I actually had the carbon piles in this one glowing the other night in the shop.
It is a conversion of a Chicago Electric (HF) automotive battery load tester..
Mods include a range doubler for the volt meter so now it is 12v/32v. Amp meter at 500 amps was fine as was the shunt.
Added two parallel resistive loads for smaller batteries for lower current use and a toggle switch for them.
Added two fans for cooling. The old battery cables and clamps were removed for a setup that was better suited to model airplane use. After using it for a while I felt I needed some more resistance in the carbon pile so I bought a second one, took 3 or 4 discs from its carbon pile and added them to this one. Not necessary but it makes it easier to keep the pile pulling around 50 amps continuous. (Continuous for about 5 minutes). She does get hot!