Found it fun and did the math:
From the post below:
135A * 28V = 3780Watt
3780 * 5% = 189 Watt per hour, but 135A & 28 V needed too.
Googling, i found that AA batteries (who should give 1.5V) are rated for 2.4 amp-hours, so at nominal discharge rate they should give 2.4*1.5 = 3.6 Wh
To get the voltage, you’d need 28/1.5= ~19 batteries so you need 19 AA batteries in series.
To get the amperage, you’d need 135/2.4 = ~57 batteries in parallel. You can exceed the nominal 2.4A but then you run the risk of batteries overheating and exploding, plus this is detrimental to their storage capacity.
So a great big array of 57 parallel lines each consisting of 19 batteries is required to power the 135A/28V welder. This means 1083 batteries. Much more than 70.
If someone is able to wire them all together (not exceedingly hard, but should last a while - eg. using a soldering tool you should be able to wire two batteries in about 5’, so 1083*5’ = 5415’ or 90.25hours. So assuming 8 hour sessions (any more and you’ll start making mistakes), this translates into ~11.2 days of work)
After investing so much time, you’d get 1083*3.6=3.8988 kWh of stored power, which translates into 3898.8/189 = ~20.6 hours of use.
If you made sure to make this into a permanent array (and you really should if you go that far - maybe use a large wooden frame and create the grid on top of it, securing each battery in position) and also used rechargeable batteries, it would be possible with a little more knowledge to be able to recharge this contraption in place.
TD;DR
As Greiger said, its NOT easy to power a welder with AA batteries. But it is not theoretically hard to do, only time consuming and involved. We could create a recipe taking 1083 batteries and 90 hours (possibly in intermediate 10 hour steps to create a half built product), requiring mech skill ~4 and fab skill ~6 to create a ‘portable welder power supply’.
Is it worth it though? To the person in need certainly, but i personally would try to scavenge the oxy-fuel powered variant or use a car battery to power it (or install it on a car)
PS. I also ran the numbers for the size of the grid. With 50.5mm x 14.5mm batteries, plus 20mm gaps in between, it amounts to ~1.5 x 2 meters.
