If you don't have one, I wouldn't rush out to get one if you could just take it to autozone or a parts store where they test batteries and alternators for free. Put the meter on DC V, put the red probe on the positive and the black probe on the negative on the battery with the car off and you want to see around 12V. Now turn on the car and do the same thing and it should read around 14V. That usually indicates that battery and alternator are good. It means the battery is holding a 12V charge without any assistance, if you will, and when you turn the car on, the alternator raises it to 14V. Another thing to check for is to see if the voltage is constant. When you're measuring and the voltage jumps up and down and it doesn't stay at a certain voltage, there's another issue behind it. I changed out a battery that was doing just that. It would read 12V but as soon as any load was applied to it, it would drop to 0V. Unfortunately you can't test that with a meter but the parts store should have that there. Like I said, if you can, just take it up there and have them test it for ya. It's free.
Originally Posted by FX4 Level II
