OK, so I got my alternator fixed, but there's a story that goes along with it...

https://www.f150online.com/forums/sh...d.php?t=265798

So I'm driving to work today and about the 15 mile mark there's smoke rolling everywhere and the fumes fill the cabin. Pull over and raise the hood and my brand new alternator is just billowing smoke. Side note**about 30 seconds before I could get pulled over, the actually battery light (the one that looks like a battery) came on** I thought, this is just great, what did I do wrong? Long story short, got it swapped out with another one and just complete dumb luck I got a bad alternator from the parts place. Second one is just fine. But this has led me to some questions...

1. When the orginal alternator went bad, the truck obvioulsy ran fine until the battery was completely drained and could no longer support the truck, right?? So, since the battery gauge reads battery voltage, how come when idling the gauge was down completely in the red, but when you revved up the motor the gauge would increase back to the normal zone?? Was the alternator still putting out some voltage to register on the gauge but just not enough to charge the battery??

2. The battery light is supposed to come on to indicate "the battery is not being charged properly". And it came on today when the alternator fried. Why did it not come on at all when the original alternator went out??

3. Why do we even have a gauge for battery voltage?? By the time it reads low you're already in trouble...it's too late. Just liike with my first alternator...it went bad but the gauge never told you anything until the battery was too far gone. It shoulld read what the alternator or the system is putting out...yea??

 

You've found out why they are known as Idiot Lights. Did ya also know the oilpressure gauge is designed not to move? Same for the superduty trucks tranny temp gauge.

But to answer your question #1, yes that is very likely what happened.

Adrianspeeder

 

Ohh yes, I know that about the oil pressure AND the water temp gauge!!! But, I figured the voltage gauge is real, just useless.

 

Heard lots of horror stories about the rebuilds -Alternators , Starters, Compressors.

I replaced both my units with factory takeoffs off eBay from 30-60 bucks- It's a little safer lol and you get the stuff cheap..

 

1. The light doesn't do exactly what you think, and the alternator was not necessarily the origin of the first problem. It's possible that the battery went bad first (no ALT light; voltage OK for a while), and that burned up the alt. Depending on exactly HOW the alternator (more likely just the voltage regulator) crapped out, the light might not come on.



2. See above. That's not what the light with a battery icon means.

3. Again, you're not understanding what the volt gauge is telling you. It shows voltage AT the dash. Not at the battery; not at the alternator. If you have perfect connections between the dash, the alt, & the batt, then their voltages will all be the same, which is what the gauge is for. But if you let the battery terminals get corroded/loose/damaged, or if your wiring harness connectors develop problems, it will be increasingly INaccurate. A volt gauge is VERY useful for watching what your charging system is doing, IF you pay attention to it & learn exactly where it normally sits. If it drops while the engine is running, then your alt isn't keeping up with the electrical load & your battery is DIScharging. The farther it drops, the faster the battery discharges. But you still have time to do something about it since the battery stores a LOT of energy, so you could drive with no alternator for a hundred miles (if your battery is good & you minimize your other loads).

 

No problems with the battery. Brand new Optima. Also didn't know I had a ALT (alternator???) light.


That was ver batum what the owners manual says the battery light means...that's why I put it in quotation marks. Not saying your wrong, just that that's what the book said. So what does it mean then??

I fully understand this and agree/understand what you are trying to tell me. The problem/situation I experienced does not jive with what you say though. My gauge gave no indications of fluctuation/movement until it was too late. Theory is because of the Optima battery it hung on til the bitter end, then it was too late. But in my situation, I had zero warning. Like I said, by the time my gauge started telling me something was wrong, I had no time to respond and ended up stranded. No telling how far I drove with just a battery...which referrs me back to the comment above about knowing I don't have a battery problem.