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Recommended cheap lipo(?) pack(s) for spot welder

Hi folks I’ve got this cheap ass spot welder coming to me:

Some say it will commit suicide right away. Others say it typically only pops if you are underpowering it, that the mosfets need full amps to work.
So my question would be: what cheap battery would people suggest to drive this.
(I only need it to weld a dozen replacement cells in my old Boosted - not looking to build packs at least right now - so minimum cost that does the job is what I’m looking for)
I could also get a car battery if people think that’s best but I don’t own a car so I’d prefer not to drag a car battery around for the rest of my life.

Instructions for battery:

According to actual test, welding 0.1 to 0.12mm thickness of nickel-plated steel strip requires a working current of 120 to 180A. If the battery cannot output current in this range, the welding will fail.

Recommended battery capacity:

1: 12V car battery from 25 to 40ah, requires good performance and small internal resistance

2: 4000 to 6000mAh 45C to 60C 3S aircraft model lithium battery

3:30 to 35ah 12V capacity lithium battery pack

Alternately I have 48 A123 26650s and only need 12 for my boosted. It does seem like I could put 24 of them in a 12s2p and in theory it would have more than enough pulsed capacity to power the welder:
edit that’s not right it should be 3 or 4p since the welder wants 12V

Max Continuous Discharage: 50 A
Max Pulse Discharge Current >50% SOC (10s): 120 A

I kinda like this solution but then my problem becomes how to build the pack the welder needs.
Chicken and egg.

Cheapest way is probably a car battery, but even that will be more expensive than the welder and its unlikely you can make a safe esk8 pack using nickle thin enough that this thing can weld it

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The product description shows maximum of 0.15 nickle coated steel. Out of a 30mm wide strip, that is only like 12 amps. You can probably find people using it for like powerwalls but for esk8 this isn’t suitable