Charging system help

[jrh8tc]

Alright i just replaced the alternator in my car with a used OEM because my old one was having voltage regulator issues. Tonight i got in my car and started driving and realized the radio didnt come on when i started it and my dash lights seemed kind of dim. I parked teh car and it wouldnt quite start again the battery was about dead. Anyway im guessing its the alternator again, but i just wanted to make sure there was nothing else. After the car sat for a couple minutes I came back and it started and the radio came on with it but soon went off. Also, i still ahve the old alternator so I was considering putting the voltage regulator into it from this one now, I didnt know how big of a project it is to do something like that. Let me know what you guys think or if this alternator is bad already, I put it in 3 days ago.

Thanks,
Jeremy Hoefer

 

[brute]

I highly doubt it. Check your fuses.

 

[jrh8tc]

All the fuses are good. I dont know what the deal is, I just started it again and it will stay running but the radio will come on and then go off and everything is real dim. I turned on everything possible in the car and everythign got really really dim but the car will stay running for as long as needed. Its like the alternator is just pushing enough volts to keep it going. Could the battery be going bad to cause it to not hold enough of a charge or waht? The battery is new also. Any suggestions?

 

[brute]

Try charging the battery overnight. It may have enough charge to start the car, but not enough to power accessories and stuff. Overnight, it should charge up 100%.

 

[steve]

Alternator is bad or the 80A alternator fuse is blown.
Measure the voltage at the b+ stud and at the battery with the engine running.

Does the battery idiot light turn on during the light bulb test when you turn the ignition on?

Steve

 

[98gst14b]

You may have a bad battery, charge you batteries like he said^ then in the mornin or whenever load test the battery to see if its bad. Check the water levels in it too before you charge it (unless its a MF) Good luck

 

[jrh8tc]

No lights come on, like usually when the alternator goes out the car freaks out right, like lights coming on and things going nuts but I havent had any of that so Im thinking its the battery.

 

[steve]

No lights come on, like usually when the alternator goes out the car freaks out right, like lights coming on and things going nuts but I havent had any of that so Im thinking its the battery.

No what usually happens is the battery doesn't charge and once the voltage drops low enough from discharging the battery the radio display turns off and then the car dies.

Steve

 

[jrh8tc]

Thats what i thought also but it has been running for three days fine so wouldnt the battery drain a little quicker than 3 days or could it just be charging but very little voltage?

 

[steve]

If the voltage from the alternator is less than the battery voltage no charging happens.
Depending on how much you used the various accessories it could have taken 3 days to discharge your battery or it could have happend quicker.

Do you have a voltmeter? The fastest way to resolving the problem is to start measuring voltages.

Steve