I had posted this in another column about automotive "mistakes". But after the fact, I thought it really fit better here.
Not really a mistake on my part, but someone got sorely frustrated. I used to drive a '49 Chev 3800, basically a dualie when I bought it. The lock ring rims were dangerous to work on a tire. And 18 inch tires were expensive. . . ! So I converted(?) it to 16 inch singles. It had an OEM electrical system at 6 volts, which I converted to 12 volts. Except the foot starter. Built my own electronic instrumentation, but that is another tale by itself. An old battery with a shorted cell (I think), standing overnight it was around 8-10 volts. With a 6 volt starter of course, it started quickly even on cold mornings. And the generator was very forgiving, coming up to 12 volts in seconds, so all the lights worked the way they should. If it was running. . . One morning I went out and the hood was up and the battery was gone. I did lose a few hours but wasn't working anyway, so all it cost me was another "blem" battery. But whoever it was that got mine was in for a very rude shock. . .