One day my kid will ask me: “Dad, how do engineers work?” and I’ll tell this story.
Engineering and Motorcycles#
While the motorcycle isn’t riding and is wintering in the parking lot, its battery needs to be charged from time to time. For convenience, people usually run a little cable with a connector somewhere accessible — so you can plug in the charger more easily.
One spring, at the start of the season, it was time for me to charge up. I plug the charger into that connector — and it’s a smart one: it lit up a special indicator saying “polarity reversed” and, rather than damaging the battery, simply refused to charge. I thought to myself: damn, whoever installed this cable really managed to mix up two wires.
Good thing the charger also has crocodile clips: I pull off the seat, pull off the second one, unscrew the cover, clip onto the terminals, leave the disassembled motorcycle to charge, and promise myself I’ll sort it out and reconnect it properly.
A few months pass. Time to charge again. The task “fix the charging cable on the motorcycle” is still sitting in my to-do list. I grab the multimeter — need to find the right terminals out of three on the clamps — grab the wrenches, disassemble the bike: pull off the seat, pull off the second one, unscrew the cover. I find with the multimeter which contact the black wire is connected to. I grab the charger, measure with the multimeter where the positive and negative should be — the multimeter shows 15V when connected correctly, and -15V when the polarity is reversed. Having figured out where the positive and negative are on both the charger and the connector, I start thinking and pondering — how did the mix-up even happen? It seems like, based on what I measured, minus goes to minus and plus goes to plus. Late in the evening I’m trying to work out in my head how 1 and 1 add up, what goes where, and what the actual problem even is.
I roll the motorcycle to the outlet. Without changing anything, I plug the charger into the motorcycle’s connector and plug the charger into the wall. It charges. I screw the cover back on, put the seat back, put the second one back.
That, my children, is how engineers work…