I've seen a couple on here have done it, but with no real good direction to which one should be used. I have a moderate audio system installed. I'd like to get the load out of the PCM and use an external voltage regulator. I need to tear into this thing for a good week or so to do some engine work, struts, brakes, ect. The alternator is getting replaced so I want this to be done at the same time.
I don't need step by step directions, just a general point into what external regulator should be used.
do i live under a rock? why do you need a voltage regulator? if you're worried that the system is hogging too much power, get a bigger alternator, add another battery, get a bigger capacitor, or any combination of the three.
what do you mean by moderate? mine is just over 400w rms and everything under the hood is stock and only have a 1/2 farad capacitor.
Because it is my understanding that the factory regulator is built into the PCM. And if you constantly push it hard you run the chance of burning that up. And I'm already looking into replacing with a slightly larger alternator, adding or up-sizing power and grounds, better battery.
I just want a reliable, constant voltage from the alternator. The factory regulator, even with subs off, doesn't seem to do that.
Because it is my understanding that the factory regulator is built into the PCM. And if you constantly push it hard you run the chance of burning that up.
for every 500w rms you need at least 1/2 farad of capacitance. as long as you're not using the an output from the PCM to power your subs(you'd be a complete idiot to try, and i promise it wouldn't last 5 seconds) you're fine, the two systems are independent of each other. if your voltage at the battery drops below 12.5 volts while the amp is on, get a bigger alternator or a smaller sound system.
there's a reason people who run huge systems have multiple alternators.
Its not a huge system. A 500w Rockford amp with 2 12" subs. The amp is just a little undersized so I push it near the limit a lot. I know I need a better battery.
My lights dim whenever I do anything in the car. I hit the brakes and flip the turn signal on and they go dim, bright, dim, bright. Same if I roll a window up or down or have the rear defrost on, ect. The current alternator charges fine, cables are excellent, and the battery reads about 13.4 to 13.7 while running with nothing else on, and a little over 12 after being off for a couple days. So, unless there is something else I'm overlooking...
Also, shouldn't I be able to run around 14.3 volts? I know that little bump can make a huge difference. I used to change regulators out on my Fords to get higher charge voltage.
Its not a huge system. A 500w Rockford amp with 2 12" subs. The amp is just a little undersized so I push it near the limit a lot. I know I need a better battery.
My lights dim whenever I do anything in the car. I hit the brakes and flip the turn signal on and they go dim, bright, dim, bright. Same if I roll a window up or down or have the rear defrost on, ect. The current alternator charges fine, cables are excellent, and the battery reads about 13.4 to 13.7 while running with nothing else on, and a little over 12 after being off for a couple days. So, unless there is something else I'm overlooking...
Also, shouldn't I be able to run around 14.3 volts? I know that little bump can make a huge difference. I used to change regulators out on my Fords to get higher charge voltage.
im a little curious of the amp... does it say 500 on the top of it? perhaps with a red light under it? is the supposed 500w rms or peak?
rockford fosgate is well known for producing high quality amps that produce more power than they are rated for. example, my amp is an RF P500-2, however on the test sheet it says that my particular amp when tested from the factory cranked out 742w rms when it is only rated at 500.
I found the section in the FSM(sect. 8F-17) that talks about how battery charging works in our cars very informative. The PCM looks at a few sensors, calculates some things and tries to keep battery voltage between 13.5 and 14.7. I also read that if the PCM doesn't see one of the key inputs it looks for in the charging system that it will set a DTC.
I'm going to grab one of those AGM Duralast batts from Autozone here soon. My current batt is some cheap crap 500ca. Its got some leakage, but still shows good numbers after sitting.
I don't have a capacitor for my system yet. The audio wasn't priority here, just keeping charging consistent. I do plan on one here soon. But, I did find my high cooling fan is locked up. So I'd assume it would be causing some high current draw when it tries to turn on.
I found I can use a Transpo C8313 adjustable regulator and wire it in fairly easy. And already planned the "Big 3", as some call it. I just want to eliminate the lower voltages when something is on. I know bumping the voltage .5 to 1 volt will help me. I'm not new to electrical, just to Chrysler's set-up.
All grounds and wires look great. I replaced the positive terminal a while ago with a larger, brass audio one. I also realize the current alternator could just be going bad without making noise, heating up, or not charging.
I like how your complain about dimming lights and everything, then you finally come out and tell us that you have a crap battery, leaking at that. 500ca is not much now and days as well. You haven't done the big three upgrades.
