Blackout67

Wanted to see possible ways to decrease voltage drop? I have upgraded to 2 gauge OFC wire from the alternator post (stock alt) to the PDC and PDC to battery, as well as added a 2 gauge OFC ground from the fender to the battery. Battery is fairly new. It's a Super Start AGM that I had gotten about 6ish months ago. At its best, at idle it puts out 13.8 at idle and maybe 14 volts reviving. But usually sits between 13.4-13.6 volts, testing post to post with DMM even while revving and I have two main theories:

When I go to start up the jeep almost every time it's started there is a loud squealing from what I assume is the belt. The longer it's been sitting the louder and longer it does it, although after about 3-5 seconds it usually stops
Or
I've heard that AGM batteries are very sensitive to heat and my engine bay gets pretty hot and stays hot several hours later, not to mention the upper rad rose sits like half an inch away from the top of the battery and I was thinking of maybe doing a rear battery relocation.

Any help is appreciated 🙂
(98 4.0 btw not sure if that matters)

Roler

13.8V with the engine on is normal for the XJ- mine has only been higher than that on cold mornings.
The voltage regulation is done by the PCM- there is no external voltage regulation.
The battery temp sensor (under your battery) feeds info to the PCM which influences the charging voltage the PCM dictates to the alternator.

The belt needs to be pretty snug on the XJ, try tightening it a bit. But the 13.8V wont be going up.
You run a lot of aftermarket accesories?

There is a hack with the battery temp sensor to splice in a resistor, making the PCM think the battery is cold and then increases the Alt Volts charging the battery. But once again: the 13.8V you see is normal for the XJ , that doesn't see the 14+ voltage charging other vehicles might have.

97grand4.0

Agreed what he said. Myself I did the regulator hack on my zj. I’m glad I did, charges consistently higher. So I’ve had the dodge truck external regulator in for anbout 4 years now. Unless you have the electrical background I wouldn’t recommend trying it tho.

Blackout67

I figured that I was within the nominal charging range, I just wanted to see if there was anything I could do to raise it up at all. I do have about 1600 watts RMS worth of amplifiers for my audio system and the key to actually reaching those numbers is a consistent 14.4v which the voltage the amps power is rated at. Just weird going from my 05 Sierra which reads a consistent 14.4v pretty much all the time

Blackout67

I'm sure it's not too hard. I'm not electrician but I've done a lot of electrical installation in 12v car systems so I could probably figure it out. I'll look into, thank you

97grand4.0

No it’s not hard at all I’m sure you could do it. There was a quirk I encountered, I can barely remember now, oh, …I think to do with the ..yes, I think it was the silly charge warning or check engine light or something wanting to come on . I found a way to get around it whatever it was, it was inconsequential to the actual charging, which was 14.3-4 . I think somehow the pcm is still monitoring the charging voltage and may set a warning. Whatever it was you’ll figure it out and it’s easy.
yeah for $15 for a dodge ram regulator, I love it. No problems with my system, zero.

Blackout67

Do you have a video with instructions? Can't find much about that fix

97grand4.0

Try Google.

https://www.jeepforum.com/threads/wr...371023&slide=0

97grand4.0

there is a diagram schematic about 3/4 the way down that’s good. I think they added the 20 ohm resistor, to make the pcm Think the alternator is connected. That’s what I couldn’t remember,