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Strange voltage drop, alternator or something else?


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On 9/30/2022 at 6:17 AM, audiofanaticz said:

That is normal, nothing out of the ordinary. 
The problem is you're just learning how your car operates now after installing additional electrical things and not before so you think there is a problem when there is not.
Your car has the same 3.6L VVT 305HP engine as my 09 Cadillac minus the flexfuel sensor that I don't have.
These alternators are PCM controlled by the car, so when the additional amperage draw is not needed from the alternator the car essentially turns the alternator off to offer better fuel economy.
When the vehicle is started you will see the high voltage until the battery replenishes its charge basically then it will turn the alt off and be in the low 12's. Since you have an LTZ model Im sure you have heated seats, so next time your in your car driving in the day time and you see the voltage drop down to the 12s turn on both your front heated seats, rear defroster, headlights, even your heat/ac and once your car senses that additional draw on the electrical system it will turn that alternator on almost instantly bringing the voltage back up to the 14's.

The problem is your power wire is an additional add on and it's not being monitored through the cars computer so it doesn't sense the amperage load being used by your amp so it doesn't tell the alternator to wake up and work until the battery voltage drops below a certain setpoint that is programmed in the cars computer. 

There's ways around this but I'm not sure what's best since I never put a system in my car because I have my stereo truck, but this is common in a lot of newer 2000 and up vehicles from many manufactures!

It's not the power wire that senses the amperage It's the ground wire and I'm sure he didn't run the ground threw the rvc (regulated voltage control) sensor if you have a second battery your supposed the run power and ground from the front battery all the way to the back

06 Charger

Pioneer double din

Pioneer 6.5 and 6×9's

Knukoncept Krystal kable rca's

0 ga knukoncept kolossus wire 

Big 3 same wire ^ 1 run 

8g karma ss speaker wire

Sundown sia 3500d at 1ohm

2 Sundown U series 12's

Duralast platinum agm H7 (Main)

Xs power d3400

Trying to find a ho alt

 

 

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23 hours ago, Never Enough Bass said:

It's not the power wire that senses the amperage It's the ground wire and I'm sure he didn't run the ground threw the rvc (regulated voltage control) sensor if you have a second battery your supposed the run power and ground from the front battery all the way to the back

The word power does not dictate positive or negative

 

 

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Awesome thanks for the help man 👍 never knew the importance of that sensor and it explains a lot of my problems I have been having. 

 

I watched this video and learned a ton too

https://youtu.be/OqylgRKiC-A

 

How would I go about fixing this? I have not done any big 3 upgrades. I don't want to have to crank my AC all the way up every time I play my system. I could just unplug the sensor and live with the dash light but that's not a professional solution. Would I have to run another ground to the back to my amp through the sensor? Or maybe a acc battery in the back and run a ground through the sensor to that? 

 

I do plan on doing the big 3 soon, and if needed to get this sensor problem fixed I will do it. 

 

I know no matter what I'm going to get voltage drop, but voltage drop below 12v 😷 sounds like a bad idea. 

 

On 9/30/2022 at 5:17 AM, audiofanaticz said:

That is normal, nothing out of the ordinary. 
The problem is you're just learning how your car operates now after installing additional electrical things and not before so you think there is a problem when there is not.
Your car has the same 3.6L VVT 305HP engine as my 09 Cadillac minus the flexfuel sensor that I don't have.
These alternators are PCM controlled by the car, so when the additional amperage draw is not needed from the alternator the car essentially turns the alternator off to offer better fuel economy.
When the vehicle is started you will see the high voltage until the battery replenishes its charge basically then it will turn the alt off and be in the low 12's. Since you have an LTZ model Im sure you have heated seats, so next time your in your car driving in the day time and you see the voltage drop down to the 12s turn on both your front heated seats, rear defroster, headlights, even your heat/ac and once your car senses that additional draw on the electrical system it will turn that alternator on almost instantly bringing the voltage back up to the 14's.

The problem is your power wire is an additional add on and it's not being monitored through the cars computer so it doesn't sense the amperage load being used by your amp so it doesn't tell the alternator to wake up and work until the battery voltage drops below a certain setpoint that is programmed in the cars computer. 

