Is it not worth salvaging the PCB? Even if it’s only for testing? (The acid from the caps got every were still not got on rid of the smell even hit the ceiling)
On some step down buck converters you get a display with voltage and amp would be a nice little extra module you could develop in the K weld line later on.
Pressure on the probes makes a huge difference. Heavy pressure seems to make the welds weaker. Light pressure seems to make them stronger. This is worth experimenting/practicing with. I suppose I should add, keep the tips clean – something I too often neglect.
The negative herminal is the whole cell body, so can take a lot more heat. The positive terminal is a tiny piece of steel, and cannot dissipate as much heat. The terminals may also respond differently to the amount of energy.
After the claims of 175J earlier & just out of curiosity, I tried to pull 75J and released the white smoke from my 2 week old 4s lipo which now reads a few mA and us toast, alas nano-tech I knew thee barely.
There’s a reason most builders use 0.15 or 0.2mm strip - any thicker and you need a very short, high power welding pulse to get fusion, which these style of welders can’t provide. If you need the extra current carrying ability, I’d suggest doubling up on thinner strip rather than trying to weld armor plating to your cells.
I don’t think this is quite correct – the welder is providing the energy (granted it gets hot quick), but the amount of energy it takes to weld 0.30mm nickel seems beyond what’s healthy/safe for the cell and the process.
I do not think a stronger welder will make the 0.30mm process better. I wanted .30mm to work – stupidly I bought a 1kg roll of the stuff.
Sorry to pick at your post, but when I tested, I really did not like the adhesion I got with nickel to nickel welds. It seemed so weak and inconsistent even at high power. So me personally, I prefer one layer, and adding copper, or skipping right to soldering copper, if called for.
As stated in other threads I was using 2 turnagy grapine 6amp 3s in parallel
the battery’s were warming up but ok the xt90 was getting to hot that’s why I stoped and didn’t push the jules any higher. I think my weekest point seemed to be the XT90. If I remember right the battery’s are rated to 6amp *2 at 150c peak so 1800 amp but I’d expect that to be over ambitious as always with Lipo rating. The lith ion cells were getting to hot for my liking even tho these ones were cheep eBay crap I was going to throw away so I was pushing it higher than I would be comftable to weld a pack. I came to the conclusion that the .3mm nickel was too conductive and way to hot to touch after trying to weld and the only chance I had was to fined slotted stuff to aid the current passing in to the battry instead of along the nickel.
I was thinking of swoping the xt90 on the unit to XT150 and making a XT150 to dule XT90 but I don’t think that will be enough. I think the k Capps are the only real option that might work on .3 I could have a cold weld on my XT90 splitter as it’s with AWG8 cable that’s difficult to keep the heat in the cable as it wicks it away so quickly and is a little to large to fit in a XT90.
As fare as I’m aware a supposed peak manufacture rating of 1800 amps is one of the highest I’ve seen on esk8 forums and think this is why I’m seeing the XT90 issue that no one els is reporting.
I have been unsusefull in welding 0.3 mm nickle so fare but that doesn’t mean that this unit can’t do it. I have gone back to using 0.15mm to finish my current pack until I work out and refine how to use .3mm.
The issue I keep finding is people say it’s a power issue or the welders not powerful enough but thay have never used more powerful units and are just guessing.
Fact
I’m weld 0.15 sloted nickle consistently with jules as low as 6
I’m weld 0.15 nickle consistently with jules as low as 9
Iv tryed to weld 0.3 nickle with jules as high as 175 to a low standard at that point I’m having overheating problems of XT90, cooking the nickle and leaving to much heat in the cell.
That’s double the thickness at 20 times the energy I think that proves stronger power supply’s and heavy duty welders are not the answer on there own. I’m convinced 0.3mm nickle is to conductive to weld in the same way as 0.15. And if that’s not enough try sanwidging electrode craftblade 0.3mm nickle the electrode with a setting of 30+ jules then rip it apart
I try to pick up some more cheep battery’s so I can post the energy delivered in to the weld at them settings when I get home. Sloted 0.3 nickle will aid in the issues I’m having but I can’t fined any to try so fare if any one knows a place I could get some. 0.3mm nickle plated steel would have a higher resistance so wondering if that’s how people have welded 0.3mm in the past.
