Trimetric shunt/wire size question

Empty Nest, Soon wrote:
Grizzzman – My concern was at what point does the cross-sectional area of the conductor (the bracket) become small enough that it gets hot from resistance and perhaps burns in two? Same principle as a fuse.

But, I suppose if the voltage drop across it is so negligible, then the heat generated from the current passing through will also be negligible?

Wayne

The heat generated is, for all practical purposes, the power dissipated by the connection--after all, the power has to go somewhere, and heat is the only real option. Thus, it's proportional to the current multiplied by the voltage drop. .01 V drop at 100A gives you 1W of power. You're well under that, of course, both in terms of current and voltage drop. (Note that, since the voltage drop is proportional to the current, the power dissipation is proportional to the square of the current. That doesn't really matter here; we're way far below any danger.)

How hot the connection gets in terms of temperature depends on the heat generated and the rate at which heat is dissipated to the rest of the world. As it gets hotter, the rate of dissipation in absolute terms goes up (greater conduction to the air, etc.), and equilibrium is reached at some point. A broad, relatively large copper bar is going to be able to dissipate a fair bit of heat, at least when compared with, say, a light bulb.

Conclusion: your copper isn't going to melt or get dangerously hot unless you do something completely unreasonable like short the battery through it or cover it in extremely effective thermal insulation.