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Boss level custom spot welder


You mean those? 70a is very good. You will need a 3s5p though. Really expensive. I recommend you a lead battery like the one that Kevin said.


You average Lipo outputs less than those A123 cells.
Stating he needs 5P is based on which measurements exactly?
What lipo do you use? The 20C or 30C Turnigy at 5Ah would theoretically output up to 150A (which is exaggerated by the manufacturer) so a 2P would already be in that ballpark.

None of us has ever measured the current an 18650 outputs for such a low duration as well. The rated currents are meant at constant discharge until the battery is empty - this is a totally different scenario.
I would love to see some actual measurements on what current the cells output when shorted - there must be differences but no idea how much.


The lipo “burst” output is what matters. There is no need to even look at the continuous amps rate. My lipo delivers 350 amps. Lower quality lipos work too but the better the lipo the better the performance.


How did you measure that? I’d like to do that with my batteries as well

Also you were the one looking at the continous rate and recommending a 5P pack.


Mwahaha will you deny everything I say?


I honestly wanna know - you can’t just use a multimeter to measure such a current - especially at that short duration so you need some other tool.
Finding out what batteries work well for a spot welder application could be really helpful.

You also seem to forget that my initial assumption was right so why should I be a troll?
I am naturally suspicious of any claims that have no proof - that comes with the territory of this forum where a lot of products did not live up to their claims.
Don’t take this personal!

I am glad we found out about the spot welder’s timing function - personally I walked away smarter than before as I now know that apparently Lipos can handle the abuse.


Zippy lipos have been reported to have exaggerated continuous C.
Nanotech have been reported as legit Therefore I never had and never will measure it myself. My time is not no waste. When I see a chocolate bar “300 kcal” I guess it is right. If not …who cares? I will not measure it.


You say in two subsequent sentences that you can’t trust labels and that you trust them?
I care as this is a crucial information that might cost people money when they build 5P instead of just 2P packs.


…said the guy who is not a troll…


According to A123’s spec sheet of their 26650M1B’s, the burst discharge rate is 120A. Continuous is actually closer to 50A. And yes, I’m fully aware they are way more expensive than just going the lipos route, but I just want to know if it’s a possibility for me and others if it works as an alternative.

And if I’m reading this right, you said burst discharge current is the one to keep an eye on…so when looking at the lipos @aulakiria recommends on his blog, the burst C on those is 50C…so multiplying the capacity by the burst C, it comes out to a theoretical 250A (hopefully I did this right). So if this is right…the minimum A123 26650M1B battery pack size needed would be 3s2p, but 3s3p would be much better.


Low parallel packs are not a good idea. I guess 3p is the minimum you should use in case the burst they claim they have is true. I used some lifepo4 packs many years ago,before I started using lipo. The discharge rates continuous were right. The burst were not…
Nevertheless a123 has a huge reputation, it is probably true.
Maybe some people here has real life xp with Those cells and can give you a good advice.
I balance my lipos often and care for them properly. I store them inside fireproof bags and I do not fear them at all. With proper use they are not the end of the world.
Use what you think suits you best. Ask for more opinions and I hope you find a good solution.


The more in parallel the better - the burst current when shorted is hard to tell and we don’t really know.
A123 are one of the highest discharge cells you can buy though so you should be fine.
You could also look into larger cells if you don’t care about the size or weight.
There are 38120 cells out there as well.


Thanks to both of you. I’ll do more research on the batteries, since I know it’s possible to use them.


The purpose of this thread is sharing experiences with this welder.
In case you end up buying it and using a non lipo solution please share it with us.


I love this welder! I was going to buy a chinese battery but I think I will think it twice.
Thanks for sharing this info.


Welcome rashid :blush:


Just got the welder. Nice!

Thanks @aulakiria for letting me buy one (and for reverse polarity protection!). Thanks @rojitor for all the testimonials and videos. Thanks @Maxid for keeping everyone honest.

The soldering iron, I don’t think anyone noted. I think it’s a clone of the Hakko FX-951 system’s handpiece. That’s a $300 system. When you get past the Hakko 888 level, these temperature controlled tip based systems have amazing thermal recovery and they tend to have nice small handpieces. REALLY nice for $15 add on, and with a nice big fat chisel tip, would be awesome for portable eskate repairs/mods.

Aaaand, I have some new loose A123 cells and a new spot welder. For science? j/k I can’t afford to burn 3 cells out of my spare set of 12… So hard to replace!

EDIT A123 are 3.3 nominal 3.6 max, so 4s


I bought a few tips of Digikey T15 model (about 15$ CAD a piece) and omg they heat up sooooo quick! About 1-2 seconds to reach 300 degrees!


it’s amazing using the larger tips on things like XT150 and 10awg wire


@aulakiria Props yo

Just finished mashing my 4p packs up into the snot of my bench model.
Now I know why gadgets like these are a gem.