There's ways around this but I'm not sure what's best since I never put a system in my car because I have my stereo truck, but this is common in a lot of newer 2000 and up vehicles from many manufactures!

 

On 10/2/2022 at 3:00 AM, audiofanaticz said:

 

 

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16 hours ago, audiofanaticz said:

The word power does not dictate positive or negative

No but the rvc (regulated voltage control) sensor does and the ecm that's connected to it does which reads the amps running threw it (only the ground wires go threw it)

06 Charger

Pioneer double din

Pioneer 6.5 and 6×9's

Knukoncept Krystal kable rca's

0 ga knukoncept kolossus wire 

Big 3 same wire ^ 1 run 

8g karma ss speaker wire

Sundown sia 3500d at 1ohm

2 Sundown U series 12's

Duralast platinum agm H7 (Main)

Xs power d3400

Trying to find a ho alt

 

 

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8 hours ago, LilFeels said:

Awesome thanks for the help man 👍 never knew the importance of that sensor and it explains a lot of my problems I have been having. 

 

I watched this video and learned a ton too

https://youtu.be/OqylgRKiC-A

 

How would I go about fixing this? I have not done any big 3 upgrades. I don't want to have to crank my AC all the way up every time I play my system. I could just unplug the sensor and live with the dash light but that's not a professional solution. Would I have to run another ground to the back to my amp through the sensor? Or maybe a acc battery in the back and run a ground through the sensor to that? 

 

I do plan on doing the big 3 soon, and if needed to get this sensor problem fixed I will do it. 

 

I know no matter what I'm going to get voltage drop, but voltage drop below 12v 😷 sounds like a bad I 

Upgrade battery + to alt + upgrade battery - threw rvc sensor (can fit 1/0) to alt bolt, run + and - from front battery to back battery if u unplug the pigtail mechman makes a bypass which will turn off the battery light 

06 Charger

Pioneer double din

Pioneer 6.5 and 6×9's

Knukoncept Krystal kable rca's

0 ga knukoncept kolossus wire 

Big 3 same wire ^ 1 run 

8g karma ss speaker wire

Sundown sia 3500d at 1ohm

2 Sundown U series 12's

Duralast platinum agm H7 (Main)

Xs power d3400

Trying to find a ho alt

 

 

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5 hours ago, Never Enough Bass said:

No but the rvc (regulated voltage control) sensor does and the ecm that's connected to it does which reads the amps running threw it (only the ground wires go threw it)

It measures current, positive or negative current is going to be the same result. If your pulling for instance 50 amps on a positive wire you will also be pulling 50 amps on the negative wire. That sensor does not monitor if it is positive or negative current. They chose to use the ground wire for simplicity of doing it in such they can monitor 1 wire and monitor the entire electrical draw of the vehicle because anything and everything is going to feed off of a chassis ground at one point or another. Where as the positive wire is snaked through the entire car that splits off to so many other electronic items. So many 2001 up vehicles have 3-6 different positive wires coming off the battery but only 1 ground, that is why the negative terminal is monitored.
So if that clamp sensor was large enough to fit around all the main positive wires and you swapped it to positive (even though it was monitoring negative) the car would have no idea what you did and would function normally.
Current is current, it doesn't make a difference if its positive or negative when measuring current.

 

 

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13 hours ago, LilFeels said:

How would I go about fixing this? I have not done any big 3 upgrades. I don't want to have to crank my AC all the way up every time I play my system. I could just unplug the sensor and live with the dash light but that's not a professional solution. Would I have to run another ground to the back to my amp through the sensor? Or maybe a acc battery in the back and run a ground through the sensor to that? 

 

I do plan on doing the big 3 soon, and if needed to get this sensor problem fixed I will do it. 

 

I know no matter what I'm going to get voltage drop, but voltage drop below 12v 😷 sounds like a bad idea. 

 

 

 


The turning your ac, heated seats, etc on was just so you can put load on the electrical system and visually see that your car is fine and normal and that once the system notices that load then it turns on and charges at normal voltages because you think its broken when its not. You just never paid attention to it until recently doing things in your vehicle and are now freaking out about it because you think you messed something up.

