how to tell if alternator is bad?
 

What are some signs other then dimming lights that a alternator is going bad? Tonight everything seemed fine with my truck untill i went to start it after leaving barnes and noble. I put the key in and tured, heard a pop then eveyrthing went dead. Nothing worked at all. Called triple A they came and gave me a jump start. It worked but i couldn't believe i needed it. Its a brand new battery purchased in september.

What else could've caused what seemed like a short?

how did it act after it was jumped? if it acted kinda' funny, like it had lost power or maybe the radio or something was dim or faint, it probably is your alt. i've been going through some charging problems my self the last few days. there are ways to check it, but most auto part stores will do it for 'ya free.

You might have blown a fuse link. I don't believe an alternator would make a pop, plus you lost all power.

Usually is what i do, is take off the battery terminals and see if it is still running, if it dies, it is not charging. Just just it is not charging, does not mean the alternator is bad, could be the regulator, or the wiring. If it keeps running, for the moment it is fine. Something might be grounding out, and you hearn a loose wire connectoin weld its self to something.

I do not recommend taking the battery cable off with the engine running. You can blow up stuff in a hurry. I learned this the hard way. Pulled the cable off a pickup I had onetime, it ran for about 10 more seconds and then quit. Would crank but not start after that. Know what I did? I blew the ignition module. Lesson learned.

As far as the original problem, I would try the easy stuff first. I would take the battery terminals loose and clean them.

Removing a Battery cable from a vehicle While the engine is running will blow diodes & destroy your alternator.
Tye voltage regulator is what determines the voltage flow not the alternator.

That's why the headlights dim at idle, the engine has to reach at least 800 rpm to have the VR kick in and provide extra power.

Removing the battery cable:

You guys are behind some 40 years as this practice was used on [size-4] Generator type vehicles[/size]

It was done to SPIKE the system to get the generator/voltage regulator to work.

when it got jumped the idle was off, not normal at all. If i turned the wheel to much the engine would die, if i came to an abrupt stop it would die or just stop at a light it would dip down to almost 100rpms then go up to 700rpms then even out at 400rpms.

It did this today today but not nearly as bad. The lights would dim as the rpms dropped.

Whatever did happen it feels like I have another engine in my truck. It feels like there is more power.

What could've caused this problem? I mean it ran fine before i went into barnes and noble. When I put the key in it lit the dash up like normal but as soon as you go to START everything went dead. I don't get it.

Clean all the connections & grounds at the starter solenoid, V/R,Battery

Drop by autozone (and about 10 other chains) and let some kid check it for free. :rolleyes:

not to sound stupid but what would cleaing the connections on the starter have to do with anything? It's not like it wanted to crank there were no lights on the dash nothing lit up, no noises at all. Where is the V/R located? Battery terminals are clean as can be.

while the truck is off, try the lights. if lights are dim or dead, then it isn't starter connections. i have a feeling it probably is you're altenator. the only weird thing is that popping sound. try and see if batt. takes charge with external charger. or if you have a voltmeter in truck or a handheld multimeter, then jump off truck and check if voltage raises, if so then your alt. is good.

I never said starter, I said the starter solenoid,plus all the cables & mounting areas.

Everything connects to the Voltage Regulator(V/R)

For Peace of Mind
You want to MAKE sure that everything is CLEAN ,TIGHT & making good contact before trying to trouble-shoot the system.

That includes the Mounting area of the V/R & starter solenoid.

where are all these things located? the poping sound i heard wasn't to loud. Maybe it was just everything just shutting off that made a noise.

It was that small piece of lead that was still in contact with the battery burning away at the battery/cable connection as the rest of the battery clamp was insulated by corrosion and or crud!

The man said it more than once, and he was right, "so pretty please, with sugar on top, clean the friggen connections!"

In part (the last two lines) shamelessly stolen from Pulp fiction!

well i took some thin pieces of lead and hammered them flat and put them on the terminals. It helped alot. Terminals weren't dirty. The negative bolt was tightened all the way but it slid off easily.