I need a large 12V load...

[JWLV]

63A x 10 = 630A @ 12V = ~7500W
Wow! Make sure to wear your protective gear when you do the testing.

 

[zgk51]

You don't need all these fancy resistors. I was stuck on this same problem a few months ago, looking up all sorts of 12v water heater elements... eventually made a perfect load resistor in 5mins out of steel wire wrapped around a plank of wood and then submerged in a bucket of water!
It was a good ~20amp load for testing my 24v batteries. I then made a second one and connected them in parallel to get more load. Worked well. I ran them for about 16hrs with a victron smart shunt to log the current over time.
I used cheap zinc plated tie wire, perhaps about 0.5mm thick, and about 5m of it wrapped around a wooden plank. I'll try to find a pic...

Ps. I realise the OP is looking for much more power but my point is long lengths of steel wire is resistive enough and the water keeps it cool enough that it won't burn out. I think you could make something similar to mine but with a much higher power.

 

[seneysolar]

Nobody wanted to recommend the 10k inverter?

 

[Warpspeed]

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[Warpspeed]

A 1Kw electric radiator bar of similar size glows bright red hot.
Those resistors will work fine, but not at 1Kw each.
Prepare for much initial smoke and smell.
Once they turn black they will be fine.

Suggest you try two in series across 12v.
12v at 32A = 384 watts or 192 watts per resistor.
At that estimated temperature rise, you should just be starting to get into the hot smell region, but no smoke. They will still go black over time.
Ten of those maybe 1.9Kw 160 amps, and no drama.