Power loss through brass bolt terminal lugs, gut feeling?

[KrisKasprzak]

I made a current measuring module based on a hall-effect sensor. The sensor will measure up to 20 amps, 80 amp peak for a few milliseconds during the 24 VDC motor startup. To connect the power leads to the module I have ¼” x 20 brass bolts (which are bolted to the circuit board inside my module. The length the current travels through the bolt is around 0.25 inches.


I'm measuring current with my Teensy 3.2 and it works perfectly.


I’m worried about power loss through the brass bolts. Note I chose brass over steel as the conductivity is better for brass. My question is how much power loss would there be through the brass bolts? From my calculations using the conductivity of brass is like 64 nOHM/m so the loss is around 0.003 watts. Sound right?

Thanks in advance.

Kris

 

[GremlinWrangler]

The higher losses will probably be in the metal to metal contacts, especially if you end up with a corrosion layer in there which can make life interesting as each time you take it apart the results change. Working out the current path through the bolts/nuts/washers and making sure you do not have any point connections (say on a split spring washer) is a good idea, as is making sure those surfaces stay clean.