Alternator query.

[Rabbie]

Dear Marge,
I have a boat fitted with a Yanmar 1GM engine. Previously, when switching on the ignition a red light marked 'GEN' lt up and stayed lit after the engine began to run. It never went out. I have now fitted an ammeter which shows that charging is taking place, but, when switching on, no red light appears, nor does it after the engine runs. Should I be worried?. Yours, Rabbie. /forums/images/graemlins/confused.gif

 

[Heckler]

depends
the light works by voltage feeding to/from the battery to alternator, the volts flowing the other way cancels the light out. possible the ammeter is allowing things to flow in a different way. this is the basic theory, i am sure that some smarty pants will know the definitive.
stu

 

[Stemar]

Possibly, but it's likely to be simple enough to correct.

One of the thin wires to the alternator is fed from the "ignition switch through the warning light to the alternator. It should have 12v at the alternator when the ignition is turned on. if not there'll be no power to the field coils to kick-start the alternator, so it will have to spin up pretty fast to self excite.

The most likely reason is that the supply from the "ignition" switch to the warning light has become disconnected, or the other end from the light to the alternator. Or the bulb may have blown.

Good luck

 

[Rabbie]

Thanks chaps - electrickery does my head in!. Rab.