Also its worth mentioning that upgrading the wire size through it is not needed in his case for a 1000wrms amp.
The fact that the amp is grounded through the chassis and not on the batteries negative terminal (before the sensor), than that sensor will be measuring the current demand of the amplifier as well.. 

That 50 watts of amplifier power you'll be missing because its at 12.3 volts instead of 14 will not even be noticeable to you, and not really something I would concern myself with unless you upgrade to a larger amp thats 2000-2500 watts. 

If you want to do anything upgrade the factory battery to an XS Power battery which will hold a slightly higher voltage over a stock battery and also be able to discharge more current, but even then I don't see it being worth it for such a small system.

The factory positive and negative wire from the alt are rather short and due to that can easily and safely handle the current demand of that amplifier.
Your biggest hinder is going to be using quality OFC wire and not CCA wire, as well as a quality grounding location that is mounted with a bolt/nut and paint scrapped away for a solid metal on metal contact.
 

 

 

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  • 4 weeks later...
On 10/4/2022 at 6:23 AM, audiofanaticz said:


The turning your ac, heated seats, etc on was just so you can put load on the electrical system and visually see that your car is fine and normal and that once the system notices that load then it turns on and charges at normal voltages because you think its broken when its not. You just never paid attention to it until recently doing things in your vehicle and are now freaking out about it because you think you messed something up.

Also its worth mentioning that upgrading the wire size through it is not needed in his case for a 1000wrms amp.
The fact that the amp is grounded through the chassis and not on the batteries negative terminal (before the sensor), than that sensor will be measuring the current demand of the amplifier as well.. 

That 50 watts of amplifier power you'll be missing because its at 12.3 volts instead of 14 will not even be noticeable to you, and not really something I would concern myself with unless you upgrade to a larger amp thats 2000-2500 watts. 

If you want to do anything upgrade the factory battery to an XS Power battery which will hold a slightly higher voltage over a stock battery and also be able to discharge more current, but even then I don't see it being worth it for such a small system.

The factory positive and negative wire from the alt are rather short and due to that can easily and safely handle the current demand of that amplifier.
Your biggest hinder is going to be using quality OFC wire and not CCA wire, as well as a quality grounding location that is mounted with a bolt/nut and paint scrapped away for a solid metal on metal contact.
 

 

I have a 4 gauge power coming from up front, XS battery. And a 1/0 ground in the back going to bare metal (D4S wire on ground) with a nut and bolt and high quality terminations. All wire is OFC. When I don't have my AC blasting my voltages idle at 12.3v. when I play my system I will get voltage drop all the way down to like 11.3v. After making this thread I upgraded the ground, and it changed nothing. 

 

What is causing this voltage drop do you think? 

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The reason was already said...

Your alternator is controlled by the vehicles computer.

The alternator is designed to turn off until a large enough load is presented on the alternator (such as but not limited too having your heated seats, hvac, etc turned on).

So when the electrical demand is not sensed by the vehicle the alternator will turn off full and not charge until your voltage gets low (in the mid 11 volt range), if voltage drops below the setpoint for an extended period of time the alternator will turn on and start charging again.
So ideally you need to run your amps ground wire through the clamp meter that measures the current under the hood, which is not a for sure fix because the computer is programed to control the alternator a certain way, and the problem with bass is its not a constant consistent demand, it has peaks and valleys, or ripples of current so running the ground wire through the clamp might not even do anything because its not a constant consistent voltage/amperage draw like other high power use things are such as heated seats or hvac, etc.

You will most likely need to bypass the the pcm to have your alternator charging all the time, which will most likely through a battery light on the dash.
Some alt companies make harnesses to bypass the pcm control and the harness will turn off the idiot light too, so your best be would be to start calling/emailing places like Mechman, Singer Alternators, US Alternators, Brand X Electrical, Dc Power Engineering, Custom Electric Service, JS Alternator, to see if anyone offers a harness that can do just that, or if they can build you an aftermarket alt to fix this issue.

 

 

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