One wire alternator - advice please

[canam-phil]

I have been using an alternator of the "one wire" type.

On the last trip I noticed that rather than the voltmeter indicating 13v plus when running its now registering 12 volts which is the non-running battery voltage.

All connections seem OK although I noticed a few 14 volt readings on the last trip.

Any idea what can be wrong?

A local well established auto electrical repairer seemed never to have heard on a one wire alternator and thought that the likely problem was a lack of wires to the alternator..

[jimmyfish]

buy one wire do u mean one main positive and one other wire

[canam-phil]

One wire direct to battery and the other connection via the case to engine/chassis.

[M3 Mitch]

Check the connections (particularly the ground) for clean and tight, if you can find an ammeter, particularly a clamp-on type, you could check that it's charging.

You should see some rise in voltage from idle up to say 1200~1500 RPM, then it should level off.

If not then the problem is likely in the alternator itself. Most rebuild shops will check them for free or at worst cheap.