Alternator Field Disconnect

[psaprop]

Is AFD necesary on the newer outboards? I haven't heard much about it lately.

[Joe]

No, unless you feel the need to disassemble your alternator to attach the AFD pole leads from the switch to the voltage regulator. And even if you did this(?), you won't need it. The AFD feature is really only usable for an alternator with an external voltage regulator, and very few marine engines have this anymore (at least not Mercruiser or Volvo that I am aware).

Aside from having the correct sized switch to handle your maximum amperage, the next most important thing is to have a switch that has "make before break" contacts; but most, if not all new switches have this feature.

[yandina]

Even make before break switches have an "OFF" position. Turning the switch to OFF while the engine is running is inviting alternator damage. If your motor already has field disconnect cables back to the switch location, by all means use them but I certainly wouldn't go to the trouble of adding them to an existing installation. First move is a label on the switch that warns against turning it off while the engine is running. If you think there is still a possibility of someone doing it, add a ZapStop to the alternator although I would like to think that modern motors already have one.

[Joe]

Well if someone is cutting the battery switch off while the engine is running, maybe they shouldn't be using (or even in) a boat. I'm not sure its' possible to idiot proof everything.