Sorry if this is a easy question for others, but exactly how would I know if it is my battery or alternator that is bad. The vehicle won't start at all, no lights, accessories or anything. Thanks!

 

I'm thinking connection problem.

You can take out the battery and have a parts store load test it to find out if it is good or not. Same thing with the alternator.

Most Auto Zones, Checker, or any large part company will do this service for free. I prefer Auto Zone.

By the way, no question is a stupid one if you don't know the answer to it.

 

here is how to tell if it is the bat or the alt. have someone jump start your truck, then unhook your battery. if your truck stays running without a battery then your alternator is fine.

 

I had a problem once with my Trans-Am with the alternator working just fine until it got hot - it would do that if I was idling or moving slow, as long as I was moving the air kept it cool and working. The Voltmeter told me that, I would watch it go from it's normal 13/14 volt range to almost the bottom when I was sitting or moving slow - once I started moving a bit faster, it would move right back up again.

I'd definately get that battery tested first, if it's good - then the alternator. If both are showing good, take a real good look at the wires. A bad alternator can really cut a battery's life.

My T/A's sitting in the driveway right now with a bad battery --- and a good alternator, heh

 

Dude this is not advisable anymore. Overage goes into the battery to charge it. If you remove the battery the overage goes into the system. This is why it bogs the motor somewhat.

The ultimatum of this practice can raise hell with you computer as well as numerous other problems.

Just get it tested.

 

first i'm not saying to just drive the truck around without a battery. just pull the negative cable and see if the truck stalls. second there is no such thing as overage, the alternator puts out the same voltage with the battery dead or full. thats what the voltage regulator is for. it keeps the voltave between 12 and 14 volts.

 

The engine takes it 12 volts. It takes 12.7 volts to equal 100% capacity. Therefore alternators make ahigher average of at least 12.7 volts up to 14.3 volts to adequately charge the battery. A voltage regulator is built into the alternator on our rigs. The regulator has a bleeder. Basically, the regulator is a gate on the system and blocks the outgoing voltage to 12 volts. The rest of the voltage is bled via the bleeder. This overage of voltage (bleeder) is directed into the battery by way of an open loop. This is how the battery gets charged. Remember this is an automotive battery. CCA's are needed to start a auto right?

If you take the battery out the overage has no wear to go. So it overloads the regulator. This overload even for a second can blow the regulator allowing all the voltage to enter the system. Thus blowing it!

I know what you meant by only for a second or two. But it doesn't matter.


ONLY HAVE IT TESTED!

 

i'm sure if you take the time to reserch it a little more, you will find that the voltage regulator on our rigs is contained directly within the PCM.

 

Voltage regulator is in the alternator. There are many things the power rolls around other than the PCM. This voltage is regulated. Do a voltage test. Not to mention follow the wires.

If the voltage all went into the computer then how would your battery get charged with 14.3 Volts. It just can't happen. I think you need to do some research on this yourself.
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In older vehicles, this was a good idea to get you back on the road again. Not todays with high tech computers. I can see what you are talking about here, but you don't understand the whole picture.

 

LOL.
...Obviously flaw in that thinking...
The D won't run with a low battery worth a ****... simply try to get it to run without one at all.
Not calling you a noob but that was some bush league advise there man.

IndyD