Tuesday, October 29, 2013

Alternator replacement

[Incomplete 10-29-2013]

The original alternator wasn't charging, so I replaced it with a new "spare" that came with the boat.  Except for the word "Lucas", neither alternator had any significant markings to indicate model or connections, so I had to figure it out.

Alternators

The original alternator was connected by four wires as follows:

  • To the batteries isolation diodes to charge the two battery banks. B+? (Brown)
  • From the charge light on the control panel to energize the field coils (using the "start" battery).  F?
  • From the house battery through a relay controlled by the key switch.  This is probably to sense the charge voltage.  S?
  • To the tachometer. W? (Blue/Black)
The new alternator had two connections, presumably B+ and F.

I'm unsure of that capacity of either alternator.

Modifications
  • Using the original alternator as a guide, I soldered a short blue wire to one of the stater coils for a tachometer feed and then reinforced it with heat shrink tubing where it feeds through the cover.  I crimped a female bullet connector to the other end.
  • There is no place for a"sense" connection, so I taped up the existing wire and left it hanging for now. It leads to a relay.  (Later I plan to remove the extra wiring and relay completely.)
  • I painted the pulley with two coats of "Ford Blue" Rust-o-leum Engine paint.  (It turns out that my engine has Chrysler blue paint.  I like the Ford color better and the Chrysler paint job is crappy, so I decided to stick with the Ford color.  It will also help show where I've repainted.)
Technique

Wrenches used:

Results
  • Puts out 14.1 VDC charging voltage
  • Tach still didn't work.  It's probably the tach, but I need to check voltages.  Not sure what to expect here





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