Kweld spot welder

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@Darkie02

Just put the XT150 wire AWG10 cables on with a lot of difficulty tho this haven’t done any were near as much as I hoped to reduce resistance.

Why don’t you just solder the two male XT90’s right to the input of the welder? You could eliminate the XT150 and additional wiring entirely, and still have a system with detachable batteries. What is that black thing left to the upper XT150 in the pictures? Just a sleeve, right?

@Darkie02

I thort that but this was what the designer of the weld caps said

Yes, based on my tests here. I had been using solid strips of pure 0.3mm nickel, and it doesn’t weld that reliably here. It depends on what you actually use - Hilumin (nickel plated steel) welds significantly easier, and slotted strips help guiding the current and also improve the situation.

@Darkie02

As fare as I understand using higer s count battery’s hinders more than helps any thing over 8v needs to be disapated as heat so it’s better to use 3s than a 4s

It’s really just Ohm’s law. Desired current is 1500A. The resistance of the kWeld system is roughly 3.2 milliOhms (stock cables). The weld spot itself contributes another 1 milliOhm typical. This gives 4.2 milliOhms total. To push 1500A through that, you need U = R*I = 6.3V from an ideal battery. For every milliOhm of battery’s internal resistance, you need another 1.5V accordingly. Or in other words, for every volt above 6.3V that the battery has, it needs to have 1 milliOhm of internal resistance to stay in the sweet spot for the current. A 3S battery therefore needs to have 12-6.3 = 5.7 mOhms. Then calculate the power loss in the battery: P = 0.5 * R * I^2 = 6412 W. That explains why they heat up quickly, even though the pulses are short. Now consider a 6S battery. That must have an internal resistance of 24-6.3 = 17.7 mOhms. Then P = 19912W. You see that the power loss in that battery is huge. This is why I recommend 2S to 3S batteries for the welder.

@Darkie02

I gained 20 amps by pushing the tips like this in stead of pushing the points together like I did before thought it make a bigger difrence.

Having the sides touch instead of the tips gives you an incorrect calibration result. It is very importan to have the tips touch correctly (pushing the conical areas is okay). Make sure you get no sparks, otherwise repeat. This is important for the energy metering to work properly.

@Darkie02

Iv been unable to get it to weld 0.3 nickel strip consistently and I think it’s more to do with the lack of resistance in 0.3 nickel than it is the welder.

That should definitely be possible without problems, especially because you are running the welder at higher amperage than I do here, and it works well here. The result also depends on the type and thickness of the battery can itself, is it possible that your batteries have aluminium cans? kWeld can definitely not weld nickel strips to that material.

Another important advice (sorry the user manual lacks this info): kWeld does not like voltage applied to its electrodes; this can happen when accidentally touching different poles of your (large) battery under construction. Please be careful to avoid that, otherwise you may kill the unit.

@Darkie02

Frank can you PM me you address to send the Ksupply back for repair please.

That’s public on the website:
keenlab UG
Langestrasse 9
26388 Wilhelmshaven
Germany

@Darkie02

Just a quick reminder I’m not nocking the unit I prefer it to others. I’m trying to do things with it that can’t even be try with other diy welders.

Much appreciated from my side!

@Darkie02

Would you recommend people useing 0.3mm strip with the Kweld. No

If you have, please make tests with slotted strips. You should get better results with that. Nevertheless, I share your opinion that welding overly thick strips to your battery requires a lot of heat that can potentially damage the cell internals. What happens to the back of your blade also happens to the battery. When a customer asks me, then my recommendtion always is to rethink the solution and check if thinner material might be the better option.

@Darkie02

high amps delivery is what I thought makes the weld.

Exactly. These are officially called “resistance spot welders”, as the operating principle is to push current through the electrical resistance of the material to weld.

@magharees

the voltage ‘punch’ of 4s

It’s voltage that causes current, and it’s current that causes heat. So the right term would be ‘current’ punch. I hope that I could clear up that relationship in my above calculations

@Darkie02

Starts ripping holes in the Nickle when pulled of with pliers at 6j but only on 1 terminal constantly, 8j rips a hole in the Nickle on both contacts for me

That’s a clear sign of bad calibration, please repeat that and check. 8J barely be enough to weld 0.1mm nickel.

@Darkie02

I think amp delivery has a large diffrance in the 1200-1800amps

The joule metering algorithm automatically adapts to varying situations (battery voltage, current, corrosion,…) A higher current allows to weld thicker material, and it keeps the pulse duration shorter. The latter is desirable as it avoids heat spreading out during the pulse. That causes some variation, and is generally good to experiment to find the correct setting before making large batteries. Do this for each type of connection: strip to negative, strip to positive, strip to strip. Different types of batteries again can require varying this, because they may have cans of different thickness for example.

@Darkie02

A higher supply deliveres the energy in a shorter amount of time resulting in more consultant welds and less heat spreading out over a wider Area. The question is when dose diminishing gains happen.

@Darkie02

It’s a much larger difference than I would have expected but is this to do with the curve or is there other factors to consider more pressure cleaner tips lower resistance of build.

It’s important to get as little arcing as possible, hence push hard and work with clean surfaces where possible.