Using a fuse as a shunt resistor is a terrible Idea.
Oh, I've had worse.
Fuses are metal wires designed to melt at a certain current, and the element is very hot at that point.
Well, let's consider that:
(150 Amperes)^2 * 0.34 milliohms = 7.65 Watt
Not an inconsiderable amount of power.
But as I said, that current only happens when I start the generator or jump the truck engine.
20 Amperes is a more normal peak.
(20 Amperes)^2 * 0.34 milliohm = 0.136 Watt
I think that I can live with that heating effect.
You would be much better of by using a section of the red power cable ...
Well, a foot of 2 AWG only gives me 0.14 milliohms and the geometry is not as convenient.