Stock Alternator

boomer8800 · March 27, 2002

Whats the output of a stock alternator on a new 02 Tahoe?

The GM site states 130, is that at idle, driving or what? I just added a 1000 & 300 watt amp and not sure if I needed to get a high output alt or just a 1.0-farad Capacitor ??

chevy4x4trucks · March 27, 2002

IMO, just give it some time. If you notice the headlights fading in and out when you use the power windows then it's time to step up to a higher output alternator. The 130 that's on the site sounds about right, I recall it either being 130 or 135.

LarryE might know a bit more, he's got more knowledge of stereo equipment so he may be able to lend you a hand.

y2kz71 · March 27, 2002

On the trucks its a 105amp or an option for a 130amp. If you write the number down of the drive belt and call an auto parts store they can tell you from that because the 130amp carries a longer belt due to the pulley diameter.

siume99 · March 27, 2002

BOOMER, I remember it being a 130A alternator. Now whether that's enough for what you want is another story.

Jon (Chevy4x4trucks) mentioned the dimming of the lights with the power windows. I notice a difference if I'm looking for it, but very minute.

gandolphxx · March 27, 2002

If you keep adding that kind of audio power you will want to consider a Powermate or NWWrangler upgrade - most of the 4x4 shops have them - apparently "roughers" liek their conveniences at the end of the day.

95Yukon · March 28, 2002

The 105 or 120 number is amps output at cruising rpms, or maximum output. Mine had a 105, which is actually a 70/105, which is, 70 amps at idle speed, 105 at cruising speed or higher rpms.

I replaced it with a "high output" alternator from truckperformance.com and those are direct replacements for the 70/105. It is advertised to have better windings and heavier-duty electronics and is rated at 80/120. It did come with a smaller pulley than stock which put my belt tensioner right at the end of its travel, so I had to get a belt that was about 1 1/2 inches shorter. The smaller pulley increases the speed of the alternator at idle, which I think has a lot to do with the higher amp rating, since it's always spinning a bit faster than it would with the factory, larger pulley at any given rpm.

I also replaced the 10 gauge charging wire with 6 gauge to be sure theres no added resistance there, as well as the battery to chassis ground wire. My electric fans pull 30 amps, and when the a/c is on, they run full time so it was time for an upgrade. Sortof off subject, Flex-a-lite is supposed to be coming out with a new control module which runs the fans at 60% speed for a/c duty, and full speed if it gets too warm, but it won't be for a few months, according to them. The volts tend to drop off a bit more than I like when at idle, in gear, with those fans on (and a/c clutch, and blower on High)

gandolphxx · March 28, 2002

If you are going to add an electric fan, you will definitely want to consider a heavier duty alternator and feed wires. Kill two birds with one stone. :music: