electrical problem
Thread Starter
Racer
Joined: Mar 2007
Posts: 337
Likes: 1
From: dallas texas
electrical problem
before i go out and buy a new battery, or alternator... which im assuming it is one of the 2. i wanted to ask if anyone experienced the same problem. i have very low electrical power. when im idling, the guage will be reading about 12, then suddenly shoot all the way down, almost die and go back to normal. when i have the blinker on, the guage will fluctuate up and down with the speed of the blinker. when i have the a/c on, it will read at about 9. should i have my alternator tested? replace the battery? ive never seen this before. thanks for any input
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
If the alternator is defective, then the red battery symbol light on the dash should be lit. Also, unless you have unusually low idle rpm or a smaller diameter pulley on the damper to reduce drag, the alternator should be able to maintain 14.3 volts (dash voltmeter) cold which will drop to 13.3 volts alternator hot. Dash voltmeters are inaccurate and read low without the alternator charging, or engine not running. You might also have a discharged battery which you can tell by measuring the battery voltage under no load, engine off. 12.0 volts and lower, discharged, charge the battery up with a battery charger, don't expect the alternator to charge the battery up, you will shorten the life of the alternator and it takes hours to charge a battery up. 12.9 volts and higher, fully charged and linear inbetween. If you have a voltmeter, measure the voltage at the battery terminals engine idling and see if you have 13.3 - 14.7 volts. If lower than 13 volts, than take the alternator to a car parts place that can test it for you.
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
If the alternator is defective, then the red battery symbol light on the dash should be lit. Also, unless you have unusually low idle rpm or a smaller diameter pulley on the damper to reduce drag, the alternator should be able to maintain 14.3 volts (dash voltmeter) cold which will drop to 13.3 volts alternator hot. Dash voltmeters are inaccurate and read low without the alternator charging, or engine not running. You might also have a discharged battery which you can tell by measuring the battery voltage under no load, engine off. 12.0 volts and lower, discharged, charge the battery up with a battery charger, don't expect the alternator to charge the battery up, you will shorten the life of the alternator and it takes hours to charge a battery up. 12.9 volts and higher, fully charged and linear inbetween. If you have a voltmeter, measure the voltage at the battery terminals engine idling and see if you have 13.3 - 14.7 volts. If lower than 13 volts, than take the alternator to a car parts place that can test it for you.
And be sure to check for loose or corroded battery cables.
Racer
Joined: Jan 2006
Posts: 473
Likes: 7
From: Houston Texas
The Texas heat is a killer on alternators!
I used to go through the GM re manufactured ones every couple of years or so but when Hi-Lo auto parts was around they used to offer a lifetime warranty on it. Lucky for me!
A few years ago I purchased a high amp unit from Motor City Reman on eBay and it's lasted good so far. (knock on wood-summer is here!)
I've heard both good/bad about them but the one I have has been ok.
I did have to run a larger cable (fused) directly from the alt to battery and ran an extra ground straight from alt mount to battery.
The alternator place recommended this since the amp/output was much higher than stock.
Good luck! Let us know what you find.
I used to go through the GM re manufactured ones every couple of years or so but when Hi-Lo auto parts was around they used to offer a lifetime warranty on it. Lucky for me!
A few years ago I purchased a high amp unit from Motor City Reman on eBay and it's lasted good so far. (knock on wood-summer is here!)
I've heard both good/bad about them but the one I have has been ok.
I did have to run a larger cable (fused) directly from the alt to battery and ran an extra ground straight from alt mount to battery.
The alternator place recommended this since the amp/output was much higher than stock.
Good luck! Let us know what you find.
