View Full Version : Testing an alternator??
10-11-2002, 12:26 PM
What's the procedure, and what equipment do I need to test my alternator??
I don't want to just test voltage, I want to test the amperage or alternator output. I already have a digital volt meter.
If a Volt Meter is able to measure the DC current, what does it mean when it says:
"DC current - 200ÂµA, 2000ÂµA, 20A, 200mA, 10A"??
Isn't this WAY too low? I mean is it saying that it can only test UP to 10 amps??
Why not just go to Autozone? it's free.
10-11-2002, 12:42 PM
I don't believe it's practical to load test your own alt. When the auto parts store tests them, they attach them to a machine that has a motor and ammeter & voltmeter. I don't know at what current they test them, but you'd require a pretty good size resistor for load testing.
Yes, 10A is the max your multimeter will go to, most don't measure very high current, mine maxes out at 20A.
10-11-2002, 01:23 PM
I need to test the output of mine..
I'm gonna hook my digital multimeter to a cigarette lighter plug and see what voltage it actually is charging at. When the motor is cool it's above 13, when it's warm, it's always under 13.. So i'm getting kinda suspicious about it. Plus, the whine I hear under the hood sounds like I have a damn S/C, lol
I just use my DIC, it's usually 11volts before I start the car, around 13 volts at idle, and 14.4 above 2000 rpms.
10-13-2002, 02:23 PM
To accuratly test an alternator you should put in on a scope. This tests volts, and amps with and without load.
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