yeah i saw that one but then the small print at the end
Buyer will need to source:- 6 or 8 power MOSFETs, gate resistors, single sided copper clad board for power module. One Schottky diode One TVS diode Weld cable - 25mm sq minimum recommended Copper wire for electrodes - 5mm recommended, soldered to ends of weld cable. 12 V dc mains power adapter. Footswitch - normally open.
I’m actually working on building my own spot welder with super capacitors. Right now it kinda works, pretty badly lol, but it does. All I’m using are 4x 500F 2.7V caps in a 2S2P config for a total of 5.4V at 500F and I just soldered two “electrodes” to the terminals, which are just really thick solid copper wire. Then I just press them both against a battery tab on a 18650 for half a second, and it works. Now obviously this isn’t a long term solution because it has a lot of problems, though it did only cost me around $15 to do.
Super Capacitors Link: http://www.ebay.com/itm/291969748080
I’m planning on setting up a Arduino controlled MOSFET switch with a foot pedal for doing it in the future. I’m planning on using IRLB3034 FET’s because 1, I already have some 2, they have a gate-to-source turn on of only 4.5V so I can use them with low voltage cap banks and with logic level voltages (5V) and 3, there relatively cheap.
IMUO providing that amps to spot weld nickle isn’t the hard part, control is the problem. Ideally a double pulse of a controlled duration is desired from what I have read
Yeah I can see were thats true because you can just pickup a car battery and do it pretty easily, but I wanted to do it with super capacitors mainly because I didn’t have a spare car battery laying around, and also I really like these caps lol. I’m still going to see about designing a control circuit maybe with a little 16x2 LCD display and a couple knobs for controlling pulse length and what not. Main problem I’m having right now is deciding whether or not I should use a MOSFET gate driver, and if so which fricking one!
esk8 is just a dilemma from start to finish sometimes lol
Getting a car battery is easy or you can just use two 3S lipo’s in series. Though I’d not trust using Lipo just because of the fire hazard.
I actually put serious thought into buy a Chinese spot welder for about 125 then flogging it on when I’m done and just swallow the loss as the cost of doing the job. I’ve tried finding a second hand one and they’re as rare as rockinghorse dodee so I think would sell for good price.
Same but they use high voltage so you need a leakage breaker I think. Not something that is installed into every home. Also those cheap china ones only weld max 0.15mm nickle strips when you really want to be using 0.3mm. You need to spend at least £200 I think. Or you have to double up on the nickle strips but that is more work.
I contacted the seller of the Ardunio kit and he expects the PCB’s to clear customs any minute now and should have the pre-built kits available to buy over the weekend. The other bits I can pick up with ease in a few days and then i can test it on some old 18650’s I have knocking about
Coolio let’s meet know how you progress, if it goes well in test, will have to sort something out with you. Going to have to find a good deal on batteries and BMS shipped to uk.
Well let me know about the BMS as I need to source one. I’m also going to need a charger and figure out how it all works
I bought my batteries from Amazon for £3.90 each delivered (I have amazon prime so no shipping fees). Just order them in pairs as that is the cheapest option. I looked everywhere and that worked out the cheapest and fastest. Also no tax or duties to pay either.
I’ll do that. Soon as I get an hour on the pc I will get my geek on 
Hey guys,
If you wanna build one feel free to check out my build thread. 
Hey @Jack, I saw your instructable and it seemed very interesting! I have a couple microwaves I’m waiting take apart, so I might use a transformer for doing it.
Also another option would be using a real spot welder which you can get on eBay for around $60. Here’s a link of one I found, http://www.ebay.com/itm/131610715017
That is not a spot welder 
Oh yeah your right lol. Well you get the jist, and it would still work if you used it like one.
Thanks for that… I’ll look into getting the BMS when I get paid.
Good news, the spot welder just turned up and the guy even soldered and supplied the wire and welding tips! So all I need is a PSU, car battery and foot switch. Happy days
PSU? You can hook the arduino to the 12V car battery
Reading the instuctions they say to use a separate PSU to power the arduino. Probably to protect the chips when the battery shorts.