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Steve Reeves wrote:
About 3 weeks ago I noticed for the first time ever a brief
overvoltage problem.... I cycled the switch and the alternator came back
online. A few more times the discharge light would come on, then start
"charging"
again with no input from me....
Steve,
I'll leave the recommendation about alternator size to others, but your
problem sounds like a classic case of defective wiring/loose connection to
me, most likely in the ground side of the system, or anywhere in the voltage
regulator part of the circuit.
Bob Nuckols' Aero Electric Connection, www.aeroelectric.com/ has an
excellent chapter on alternators/charging circuits. Well worth the read, and
much better trouble shooting details than below, but you need to buy his
"Aero Electric Connection book (recommended) to have access.
If you elect not to buy/read Bob Nuckols, start by looking for frayed,
damaged, or pinched wires, and check every terminal/connector in the
circuit. Corrosion and/or loose/broken wires are often culprits. Hate to
recommend this, but another area is a broken ground wire inside the
alternator, especially if it has a built-in voltage regulator.
The third likely culprit is the voltage regulator itself. Even if it's not
bad now, continued operation under the conditions you describe will likely
fry it in short order. This is to say, if you find a loose connection/broken
or frayed wire, you can fix it and assume that as the problem if this
restores normal operation. If, however, you replace the voltage regulator
without checking out the wiring, don't be surprised if the condition recurs
in short order...
An easy test is to replace the regulator and then the alternator in
turn--after checking the wiring and finding no faults. If you don't have
access to "loaners" for testing, these can be bench tested for a nominal
charge at a good repair facility, or at a local auto generator shop
(assuming an experimental aircraft).
Hope this helps!
Bob Pastusek
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