The Unofficial Spot Weld Resistance testing and discussion thread. Making Samples phase.

[SternWake]

I’d like to apologize for not having done this sooner as I promised.

In the Spot Welding copper/ Copper sandwich thread we discussed this, and @Battery_Mooch had graciously offered to test some samples with precision equipment and the skills to use it properly, so that we could stop guessing.

Nelvick @DIY500AMP.COM has donated 21700 cell samples and I am here, tools in hand, some time, and am ready to weld some strips to some cells Would like to visit the post office By Saturday.

I am contemplating the best methods to minimize the variables, and allow for comparable consistency in the future, as I am not going to be able to cover every base.

I have an AwithZ P20B 14.6 KW spot welder, that has proven capable of welding 0.3mm copper under 0.2mm nickel plated steel, using Nelvick’s welding flux at near its full available power. I have solidly welded as much as 0.2mm+0.15mm copper under 0.1mm stainless using flux, but my machine was incapable of 0.2+0.2 under 0.1mm stainless using flux at max power. it was close, but not quite enough. 0.07mm stainless atop 2 layers of 0.2mm copper made no discernable difference.

In general I Use 0.2mm copper under 0.1mm stainless steel using flux below the copper, using gear 385 to achieve very solid welds.
Without the flux I need to use about gear 550

Without Flux or Stainless on top, to weld 0.2mm copper I need about gear 840.

Weld consistency fluctuates with no sandwich or Flux.

The amount of pressure, tip shape and cleanliness, and temperature of welder and Leads playing a much larger role when there is no sandwich and no flux, at least on my P20B welder.

I cannot ‘raw dog copper’ thicker than 0.2mm(0.25mm maybe?) and personally do not mind having to use stainless or the Flux.

I know @Pecos has a bunch of cell samples, An AwithZ p60f(29.4kw) , or is it P90C (56.8kw) spot welder?, and is willing to Weld thicker samples that I cannot.

I have 0.1, 0.15, 0.2mm thick, 10mm wide copper strips

I have 0.15mm thick 10mm wide pure nickel

I have 0.07mm thick 304 Stainless

I have 0.10mm thick 304 stainless

I have 0.5mm thick 16mm wide Stainless, some 400 magnetic series.

I have 0.2mm Nickel plated copper, which behaved exactly like Non plated copper in my experiments

I have plenty of Nelvick’s welding Flux and extra welding tips, and about 15 21700 cells. Some tabless and some not. Mostly virgin cells but a few that have little nubs of welded strips I will need to remove.

I know some have no interest in using either flux or Sandwich, and have machines powerful enough to be able too without, whereas my P20B can only raw dog 0.2mm copper at high power levels.

I think any thinner than 0.2mm copper by self, is just too weak on the tear off tests, that it greatly benefits strength wise from 0.1mm stainless on top.

I have welded sandwich using pure nickel, and nickel plated steel, but both of these require the use of lot more power than using stainless steel.

If going for copper sandwich I personally see no point in using Pure nickel or Nickel plated steel on top. They require significantly more power. I use neither as conductors, only welding aids.

I would like to find out the difference between 2 pairs of welds, and 3 pairs, and 4 as well.

I would like to find out the difference between welds with flux, and without flux.

Copper sandwich welds, and non sandwich raw dog copper only welds, both with and without flux.(0.2mm limited)

I’d also not like to overload Mooch with a giant box of samples to test, if consistency is poor and results conflict.

I am really pretty dialed in with 0.2mm copper on my machine and I know that’s where I will be able to deliver the most consistently prepared samples.

[fearlesstvn]

Really cool of you to take the time to improve things for the battery community.

I’ve already picked up a bunch of good tips from you just from reading your posts. Appreciate you putting in the work on this, bro!

[Battery_Mooch]

My votes are for only “worst” and “best” cases in regards to interconnect material, layer, and thicknesses. Then for each of those, minimum and maximum number of welds.

All the in-between setups don’t matter until we know if the range of power losses is wide enough (between best and worst) to make exploring those other configurations worthwhile.

[SternWake]

I was thinking in the interests of consistency and repeatability, using 25mm long 10mm wide strips.

CELL A is a virgin Ampace JP40 rewrap.

0.15 mm pure nickel.

2 pairs of welds on Anode -

3 pairs of weld on Cathode +

i used gear 90

0.05ms preheating

02ms ‘intermittent’ this is delay between preheating pulse and first weld pulse

Double pulse with a 0.2 second delay between weld pulses.

Gear 90(of 999).

Nothing written in stone yet.

Am more than willing to modify this baseline.

[Battery_Mooch]

@SternWake

CELL A is a virgin Ampace JP40 rewrap.

0.15 mm pure nickel.

2 pairs of welds on Anode -

3 pairs of weld on Cathode +

For “worst” I’d love see 0.15mm nickel with…

Cell A = 1pr welds on neg/pos

Cell B = 4pr welds on neg/pos.

