Made it home by the skin of my teeth....

[peterbrown77]

Driving home last night with kids in the car, I thought my headlamps were kinda dim - I even remarked on it to my daughter. I don't drive my EB all that much (15mpg) but I said, wow - those Corolla lenses are really good.

Anyway, I noticed my voltage meter was way down near L and getting worse and I had 30 miles to go. Turned off everything I could - a/c, high beams, stereo, fog lamps. By the time I hit my driveway the headlights were like a weak flashlight and there was barely enough left in the battery to turn over the engine again. The battery I just replaced a month ago, BTW, with a Walmart one.

So a rebuilt alternator is about $180 at Autozone and a regulator is like $50. I'd like to try the regulator but I'm willing to bet that if it isn't the problem, they won't let me return it so it'll be a $250 job not a $200 job.

So how do I know if it's the regulator or the alternator?

A few facts: The voltage gage would rise slightly if I revved the engine. Also, when I restarted it at home it seemed to come up even more from L but not to the middle of the gage. Lights were brighter too. The battery is new and I've had it on a charger overnight. The "Check Charging System" did not come up on the trip computer display until I was in my driveway and back at idle (the whole drive was highway, turning about 3K rpm (thanks to my tow package)).

TIA

 

[2TimingTom]

Isn't the regulator built into the alternator?

And you're correct, Autozone won't do a return on electrical equipment.

 

[ragajungle]

when you replace the alternator you should replace the tensioner if you havent yet. just a thought.

 

[yavapaires]

I would go with the alternator. That way you will get the regulator too. If it charges with increased RPM, that indicates to me you have a bad alternator. If it were me, I would pull the alternator apart and check the brushes. Depending on the mileage, I would bet the brushes are worn out. Too many places just replace instead of repair. Pull the alternator off and spin it by hand, checking for any unusual sound, grinding, growling, squeaking. Then pull it apart and look at the brushes. If brushes are worn down to next to nothing, it will not charge.

 

[peterbrown77]

Yes, the regulator is internal to the alternator but I can open the case and replace it.

I'm trying to do this for cheap because I'm starting to get a little of the Ford disease (rust, on a car that I've garaged it's whole life) and I want to trade it in for a Hummer H2 when I find one. I figure if you're going to get crappy fuel economy, why not go in style?

Anyone know a test I can do to isolate the regulator as the issue?

 

[SoNic67]

Don't bother with the regulator... Usually what happens is that one or more of the rectifier diodes fails (usually when you start the car after you leave the light on and drains the battery). In my alternator the temperature of the shorted diodes was so high that melted their solder points.
Even if you replace those (it's a pain), then the bearings are worn out, so next time you replace the belt or tensioner, they will fail.
Brushes (on the collector) also can be worn out or damaged.

If you really want to check the regulator, usually there is a screw on back that can be grounded and that will by-pass the regulator and put full voltage into battery. Do it ONLY at idle rpm's.

 

[peterbrown77]

My son did kill the brand-new battery a couple of weeks ago by leaving the key on when he moved it to get at the lawnmower....

I fully charged the battery overnight, got 12.7 volts on it this morning, started the car and got 14.24 V....

Would that do that with bad diodes?

 

[RomeovilleIL]

180 is a bit much for a rebuilt alternator. Shop around & you should find a rebuild with guarantee for about 130 (RockAuto/O'Reillys).

You mention you dont use the truck very often & are thinking of trading. Most salvage yards I've been to run 50 for a used alternator with 6 month waranty. Ebay has tons of used with warranty around $40 delivered.

 

[SoNic67]

I fully charged the battery overnight, got 12.7 volts on it this morning, started the car and got 14.24 V....

Would that do that with bad diodes?

That is OK. Problems apear when people try to charge a completelly discharged battery on car, straight from an old alternator.

 

[budwich]

My son did kill the brand-new battery a couple of weeks ago by leaving the key on when he moved it to get at the lawnmower....

I fully charged the battery overnight, got 12.7 volts on it this morning, started the car and got 14.24 V....

Would that do that with bad diodes?

Actually, that depends on how or should I say what you measured it with. A failed diode in the bridge may cause a loss of DC voltage BUT depending on the instrument used, not all meters read DC that has "ripple" correctly and thus could still read 14 volts "DC" but not really.

Further, it is likely that IF the voltage is correct, then the regulator is working... its regulating. Your problem may be more of a current issue or lack there of. IF you are lucky, perhaps you can get your alternator tested at one of the parts stores for "free"... of course, nothing is ever free but might be worth a try.