The ADAGIO crew has had the good fortune locating exceptional marine services talent in various parts of the world – ranging from Hobart, Tasmania to Sitka, Alaska. Recently we had an especially good experience in San Francisco that I just want to mention briefly.
ADAGIO has two Electrodyne 70A, 24VDC brushless, roller bearing, heavy duty alternators. The Electrodynes function primarily as a backup to our 10kW Panda genset, but of course keep the batteries charged up if we are motor-sailing. Since we are accustomed to such as autopilot, radar, and fresh-baked bread, we like to be confident that a genset failure that we cannot repair at sea doesn’t cramp the electrical consumption too much.
So we inquired around our network of experienced Bay Area sailors for a recommendation of the best engineer to give the Electrodynes a thorough inspection. More than a couple of skippers recommended Michael Daley. Coincidentally we came across an excellent technical letter that Michael wrote for Richard Spindler’s Latitude 38 of February 2009 — specifically on the topic of alternator reliability. OK – that made it an easy decision.
Michael was at the gate of Marina Village Yacht Harbor within 1 minute of our 0900 appointment. Over the next seven hours Michael and I went over that whole end of the yacht’s electrical system with a microscope.
Today via email we received Michael’s invoice together with one of the more extensive reports of our experience. This is what we should expect from all the technical staff that work on our boats — but in our experience it is exceedingly rare. Here’s the report:
Electrodyne alternator produces rated output only at excessive engine RPM.
Field-coil connections are a concern.
1) Inspect installation: Installation was professionally and competently done, except for the field coil connections. These use bullet connectors, and they do not match the wire guage, leading to corrosion at the exposed wire ends.
2) Measure pulley diameters and calculate alternator-to-engine RPM ratio: The ratio is too low to allow rated alternator output at the desired cruising engine RPM.
3) Inspect belts for quality, alignment and tension: The port engine has high-quality belts installed, but the Starboard alternator belts are not well matched, and are standard quality. Tension is sufficient for operation at moderate output without significant slippage, but higher tension is suggested (see recommendations, below). The surfaces of the pulleys are not as smooth as they ideally would be for longest life and minimum dust production. (see recommendations, below).
4) The port alternator field wire is not a quick-disconnect connector, as on many alternators, but it is also not on the stud-connector that Electrodyne typically uses. The field wire emerges from a hole in the alternator cover, where it is crimp-spliced to a short piece of wire leading to the bullet connector. This is problematic. Alternator was purchased in New Zealand.
5) Consult with Electrodyne factory: Factory suggested that the unit had originally been fitted with an internal regulator, which was removed in New Zealand when Steve ordered an externally-regulated unit. The field wire stud was not installed, as it should have been, but the wire was simply routed through the hole in the rear cover. The factory suggested disassembling the unit in the hope that additional field wire was available inside.
6) Remove port alternator from engine completely for access.
7) Disassemble port alternator to access field wire inside rear cover.
8) Unfortunately, there was no more field wire inside.
9) Extend field wire using adhesive-filled, heat-shrink crimp splice to allow a service loop for future work.
10) Delete bullet connector entirely — is unit must be removed, there is now enough extra wire to allow it to be cut and respliced.
11) Reassemble alternator.
12) Reinstall alternator.
13) Swap two belts, which had measured different tensions previously, and adjust tension.
14) Replace splice on starboard alternator field coil with adhesive-filled, heat-shrink crimp splice and extend field wire to allow a service loop for future work. Starboard alternator had enough field wire left to work with without removing or disassembling it.
To achieve rated output at preferred cruising engine RPM, the alternator pulley ratio must be increased. The crankshaft pulley diameter must be increased to do this.
1) Replace crankshaft pulleys (port and startboard) with a larger diameter. If possible, use an even larger diameter pulley that would allow the alternator pulley diameter to be increased also, which would result in longer belt life. Objective is to obtain 4800-5000 alternator RPM at cruising engine RPM. In any case, the alternator pulleys shoud be replaced, since the working surfaces are not as smooth as they should be.
2) Operate belts at a slightly higher tension than was found, at least until a larger alternator pulley can be installed. This will reduce slippage and dust production. The only downside is reduced alternator bearing life, and these units are beefy, and should provide long service life even at the higher tension. If a larger alternator pulley is installed, tension can then be reduced somewhat.
3) Replace regulator with Balmar Max-Charge, with optional battery temperature sensor installed.
4) Balance the alternator field winding resistances, as was discussed. The best way to do this is to run the engines at exactly the same RPM and balance the alternator output currents by adding resistance to the field winding of the alternator that shows a higher output until they are equalized. (I’d be glad to help with this if you like). Otherwise. a careful measurement of the filed resistances measured AT THE REGULTOR should be made, and these resistances balanced.
For any of your projects, you can contact Michael as follows:
Redwood Coast Marine Electrical
1120 Brickyard Cove Rd.
Point Richmond, CA 94801(707)480-8517 (C)