Hi All
This is a DC welding machine i built to do racking repairs in large warehouses. The power supply were forklift batterys depending on the batterys available i set the welder to 24 vdc, 36 vdc, 48 vdc The reason i built this is as follows. In the large WH Theirs is no AC near by and if there is power the fork lifts moving product would run over any cables also in many cases i could not run engines inside the building. So i had a challenge I decided to start with a 150 amp dc battery charger. I removed the controls ac cooling fan. left the step down transformer the load resisters and added 2 more load resisters a 200 amp .5 ohm.
i installed 3 battery sb plugs 24 v 36 v 48 v each one was connected + to the transformer secondary coil. This acted as a choke ie resister. next to a 500 amp contractor with a 24 vdc coil. . This controlled the power to the stick. control wire was run down the whip to handle. After the contractor there were 3 welding cable twist lock plugs. first plug had large double resister second had one resister and third had no resister. The neg power was run from SB plugs to neg twist lock on front of welder. I installed a 24 vdc fan for cooling The 24 vac components had resisters to reduce voltage from the other battery voltages. I know you're wondering if car batterys would work. Yes they will. BUT the design of the internal parts of a car or light truck battery are light and this will be hard on the plates and links inside. and deep cycle are more delicate. I used old led acid i cant say if the new agm and lithium could withstand the load.
any way for you off girders that need to do a bit of welding this is a basic design that may be use full.
fyi this welder made the smoothest welds ever pure dc is vary nice.