Let”s see if weld count makes a difference with “low performancel interconnects.

Then two more cells with the thickest and highest layer count metal, one cell with one pair welds and another cell with four pair welds.

Then we can directly compare thin Ni/SS metal and thick Cu/Ni metal setups. We can also directly compare the effect of weld count on different metal/thickness/layer setups. And we only need four cells.

To be sure about reading and effect of weld consistency on the results I recommend 2-3 of each of the four cells listed above. IMO, consistency can have a huge effect but I have no idea if it’s true.

Other testing can include different weld “quality” on identical cell setups. That is, how much does an easily peeled off strip affect power loss? Must we always go for insane levels of “grip” and consistency? Or does any weld pretty much perform the same?

[SternWake]

I’ll do my best to get you exactly what you want.

So, cancel cell A. maybe I’ll include it and label it cell A-Z:

Cells A1, A2, and A3 will have 1 pair of welds on both anode and cathode, using 0.15mm nickel

Cell B1, B2, and B3 will have 4 pairs of welds both anode and cathode, using 0.15mm nickel.

That takes care of 6 cells.

0.15mm pure nickel being the ‘ worst’ available to me. Other than nickel plated steel or Stainless steel as a conductor.

The ‘Best’ conductor I have on hand is 0.2mm copper.

I can weld 0.2 copper both with AND without stainless steel on top.

I can weld this with or without Nelvick’s welding flux.

I think ‘Best’, with 0.2mm copper, would be 0.2mm copper under 0.1mm stainless using flux and 4 pairs of welds.

Spot welding Copper / Copper Nickel / Copper Stainless Steel Sandwich

I carefully filed the electrode that had can steel stuck to its tip, and made sure it was same size and shape as the other. Flipped a cell over in holder and tried welding the + tab with the same settings. no Flooux No preheating, triple pulse, 2ms interval Two very even, weak welds lifted off very easily. Tiny holes in copper, didnt bother with photo Tried again with gear 750, 1ms interval, triple pulse. [IMG_7588] Notice the steel colored ejecta on the weld on left. That is not a wei…

Scanning the other copper welding thread, in post 44, it seems I used gear 750 triple pulse to weld 0.2mm copper with no flux and no Sandwich on an 18650 cathode. The copper tore but I was unimpressed with the tear off strength. I don’t often use triple pulse. I have the most experience using 0.2mm copper under 0.1mm stainless using flux gear 385, double pulse.

How about the strip length, Should I stick to 25mm, or should I make it some set distance from the nearest weld/ or the perimeter of the cylinder?

I’ll hold off welding anything more, for now, as to best utilize the 10 virgin 21700’s I have left.

Will await your precise instructions :)

I can clean nubs from previously welded cells, but that adds an unknown variable.

[Battery_Mooch]

@SternWake

How about the strip length, Should I stick to 25mm, or should I make it some set distance from the nearest weld/ or the perimeter of the cylinder?

I’ll hold off welding anything more, for now, as to best utilize the 10 virgin 21700’s I have left.

Will await your precise instructions :)

I can clean nubs from previously welded cells, but that adds an unknown variable.

25mm from center of cell works fine IMO.

I’m just not able to dive into all the details of this. If the folks here just don’t care enough about the results to chime in with what results they’d like to see then I guess it just doesn’t matter what we do.

IMO, we can’t use previously welded cells for any of these tests. Well, unless we’re testing what results we get with previously welded cells. But then there can be a whole new set of conditions to test.

[SternWake]

Your recent test of the Vapcell / Ampace JP30p1 rewrap, with the button top adding so much resistance and wasting so much energy as heat, is at the core of my interest in this.

I don’t care that the extra temperature gain might not push battery or pack or conductors into the danger zone, I don’t want current heating conductors period. Screw resistance. Within reason of course.

I’ve been of the mindset that I want to use as thick of a conductor as my welder can weld at ~80% or less of its max power, and as many welds as I can fit on a 21700 cathode, which is 4 pairs.

I am of the opinion that only the welds themselves can be counted on to pass current, that the strip adjacent to the welds is rarely in direct contact. This should be a goal of testing in my opinion.

I think that the welding Flux actually tins the cell and copper immediately adjacent to the welds, increasing surface area in direct contact between strip and cell, further reducing resistance.

Maybe 3 pairs of flux’d welds equal same resistance as 4 pair of unflux’d.

This is a great opportunity to answer some questions.

My 0.5mm stainless experiment seemed to weld the fluxed copper below so fat so flat and so wide with just 1 pair of welds, and the tear off strength was so extremely high, I’d love to see if this is potentially lower resistance than a more sane sandwich.

I’m ready to weld and mail samples and get this started, I just want to make the best use of the Virgin cells I have on hand.