Finished UK Efoil build

Spot welder woes!

I finally got all the bits to build my new battery pack but after digging out my diy spot welder I realised its not man enough to spot weld 0.2mm nickel.

Any recommendations for a suitable spot welder?

I know about kweld but it’s very expensive. I came across items like this on ebay but I’ve not had any experience with them

https://www.ebay.co.uk/itm/314433898225?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=t8099o7eq_2&sssrc=2349624&ssuid=3K6aTunkQlu&var=613022002988&widget_ver=artemis&media=EMAIL

Malectrics spot welder or KWeld. Both will weld 0.2mm nickel.

Just some feedback on the cheap ebay 99 gears spot welder.

It blew up!

It’s was OK for thin 0.1mm nickel but soon as I gave it a bigger 12v battery power source and tried to weld 0.2mm nickel the FETs popped.

I use a malectrics and it works well.

This does get complicated!

Malectrics have a min order value of 160euro to the uk, so I can’t really order it.

Kweld has a uk supplier and I can get it for £175 but I was hesitant because of the price and an email I recieved back from them kind of saying a car battery might not give good results.

“Generally it can work with kWeld but isn’t providing good results with such a material (from what I see from our users) it can go up to 1200 amps but not more.”

This was from me asking about welding 0.2mm nickel.

But when I have searched this forum people are just removing there car battery, happily welding their packs together and sticking the car battery back on the car!

I used the cheap red spot welder from AliExpress, and modified it by following a YouTube video to add an additional resistor. I used an old car battery and took my current car battery out, put them in parallel.

Seemed to get reasonable welds with a copper nickel sandwich (0.1mm copper 0.1mm nickel plated steel strip)

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Old debate, spot welding or soldering, here is a short about how to solder not only 0.2 or even thicker nickel strips with pre-separate (=minimum) heating for cells and strip. For cheap.

Channels to watch:

[Off Topic by ErCanEverything] For the Parkside fans out there, the 220V 1180Wh portable power station

After blowing up the cheap chineese 99 gears spot welder I decided to buy two more :thinking:

There is a good reason behind the madness, the circuit board actually has 5 more positions ready to solder on more FETS, the second circuit board was the donor.

I added loads more solder to the tracks and shortened the cables, now when connected to my 110ah 12v leasure battery it welds 0.2mm nickel @30ms



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The 0.2mm nickel strips have been formed with a 3d printed form as others have done.

The modified cheap Chinese 99 gears spot welder performed well


Because the spot welder isn’t as advanced as Kweld etc I did everything I could to give it a good chance, practicing on old cells to work out the best ms and car battery voltage, I also degreased the nickel strips and battery terminals. If the car battery voltage dropped by half a volt then I would charge it back to the testing range.

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A bit closer





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I’m finding it very difficult to solder 6awg wires to QS8 connectors, I have destroyed a few already!

You need a monster soldering iron. I run either a 200w iron or use a butane torch to solder 6awg

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Hello, Gazman79.
Using a 8AWG wire would be a certain death for your pack or you made it with 6AWG just for sure?
Thank you.

It’s going to be a dual purpose pack, 8AWG would be fine for my efoil but I intend to use the battery for an electric paramotor as well.

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Pack finished :slight_smile: no BMS it will be balance charged from RC charger, it does have ISDT Battair bluetooth modules on board for general voltage checking.


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Efoil build V1.5

Instead of building a brand new V2 Efoil I decided to modify my existing board into a more user friendy setup.

The main differences include cutting the board down from 155cm to 135cm as the back end was quite long, adding a proper hinged hatch and ditching the round screw on hatches and bolted main hatch. I also transferred the motor from the Gong V1 mast to the Gong V2 mast and made it more streamlined.

Motor - Flipsky 65161 120kv
Battery - Molicel P42 12s8p 33ah
Hydrofoil- Gong Curve MT 80cm mast
ESC - Castle creations HV160

You can see the original board at the beginning of this thread, but here are the finished V1.5 pics.





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More build pics.







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That looks really sweet. Can you show in more detail the motor mount and fairing?

I would love to but i lost a bunch of pictures when i moved data to a new phone. I basically did the same as a few others have done and cut a notch out of the mast and bolted an aluminium disc into the mast using 3 x m5 bolts, I also used a methyl methacrylate epoxy to stick it it place with a fillet just to make sure it was strong.

This is the best pic I have left, but already shown above.

great setup, trying to avoid the BMS as well. which (waterproof?) connector did you use for the balance wires - both on the box and for the balance charger?