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DLW · 10-24-2017, 12:39 AM

I agree with PG.

I would add up all your heavy hitters that could be on at once and at idle.
Like fans, fuel pump, AC, headlights and stereo.
I would dig out the DMM and measure voltage at the battery and alt to figure out what alt you need. Most alternators amp rating are at the max rating and not at engine idle speeds. So a 105 amp alt may only put out 65 amps at idle (800 RPM), and 105 amps at like 1200 RPM. Just something to add to the equation.

10-24-2017, 12:39 AM	#4
DLW Registered User Join Date: Apr 2014 Location: Union City, CA Posts: 384	Re: too many amps, need better alt? I agree with PG. I would add up all your heavy hitters that could be on at once and at idle. Like fans, fuel pump, AC, headlights and stereo. I would dig out the DMM and measure voltage at the battery and alt to figure out what alt you need. Most alternators amp rating are at the max rating and not at engine idle speeds. So a 105 amp alt may only put out 65 amps at idle (800 RPM), and 105 amps at like 1200 RPM. Just something to add to the equation.