No wonder your lights are dimming. I have a Red Top Optima, Upgraded Grounds, a 200watt RMS Class D mono Amp pushing a 12, and a 40x4 rms EQ amp pushing 6 speakers, and at night with fogs and headlights on, my fans can kick on and my lights will not dim while listening to music. And the biggest part, I only have a 90 amp Alternator.
By the way, you can overcharge a battery btw. Having the proper equipment, done right, you shouldn't have charging issues.
I have the RF-P500-2, too. And its set up with 2 channel, 2ohms. Have a couple nice Orion 12" subs. Its an older model of their current dual 12" subs in a box. I ran 2ga wire to the amp(its what I had already). They seem to work great together. The amp stays cool to the touch, and it rattles my rear view mirror off.
As I've already stated, I was just asking about which external voltage regulator I should use. I wanted the higher, consistent voltage.
I like how your complain about dimming lights and everything, then you finally come out and tell us that you have a crap battery, leaking at that. 500ca is not much now and days as well. You haven't done the big three upgrades.
My battery does have some sign of previous leaking. A positive terminal turned to dust will do that. Its been washed and no more has been seen. Voltages still show great after sitting a few days. Yeah, its a bit small anyways. By the way, I have not done the big 3 yet btw.
Anymore info on this? What size diode would I need?
I'm looking at a 130amp alternator, which isn't that much bigger. Also a new battery and bigger/more grounds. I realize the dimming has nothing to do with the peak voltage output. But I still want to have peak voltage output. Its better for performance, lighting, and my subs.
i think if you just get a bigger battery, a 1 farad capacitor and use appropriate sized power wires for the amp with a good ground you'll be just fine. the battery is holding you back and that amp is sucking more power than you think. it hits hard. at its lowest setting its over 30 amps.
would highly recommend the 130amp alt. if you only have a 90amp in there now.
my opinion on trying to manipulate the alternator output prior to upgrading some of your equipment, is that it is a waste of time. i think your low output and fluctuating voltage is a symptom of having too much draw and/or not a strong enough charging and storage system.
I'll chime in here; last year I had a similar goal - to raise the system voltage using a little trick.
For whatever reason, Chrysler decided on a really low voltage, 13.5 - 14.0, most of the time being 13.6ish on my car. At this voltage, lead acid batts need hours to reach full charge, driving around town this won't happen. My batt voltage drops to 12.0v after sitting only 3 days, this is BAD for battery life. Anything below 12.5v sulphation starts.
Since the voltage sensing is build into the PCM, the only way to raise voltage is to "trick" the computer into thinking voltage is lower than it actually is. The solution? A diode.
A typical diode drops voltage by around .6 - .7v. Take out the PCM fuse (I think #23), it's the 10amp fuse, on the driver's end of the fuse block, should be the middle of 5 fuses. Put the diode in their, make sure direction flows from driver to passenger. If you mess up the direction engine won't start, simply flip it around.
I used two schottky diodes, each with around .3v drop. My car now sits around 14.3v, spiking 14.6v in cold weather. This is perfectly fine, as in cold weather lead acids NEED more voltage to receive a charge. I've seen modern GM trucks measure close to 15.0v in the cold, so we're perfectly safe.
Of course, this won't fix your problem if your alternator is undersized. But my police package has 160amp stock so I'm happy
...Since the voltage sensing is build into the PCM, the only way to raise voltage is to "trick" the computer into thinking voltage is lower than it actually is. The solution? A diode...
Yes - that's what I was proposing. I wasn't sure which power input to the PCM would be the correct one since there is more than one - so thanks for answering that. And apparently there's not a huge amount of current on that wire requiring a large (high current) diode. Did you happen to measure the current? Do you know the current rating of the diode you used (or it's part number)?
I don't have access to my FSM's at the moment, but there are 2 fused sources of power to the PCM (It might be 3, but I think it's 2) - so the diode needs to go into the correct one (or a diode could be put in both).
Hello I have a 2004 300M with 2.7l engine.
My battery charging voltage was low every time, max 13.6V - too low for my 14.4V battery to Charge it full.
So I made this modification and replaced the PCM and the ASD/PCM fuse with a schottky 10A diode, the charging voltage rised to 14.4V by running parked - perfect!
But...
While driving 10 minutes the battery light came on and the voltage dropped to 10.8V. Too low. (headlight, ac and rear defroster was on 10 mins at this time too).
So this mod is making troubles for me. What could be the problem? Maybe too high charging voltage now?
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