Hi - I'm working on an active load for testing high power batteries. My goal is to be able to load it with about 75A. The power dissipation is not a problem. However, I'm realizing that the current, well, is... I had originally planned on running the current through a PCB to a MOSFET mounted on a mega heatsink. But I think I'm going to melt the PCB unless I get a fancy PCB with really thick copper. So I think I should run all high current through discrete wires. At 75A, according to my reference materials, I'm going to see about a 110 degree C temperature rise in 10 AWG wires. Ouch! But maybe this is just fine? I mean, that isn't going to be damaging anything. Sure it it is power loss - but the thing is designed to be a load. So who cares.
I need to have a sort of H bridge carrying this current. I guess I can just solder big fat 8 or 10 AWG wires to gigantic MOSFETs (probably TO-247s), and though the MOSFETs will heat up just from the wires heating up, I think I should be fine, as they are designed to operate at up to 175 C. Wires will have rubber or Teflon insulation so that they can handle the heat. I should also note that this load will run for hours at a time - so it really needs to be able to take the heat! Oh, I should mention that there will be fans running on this system at all times.
Does this make sense at all? Anybody have any words of wisdom for dealing with this much current? Thanks!