Altenator or what??

Question

II have a 1996 4.3L Ext Cab 4WD Chevy S-10 - Twice this has happeded - I can drive it and the Battery light will come on and the battery will drain as if the alt. is bad.
I was stranded - a guy stopped and gave me a jump - I drove as far as I could when the Battery drained and the engine stalled - This time I had to walk to a friends house and get him to give me a jump - when it started the indicator showed me that the battery is now charging, and ran fine till I got home (23 miles) - this happeded 2x's both times the alt. indicator read positive charge after the truck sat awhile prior to jumping - What's going ON!!!! The connections are tight. Is the alt. over heating? It dones't feel warm.

Answer 1

The connections can be tight as possible, but corrosion can still occur in those tight connections especially if you live in northern states where they salt the roads.

First off, before you attack the connections...do what you feel is easiest first. I suggest getting a multimeter to check what voltage output is coming from your alternator to the battery while the car is running. Put the positive (red) cable of the multimeter probe on the terminal coming out from the alternator or directly on the positive terminal of the battery. Put the negative probe of multimeter on neg. of battery or engine casing. You should get above 14 volts for a good alternator. If it is less than that, don't assume it is a bad alternator yet.

Second, disconnect and clean all connections at the battery, alternator, and starter motor. Don't forget to clean all connections that ground to your car body or to the engine casing! Start your car up and repeat step one. If your voltage jumped up above 14 volts then it was probably a corroded connection. If not, check the tightness of your drive belt to the alternator. If it is a serpentine belt then you only have one belt to check because it makes everything rotate. If you get below 14 volts then it is probably a bad alternator. If you get a new alternator and the voltage still is below 14 volts, then you might have a ground somewhere or I'm stumped?! Remember if there was no improvement when new alternator installed, you can return the new alternator for a refund.

Third, you could have an internally damaged battery (causes random battery failure or poor performance) or battery needs water or it is just the end of the battery's useful life. They only have a useful lifespan of 4 to 6 years, this becomes more noticeable when trying to start/run a battery in cold weather when more amps are needed (cold cranking amps or CCA). You can check to see if your battery needs water by using a hydrometer:
http://www.uuhome.de/william.darden/carfaq4.htm#hydrometer
Remember to only use distilled water since even trace minerals can shorten your battery's lifespan a lot!
Remove your car battery and bring it in to NAPA auto parts or some other car parts store and request that they perform a "load test" on that battery. If the battery fails the test then all you need is a new battery.

NOTE: When you reconnect stuff in your electrical system back together try using dielectric grease to reduce future corrosion problems.
See why it helps here:
http://www.brickboard.com/ARCHIVES/1998JAN/7808.shtml

Hope you nail your problem

In response to the answer directly below
Disconnecting the battery while the car is running is a poor way to test whether or not the alternator is good or not. This subjects the electrical system to voltage spikes since the battery acts as a buffer.

Answer 2

A way you can tell if it"s the alternator that doesent work just turn on car disconnect the wirers from battery wile it runs. If the car turns off it"s possible that the alternator is bad. The alternator should be able to power the car with the battery disconected.

Answer 3

you could have a bad ground or the alternator could be bad. best bet is to go ahead and replace the alternator, and redo the ground terminals on the van (take the terminal off sand the contact point and add some dielectric jell, auto zone .95c,)

Answer 4

clean the battery posts and terminals. The meter says your alt. is wopking but it may not get to the battery.