Improving your troubleshooting techniques

by admin on December 13, 2017

Practice makes perfect!  (or does it)

This is an expression often heard as a child when learning something new like playing the piano, or any musical instrument for that matter. It is used in sports, whether it is the child learning to throw and catch a baseball or pass a soccer ball or even tying a shoe. It applies equally well to the older person learning golf and how to swing the club. It applies to anything that we do or expect to do on a repetitive basis. Most assume that it only applies to muscular activity, but it applies to the use of your brain too.  (Remind me for examples)


As you know, or might have guessed, I love to know how things work. I know of nothing that doesn’t benefit (in my mind) from a complete understanding of its’ internals and therefore being taken apart. For example, after learning to drive and having the car working well for a year, it quit on the way home from football practice. The symptoms were that the it the “idiot” light for electrical came on and the car stopped. In the dark the tow truck guy peered into the battery and said I had no electrolyte it had all evaporated. It was as if I had no battery.

Collect Data, Analyze Symptoms

After getting the vehicle home, I did some initial inspections the voltage was around 12 volts, a bit low. As previously mentioned, all of the battery cells were completely dry (this was before the advent of “maintenance free” batteries. I carefully refilled all of the cells with distilled water and ran the engine at a high RPM to charge the battery. Everything seemed fine. What didn’t make sense was that the electrolyte was gone. I decided to check it every couple of days. I got a piece of notebook paper and made a simple table showing the date and cell number. I stuck a plastic drinking straw into each cell and recorded the level. I noticed after about 3 days that one of the cells levels was dropping faster than the others. In retrospect, this is not unusual as the battery is actually 6 distinct cells. I decided to check the electrolyte level again, but with the engine running. This time I noticed in a couple of the cells there were bubbles. The bubbles kept coming. Having read a bit about the lead acid storage battery and the basics of the automotive electrical system, I knew that these were gas bubble of either hydrogen or oxygen. The gases are formed as a natural part of the charging cycle. The thing that was interesting to me was that I could see them. Perhaps the water wasn’t evaporating but rather electrolyzing. Perhaps a problem with the charging system? One thing I tried was to rev the engine while looking, I could see the battery “boil” and all cells bubble as I increased the RPM. My thought was that the voltage regulator wasn’t reducing the signal to the alternator so it was overcharging the battery. Essentially all unused output into the battery…

Research

So back to the book store to read some more on electrical systems. (Although the internet had been invented it, was largely in use by academics and military.) I read a book on the automotive electrical system and learned all I could about the voltage regulator. In those days, it was a simple relay. The basic premise of operation was that if the car was on and the alternator running, it would control the amount of current to the field coils of the alternator to adjust the output of the alternator. As the demand for current went up, it would increase the signal so that the output would increase. It was essentially a relay that shut it’s contacts if the sense voltage got low and opened if it got high… OK. I took my multimeter and using the techniques described in the book, verified that the regulator opened and closed its contacts at the right voltages.

Uncle!

Admitting defeat, I took the car to my mechanic. They worked on it for over 4 hours. I, being the nosy teenager that I was, was right alongside them the whole way, “correcting” them and pointing stuff out to them. They determined that the alternator was fine and could produce plenty of output. They determined the battery was very sick and should be replaced before it got really cold. I said I’d wait until we knew what was wrong and was corrected before putting in a new battery.

Defeated, Yet Again!

After spending all morning on it, and baffling all four of the guys in the shop, they admitted defeat. “OK Kid, go down to Dan’s Auto Electric and ask for Dan, no one else. Tell them I sent you, and explain the symptoms, you know them as well as we do, and you know what was checked.”   [to be continued...]

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