Voltage drop

[AphexTwin 10+ year member]

Ok so my car has a factory voltage meter and it dips to around 13.5volts when ever im idle with the system cranking. If im on the move or the stereo is off its at 14.4 steady even at idle. Im running 2 amps right now both pushing 400 watts each. I recently received some subs and am going to power them with a 600 watt amp. so thats 1400watts total. Should i get a new alternator before i hook up my sub? 2001 GMC sierra factory one is rated at 105-130 amps or so i think. Ohh and ive already upgraded the big 3 with 1/0 guage wiring. I just noticed it this morning so i cant tell if the headlights are dimming yet.

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[ampresearch 10+ year member]

a new alt and battery or two would be a good idea. 3 amps depending on size and brand will pull alot of juice at full tilt. the average charging system will nto be able to keep up for long.

 

[POLKAT 10+ year member]

New alt for sure. Adding a battery is NOT going to help you while the car is idleing. All it is going to do is strain your factory alt even more.

 

[ultimate157 5,000+ posts]

Ok so my car has a factory voltage meter and it dips to around 13.5volts when ever im idle with the system cranking. If im on the move or the stereo is off its at 14.4 steady even at idle.

Usually a stock alternator will put out much less amps at idle vs higher engine speed. Since you arn't drawing much power at idle, with stereo off, its at 14.4v. This is normal. However once you start going up in your wattage/amperage draw with more amplifiers, you should look into upgrading your alt + battery.

 

[PollyCranopolis 10+ year member]

My 92' Honda Civic has an unsteady voltage rate. I just installed an 880PRS, which has a voltmeter that shows me volts on about a 5 second interval. Driving around town or at idle, the volts will drop to around 12 with the volume up. Interstate/fast cruising yields 13.6 to 14.1(mostly about 13.8). Never seen it above that even with the stereo off.. I've had this car wired for years and have yet to experience any electrical problems because of this, and only very slight dimming. Figure it would be a good idea to get the alt rewound to maybe around 120A, and get some BIG3 wiring regardless. Trying to figure out the specs on the stock alt. I figure 60-80, the latter being due to the fact the car has AC.