Reduced pressure as sergested by @deucesdown
Sloted 0.3mm nickle
Changing out XT90 to XT150 (to reduce resistance for higher amp delivery).
Super capacitors
Cleaning my welder tips again (thay were new replacement ones when I started playing with 0.3mm)
For me, IIRC, the order of things that get hot are:
probes OUCH OUCH 1 weld at 100j and it’s really hot
XT90
lipos where all the wires go in
lipo and probe wires
screw terminals
lipo cells
Remember kweld protects itself at 2000amp. You’re tickling that limit. Improving the connectors and wires might push you over.
@jeffwuneo I remember you mentioned you can do custom nickel? Would you be able to do something like 0.30mm thick, 25mm wide (double wide for foldover), 62mm long (span 4 cells), slotted over the cell contact points? Something like this?
Just doing some rough math. If 12s is most popular, 1000/12 is about 83 packs. $1500 / 83 packs = about $18 per pack, plus the cost of the nickel. Hmm…
Totally agree this is mental ampage and why I’m convinced more power is not the solution even tho that’s what people keep saying.
I thought a XT90 was more than enough couldn’t believe how hot it got after 4 welds so I don’t think swoping that to a XT150 is a bad thing.
Yes the limit is 2000 amps and why I really don’t want to add a 3rd battery in ther as spec wise I’d be up to
18ah 3s 150c burst is 2700 amps
taking in to consideration the over speck of LIPOS I believe this could deliver the 2000 amp limit of the system and probably brake some thing.
Love that design iv seen some tabs have dents for the probes to sit when welding would this help? and the other think I’m thinking is there a way to make it better for soldering on at the top would some pin holes help or hinder when soldering?
@jeffwuneo
interested in buying .3mm Nickle shapes for testing what options do you have that might work?
That’s not worth the effort, and I have enough stuff for testing here. You can discard that module.
A next gen kWeld will certainly have a more versatile dot matrix display, and that allows doing this with ease.
I would guess that this causes arcing, and it the produced ionized gas is very hot. But I wouldn’t recommend doing this, as this will likely have a negative impact on the repeatability.
That’s a way too low number, what exact battery model do you have? Is it the recommended 6000mAH / 3S / 65C Graphene pack? That should deliver at least 1300A, better 1400A. Also, do you use the stock kWeld cabling and no other connectors except an XT150 or XT90?
These deliver 1100 to 1200A and won’t allow 0.3mm nickel. I had tested putting two of them in parallel, and that cranks up current to 1700A but that might be a last resort as that would also be very pricey.
I’d say 0.3mm is the limit of kWeld but only if you have a power source that delivers enough current. It is all about the combined electrical resistance of the entire system. These type of welders basically short circuit a battery, and getting a large current requires getting all the resistances as low as possible (while not exceeding the 2000A limit of the module):
battery internal resistance: use high discharge models and add capacity in case
battery wires: the standard 10AWG is a bottleneck, and I had asked manufacutrers in the past to sell me 8AWG+XT150 models but no response from them. Shorten the cable if possible
battery connector: XT150 is a good compromise between cost and resistance, but there are some other gold bullet systems that are even better
The problem is that with nickel strips of this thickness it is even more important to keep the welding pulse as short as possible, 50ms at most is desirable. The longer the pulse gets the more heat can spread out, which can eventually damage the cell internals. It’s both my own experience and feedback from others, that 0.2mm is the better choice in most cases. Unless using very large Li cells (that often come with screw posts instead anyway), the current that you can draw form a single cell is normally less than the 20A that these strips can safely carry anyway. In many cases you do something like this: weld a thin nickel strip across all the parallel contacts (which will then carry balancing current only), and then weld a large number of wide and short connecting strips next to each other to put them in series. The two output terminals then can receive a heavy gauge cable that is soldered to each individual column of the pack.
Agree to that, this requires changing the method, and AFAIK the industry uses laser welding for e.g. copper to battery.
even hit the ceiling)
I was thinking the total opposite I was applying more and more pressure trying to get the current to go down in to the cell thanks need to try this.
