TeamD Adventures

Welcome to another edition of Fundamental Physics In Everyday Life. Today we’re contemplating the subset of the universe demarcated by the 3-space boundaries of your vintage car. We’ll be diving into the car’s electrical system to explore power flows.

Let’s start with a quiz question:  What does the second law of thermodynamics assert?

• 1.   A pointed object or sharp edge concentrates energy at the tip or along the edge.
• 2.  Energy flows from hot to cold.
• 3.  An increase in the volume of electrical energy lowers its pressure.

I’m glad we’re all on the same page here — the answer is #2.

But I hear the smart-alecks in the back asking,

“This law nicely describes the working of the radiator, but what has it got to do with the electrical system?”

Well, I could say that the physics of energy do not depend on of the form of the energy; thus a similar (in the strict sense) law would describe the working of the auxiliary lighting system — but I’d rather admit that my scientific-sounding opening was a mere gambit* to attract your attention, and jump quickly to the photos.  I’ve been working on the

Here’s the nose of the ’83 Audi, showing half of the aux light brackets and a moose-pipe full of wires.

Yep, I’m omitting the inner factory headlights, which would have been obscured by the driving lights anyway.  I’m hoping that the additional airflow through those empty headlight-holes may offset the flow blocked by the Hellas.

Here’s the fresh ground point for those lights.  Ah, that battleship grey enamel makes me homesick for the service. “Lay it on, cut it off”.

A couple of circuit breakers bolted to the alternator. When I got it, the car had a hot lead coming off the alternator output running straight to a relay and then to accessories… and not a fuse in sight. <yeek!>

Custom “Y” jumper to feed the breakers.

I’d have routed all the juice through one, but (does some quick figuring of watts divided by volts…) 420 watts of lighting pretty much eats up one AWG 8 cable. If you’re gonna run the radiator fan, too, ….

* Well, okay — I was thinking that earths are terribly important in older cars, and isn’t it funny how a car’s isolated from the Earth by the rubber tires, so has its own “relative” ground. Er, earth potential.