind down the negative pole, and you'll see that the nickel coating is thin

 

[Cargobike]

Hello there, quite interested. Pm
Cheers

 

[ohzee]

This product is top notch and fwiw has my highest recommendation.

 

[riba2233]

This product is top notch and fwiw has my highest recommendation.

Thank you, that's really nice to hear!

 

[tomjasz]

Woohoo!
August 18, 2015 , 7:42 am
Departed USPS Facility
NEW YORK, NY 10199
Your item departed our USPS facility in NEW YORK, NY 10199 on August 18, 2015 at 7:42 am. The item is currently in transit to the destination.

 

[riba2233]

Yeah, NY is first station is USA You should have it in one or two days.

 

[tomjasz]

Yeah, NY is first station is USA You should have it in one or two days.

Out for delivery. Battery ready...not that I'm excited... :lol:

 

[tomjasz]

Build quality, EXCELLENT! The probes and foot switch absolutely blow the Sunkko versions out of the water. Amazingly fast shipping too! Well done my Croatian friend! Well done! Amazing how simple a good spot welder can be. Thanks to Kepler, MLT and others patience and now Jakov's welder I can repair and build my own packs. I wish I had found this welder before I wasted $250 on a Sunkko. BTW the Sunkko parts are for sale for the intrepid electronics savvy.

 

[riba2233]

Thanks, I'm glad you like it! I hope that the packaging did it's part fine and that it arrived safely and undamaged

 

[tomjasz]

Brilliant. I couldn't wait to clean the bench properly. The Sunnko welder is a complete PIA by comparison.

I had a marine battery 945 CA that is 4 years old and barely holds 13V. Leftover from a solar canoe adventure. Setting the welder up was also very simple.

WOW first past, first weld, clean and solid. Unbelievably simple compared to the Chinese cabinet unit. The weld tips are large compared to the Sunkko supplied. However that presents no problem. They are actually sized nicely for my size 8 hands. I will modify the cheap plastic jigs from Sunnko and also try the Sunkko tips, IF THAT DOESN'T affect the warranty?

Slightly longer leads for the weld tips could be handy. The supplied are certainly long enough. Once again comparing component quality, this difference is immediately apparent. I'll attach a photo comparison of parts later. Jakov has produced a simpler hobby kit. Finally a good welder for the soon to grow battery shop.

 

[riba2233]

That's great, I'm really glad you like it! Looks like your battery has swapped places for positive and negative electrodes, lol :lol:

 

[18650dude]

Does the polarity make a difference? Hate to blow mine up on the first try.