Flippin out Amp guage

[roofman]

I recently had my Lucas alternator rebuilt, and today installed a new battery. The car started fine, but my amp guage is swinging wildly from charge to discharge, and my ignition light is flickering. What do you think is going on?

 

[DNK]

Time for an EXORCISM

 

[TR6oldtimer]

Check your connections. Sounds like something is making then losing contact. You may also have a bad wire. I hope it is this and not the rebuilt alternator although it too could have something lose inside.

 

[DNK]

i think that was a symptom of a bad alt.

 

[TR3driver]

I'd check the connections carefully, especially the sense connection (if you have one). But if nothing shows up, likely it's a bad rebuild.

 

[roofman]

If it is the alternator, what is it doing ( or not doing )?
Is there a test? I have one of those real basic battery / alt. checkers and it shows it charging. It did not do it until replacing the battery.

 

[Keoke]

Well this is just a guess. I think what you are seeing is a faulty regulator in the alternator.---Fwiw---Keoke-?

 

[TR3driver]

If it is the alternator, what is it doing ( or not doing )?

Whatever it is, it's intermittant. I would guess it's alternately working as intended, then not working at all.

 

[RonMacPherson]

The alternator is essentially an alternating current generator. One that is controlled by diodes(one way electrical switches) to convert the electrical output to direct current. If you ever see an oscilloscope screen of an alternator hookup you may find it very interesting to see that it is actually a series of bumps(voltage) that are controlled to a certain height(output). Then it is regulated to keep it at a "consistent" output by providing the field with a voltge signal. If the field sees too much voltage or the signal voltage doesn't reduce when voltage output gets too high, the alternator will overcharge.

How Stuff Works.com used to have a pretty good explanation of alternator construction, but that was several years ago.

 

[TR3driver]

Just a thought, you might double-check the ground path between the engine and the battery. Friend of mine had a similar problem on a TR250, that turned out to be paint between the ground strap and the body.

 

[roofman]

To finish this thread, could not find a prpoer Fiesta alternator, but did find a 43 amp Lucas, rewired to Moss instructions and I'm good to go. Thanks guys.