Leaderboard

I evaluated the connections between the ground strap and the painted frame ground mount. The lug and the cable make good contact by a cylinder-in-cylinder connection and a crimp. The ground bolt and the frame nut are also a cylinder-in-cylinder connection (slight loss in contact due to threads). Both the cable/lug and bolt are about the same diameter so why is the bolt a bad connection? The problem is the only contact between the lug (and all the power in the cable) and the bolt are on the bottom of the bolt head. I estimated some dimensions and calculated the surface area of electrical contact for each connection. The more contact area, the better the connection. Contact surface area of ground bolt and nut (cylinder-in-cylinder) = 226 mm2 Contact surface area of the bottom of the bolt head = 69 mm2 All the current has to flow through only 69 mm2 of metal to metal contact. If you sand the paint off the frame you will greatly increase the contact area. Contact surface area of sanded connection = 209 mm2 + 69 mm2 = 278 mm2 The sanded connection can carry much more current for a longer time than the painted connection. Sanding this connection increased the contact area by a factor of 3. All these numbers are approximate but shows there are measurable gains to this modification.