Bob Palmer wrote:
>Steve,
>
>.................That is, unless there's heat conducted from the
>ammeter back through the wire to the alternator terminal. This doesn't sound
>likely. What might better explain what happened is the heat caused the
>ammeter to short to ground, and of course that would cause the alternator
>output wire to heat up. Then when you bypass the ammeter, the short goes
>away and the problem is solved.
>
>..........I completely agree with substituting a voltmeter for the ammeter
>because
>it's more informative to know what the voltage of the system is under
>various conditions................
>Bob
>
Bob and Theo:
You're probably right that the ammeter wasn't heating up enough to get the
alternator wire beyond 190 degrees and climbing (although the face of my
ammeter is "bubbled" and distorted in a few places, so the guage itself has
definitely been overheating). The ammeter got a lot warmer to touch than the
other guages, especially with the AC on. It was still working this morning, by
the way, even with the high temp wiring, so wouldn't that indicate that it had
not shorted out, or is there such a thing as a partial short? If heat could
cause the ammeter to short, but resistance in the ammeter itself could not
cause a heat buildup, then where would that heat come from? Couldn't it be the
case that if the ammeter is rated to measure a certain capacity, and the power
going through it exceeds that capacity, heat is going to result? A year or so
ago I substituted a 35 amp ammeter for my 50 temporarily on the theory that I
would be able to see the needle move more noticably. It sure did, as whenever
I started the car, or turned on the AC, the needle would peg all the way to the
right and stick there. My 50 amp ammeter barely moves in the same
circumstances, so I don't know if that tells you anything.
And finally, are Mo-Ma, the Ferrari guys, and the Mad Wiring guy all wrong
about ammeters being suspect to melting down when exposed to excess amperage?
By the way, after a few "sparking sessions" under the dash through the years, I
have finally learned to disconnect the battery when playing with electricity.
Steve Sage
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