Do I need a HO Alternator?

[rpr]

I have low voltage issues at idle on my 2014 Ram Laramie Limited with a 5.7L Hemi. The vehicle always seemed to idle low. The dash gauge (which I don’t assume is very accurate) reads around 600rpms at idle. Since idle speed is computer controlled I doubt that’s the issue, and I’m thinking my alternator may need to be upgraded. I don’t have any crazy accessories on the truck, but I do have two amps that total 1,300 amps RMS at 4 ohms. Would that typically be enough to warrant the need for a high output alternator?

I also have HID headlights, not sure if that would create an additional strain.

 

[Nick@GotExhaust]

600 rpm is pretty normal. What is the actual issue you have? Is it the fact that you think it idles low or do you have dimming lights or something?

HIDs if quality ones, actually draw less power than the halogens they replace so no problem there. 1300 watt stereo probably isnt enough to really cause an issue, at least not a constant steady one. I've ran 2000w in the past vehicles and not had an issue. First thing I would do is the BIG 3 upgrade.

One aspect that is often overlooked when installing a high power mobile audio system is the current capacity of the factory wiring. The wiring put in place by automakers is just sufficient enough to support the current demands of the factory accessories and is rarely able to support much more than that. A fairly simple and inexpensive way to address this is to replace or augment the factory wiring with new, larger gauge wire. This will help greatly to support the extra current draw that a mobile audio system will demand. The “Big 3” name is because we will be upgrading three key wires in the vehicle. Here are the wires you need to upgrade:

1. Ground wire from battery to frame:
   Use at least a 4 AWG wire and place it directly under the factory ground strap that runs from the negative battery post to the frame of the vehicle. Grind away any extra paint on the frame to bare metal to allow the new, larger ring terminal to make full contact with the frame.
2. Ground wire from engine to frame:
   This will be almost the same as the “battery-to-frame” upgrade. Use at least a 4 AWG wire and place it directly under the ground strap that runs from the engine block to the frame. Grind away any extra paint on the frame down to bare metal to allow the new, larger ring terminal to make full contact with the frame. In some vehicles there may be a ground strap that runs from the alternator casing to the frame. It would be a good idea to upgrade this also if your vehicle has this.
3. Power wire from alternator to battery: Use at least a 4 AWG wire and place it under the factory ring terminal on the power stud that is on the side of the factory alternator. Run this wire to the positive battery post and be cautious not to route it where it will contact hot engine components or moving parts such as auxiliary belts. Fusing this wire near the alternator is a good idea as well for added protection in case it gets damaged. This will blow the fuse and still allow the factory system to continue to operate.

The “Big 3” upgrade can not only improve the performance of your audio system, it can also enhance the performance of the entire electrical system for your vehicle (which can lead to improved fuel economy or additional horsepower). In other words, upgrading the “Big 3” is almost always a good idea.

Note: For systems that will exceed 1500 watts (of actual power) it would be best to use larger wire for the upgrade such as 2 AWG or Ø (1/Ø) AWG. This much power may also require an upgraded alternator.

A quick note about wires:​

There are many companies offering wire that is a combination of copper and aluminum. Aluminum is not as conductive as copper. Aluminum is also less expensive than copper, so when comparing pricing and wire size it can be a bit misleading. You should only consider using true copper wiring, but if you want to consider the copper/aluminum wire, it is best to look at a wire size that is 2 AWG larger (smaller number) to ensure safety and proper conductivity.

 

[rpr]

Nick, thanks, I posted in a hurry and meant to mention the issues I’m having. The lights dim when I turn the wheel even slightly at idle. That doesn’t worry me too much though. The bigger issue is that if I try to charge a device besides a cell phone (using either the 12V USB ports or the 120V receptacle) it stops charging when I idle. As soon as the rpms go up it will start charging again. So this would seem to signify a low voltage condition at idle (I think).

The wiring to the amps is very large gauge pure copper. Agree on the Big 3, that is something I need to do regardless.

 

[Nick@GotExhaust]

I wonder if the regulator on your alternator is failing. I would go to a local autozone or advanceauto or anywhere like that and have them do a load test on your alternator.

 

[rpr]

What’s the consensus on the best place to get a pure copper Big 3 kit? I tried searching but didn’t really find any recommendations on the forum, which I thought was strange (unless I’m doing something wrong).

 

[RobertMcColl]

What’s the consensus on the best place to get a pure copper Big 3 kit? I tried searching but didn’t really find any recommendations on the forum, which I thought was strange (unless I’m doing something wrong).

Go onto a car audio supply. They have them. Check out www.skyhighcaraudio.com. They do big 3 kits with lugs already on and good to go. They run $70 for a 1/0 OFC. That is all you need for big 3 upgrade. Make sure you go OFC. Couple extra bucks but way better then CCA. I have that exact one in ky truck and am running 3000 watts RMS. I di have a HO alternator but would be pointless with out big 3.

 

[rpr]

Thanks

 

[WY-Dave]

Get you one of something like this, it will tell you what you are actually seeing.

Remember the battery is for starting and the alternator is for when running. Unless the draw is more than what alternator can handle, then it will grab it from the battery. The "average" alternator output is about 13.3 to 14.7vdc. if you get a way to measure the voltage, you can disconnect the neg battery and this way you can measure the pure output of the alternator. You can pre-loosen neg terminal for ease so you won't have t loosen on a running engine. Another way, is to disconnect the neg battery and use a jump pack or another vehicle to start it. Just remember to take the neg cable from the jump source and connect it to a ground and not the battery (just like jumping a dead battery).




Depending on the the efficiency of the audio amps, battery amp draw varies. Give out the Brand/model number and could look up what the rated draw is. Also the spec'd amp draw numbers are on a good thump or steady bass not consistent.