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No Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Tue, 14 Dec 2004 19:15:47 In Reply to: Is my alt. putting out enough juice?, JJ, Tue, 14 Dec 2004 14:10:19 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Once the voltage drops below 12.6, you're running your car on the battery. When the engine is running, the alternator should provide all the power necessary to both run the car AND charge the battery.
Under some conditions, it's OK to be running off the battery - that would be for very short times (like a minute or two) at idle. You are hopefully running in the 13.x range when driving around. If you spend much time below 13 volts, the battery isn't charging - remember, the battery needs to be recharged to deal with the power of starting.
One thing to know is that the voltage regulator is temperature compensated. The warmer it is under the hood, the lower the voltage will be - that's because a battery can't take charge as fast when it's hot. I don't know where you live, and how hot it is. I can see 12.6 volts as being reasonable if it's hot under the hood AND hot outside - like 80 or 90 degrees F. If it's cold, like 40 F or less, the voltage should be much higher, like high 13 volts.
Three things to do. First, under load, stick a digital voltmeter on the battery, and compare it to your dash meter. I don't know where you did the hookup for your meter, but due to load points between the battery and your meter pick-off, you may be reading wrong. Just a good thing to check.
Second - Check the alternator ground. A bad ground will drop your voltage.
Third - if the meter is correct, replace the voltage regulator. The brushes are built into the VR, and the brushes wear. If they get too short, you get poor contact, and one sign is the voltage dropping. So replace it. If it turns out that your alternator is just too small for the load and you put in a larger capacity alternator, pull out your new VR and stick the old one into the core. It never hurts to have a spare VR.
posted by 12.76.128...
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