So I've been looking to make a spot welder for an 18650 battery pack. I found a few videos of people using lead acid car batteries with a solenoid relay to put out quick bursts of energy (such as this: https://www.youtube.com/watch?v=o4NaDMoEHxU). I wanted to follow this but I can't find any cheap car batteries with high current capabilities nearby. So I found these high discharge lithium ion polymer batteries (https://www.ebay.com/itm/4-SPIM08HP...h=item2a9dd7b58d:g:mskAAOSwhfdaakSO:rk:3:pf:0) that can put out 200 A continuous that I would like to use as a high current source. Seems good to me. What do the experts think?
I’M NOT Spot Welding Using Lipo
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eee291
100 kW
It's not about the cont. current capabilities. A 75Ah 400A starting current battery is enough to put out 2000A for a few milliseconds.
Also, you might want a more professional welder instead of a solenoid.
https://malectrics.eu/product/diy-arduino-battery-spot-welder-kit-v3-2-2-full_bundle_car_battery/
Also, you might want a more professional welder instead of a solenoid.
https://malectrics.eu/product/diy-arduino-battery-spot-welder-kit-v3-2-2-full_bundle_car_battery/
Ok thanks, I like that Arduino idea. Looks like a fun project. I’ll probably use my own microcomputer to drive a solenoid relay for a set number of seconds. Or maybe driving mosfets is better? I will have to keep researching.eee291 said:
Also, I understand that the constant current capabilities aren’t the burst capabilities, but they are usually related. So this Lipo looks pretty good to me. It is the explodey kind, but I honestly can’t find any car batteries used or new near me and the lipos are so cheap at $40.
I use some graphene Turnigy 3s packs with my welder and they work great. 2k amps measured.
Way smaller than a car battery.
Way smaller than a car battery.
j bjork
100 kW
I have built a welder like that, using a car battery and a solenoid. I was not satisfied with te resault, some welds were good. But some were not. I was able to pull off some of the welds, and if i did not make enough contact it would burn holes in the nickel strips. I ended up soldering instead. It may have worked just fine, but it did not feel secure.
j bjork
100 kW
I used solid copper wire and 60/40 solder that flows easy. And some (I don´t really know the name in english) solderfluid? To make the solder "grip" easy.
Soldering flux.j bjork said:
Ok guys, I went with a car battery because I don’t want to burn down my place. I bought it from Walmart online for 34$ shipped. It’s a 12V SLA with 210CCA; my fingers are crossed, hoping it is enough. I bought 4 of these (https://www.arrow.com/en/products/psmn2r0-30pl127/nexperia) logic level mosfets that I will drive with my Arduino that I had laying around (apparently arrow has FREE OVERNIGHT SHIPPING with no MOQ which is pretty sick). Bought 2 bus bars for drain and source. Bought 2 feet 4 gauge and lugs. Now we wait for the stuff to arrive.
I hope the FETs are strong enough to withstand the current. It seems like they are pretty good based on the spec sheet, with 100 A continuous current and low open resistance (2.3 mOhms) I hope my Arduino will have no issue switching them quickly for pulse welds.
I hope the FETs are strong enough to withstand the current. It seems like they are pretty good based on the spec sheet, with 100 A continuous current and low open resistance (2.3 mOhms) I hope my Arduino will have no issue switching them quickly for pulse welds.
Got the car battery. https://www.walmart.com/ip/YTZ12S-12V-11Ah-Battery-Replacement-for-Yamaha-FZS1000-FZ1-VMAX/656509490
It puts out over 600 amps according to my clamp meter. I’m just doing dead shorts with no switch, and I’m afraid it’s almost too powerful. Hopefully it will play well with my Arduino and mosfets.
It puts out over 600 amps according to my clamp meter. I’m just doing dead shorts with no switch, and I’m afraid it’s almost too powerful. Hopefully it will play well with my Arduino and mosfets.
shortcircuit911
1 kW
I'm literally doing the exact same thing. I've ordered a solenoid and copper nails, etc to make a cheap spot welder. I remember seeing some good/inexpensive batteries like the one above at Walmart- going to pick one up soon. I thought about the malectrics one as well and may still get it, but I'm on a budget at the moment so I'm going to try the cheap diy method to get me going. Good luck!
shortcircuit911 said:
Mine seems to work great! Running it off an Arduino powered board and I can weld with a few milliseconds of current. I was initially looking at the solenoid circuit, but now I’d definitely recommend the mosfet approach, as it allows you to control the current pulse precisely. Also, I was afraid that my battery (rated for 210 CCA wouldn’t be enough), but it definitely can blow a hole in the nickel strips if left on long enough. The 4 parallel mosfets also seem to be the perfect fit! It still needs some tinkering with the timings and electrodes but I’d say my build was a success.
Good luck to you as well!
RichW_SC
10 mW
shortcircuit911 said:
I also tried rigging up the battery - solenoid - momentary switch - copper nail setup (exactly like the youtube vid)... It just caused a huge burn in the top of my test battery. Totally fried it, nearly caught on fire. Never was able to get a decent reproducible weld. There is no way to control the current thru the weld and no way I was gonna use this on $250 worth of 30Q's.
Ended up ordering a malectronic ardruino kit.... Hope that works better, get it tomorrow.
Hwy89
10 kW
I got the last Jp welder from Riba before he got sick. Works great thousands of welds later. He is back and selling welders again. Save yourself some headaches and just buy the JP spot welder.
shortcircuit911
1 kW
I'm all for the malectrics or even the JP welder, but it's not in this months budget (EEB project is bleeding me dry). The way I look at it is this; the malectrics needs a 12v battery (or lipo)anyway to run so I'll get that and see if adding a timer, solenoid, and foot switch ($20 in parts) will result in a decent spot welder to get me going. If it sucks I'll ask santa for a malectrics welder.
