What does this sound like?

[Quiksilver]

1996 Ford Thunderbird
4.6L

I seem to be having an electrical issue with my Thunderbird, you see at idle the alternator doesn't want to charge the battery, however once I step up the RPM's (eg. press gas pedal) it charges just fine, but once I reach the idle RPM again it drops back down.

I've already replaced a few parts and it hasn't helped...

- Cracked battery terminal (needed to be replaced)
- Voltage regulator (had no effect)
- Alternator (Bought a used one that checked out fine at a junkyard...)

None of them has solved the issue yet... so I'm thinking Alternator brushes next... (I'd have to specially order them though.)

Would bad brushes cause this issue?

I've checked the voltage used a voltmeter of all my electronics and none of them are pulling an abnormal amount of current so I don't think a short is the issue here.

Anything else I should check?

Guy at my work said I should check spark plugs and wires, but if they were bad I would think I'd see more symptoms than this... I will probably be replacing them soon anyway as I'll be doing a tuneup on my car next week or so.

Sorry if It seems a bit scatterbrained I'm just tired and trying to recall everything...

 

[HannibalX]

All Ford 4.6L V8s use a combination voltage regulator/alternator unit. If it were me I would buy a new (reman) unit and a new battery. Car batteries don't like to be deep cycled except for a few high end models. Your average car battery is going to take a dump when deep cycled often, like when having alternator problems. Also, a dieing battery can cause a short circuit in the voltage regulator to begin with. Also, just an FYI your average car alternator is not designed to charge a battery from zero so if you decide to go with new hardware make sure you charge the battery prior to putting it in the car.

 

[Quiksilver]

Well the voltage regulator is brand new and is currently being used on the Used Alternator (that works just fine.), also at the moment the battery is fine too. It's a Duralast Gold model and I haven't let the voltage get low enough to where it gives me low battery warnings or anything.

 

[jlee]

What's the alternator putting out at idle?

 

[LTC8K6]

What makes you think the alternator is not working at idle?

 

[Pacfanweb]

Brushes won't cause this problem.

Have you had it tested to see if the alternator is working properly? It's not supposed to do much at idle. You can do a rudimentary test yourself if you have a meter.....let it idle with no accessories on, an you should be getting about 14.2v at the battery.