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Strange voltage drop, alternator or something else?


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2016 Chevy Impala LTZ 3.6L 

2 12" Sundown E V4 1000W RMS

D4S JP8 @ 1ohm

For the past month or two I have been getting some strange voltage drops, it has been occuring right after I installed a starlight kit in my headliner. I put this on a relay, but I have disconnected it since the problem has started.

 

The Problem

When I first start the car, it goes from 12.3-6 all the way up to 14.... Normal. 

 

But once I start driving it almost immediately dips to 12.3. This 12.3 voltage is what it almost always sticks to. I have a meter on my amp knob, as well as one built into my dash and both read the same. 

 

This problem occurs even if the fuse is taken from my main amp power wire. Even if no voltage is running to the amp, I still get a voltage drop. 

 

A week ago I got and installed a brand new XS D series battery, I got the idea it might be a battery charging thing so I have it on a charger right now, and going to update the thread in the morning. 

 

I am not sure if this is an alternator problem, just since it charges to 14v fine when I first turn the car on. 

 

Misc info:

4awg wire ran to subs, ground wire isn't the best so have upgrades coming now. Planning to do a big 3 soon.

Stock alt is 150a.

Problem occurs even if amp is disconnected. 

 

Any insight would be greatly appreciated 👍 don't want to order a new high output alternator if it's not necessary. Thanks SMD fam 🦾

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2016 Chevy Impala LTZ 3.6L 

2 12" Sundown E V4 1000W RMS

D4S JP8 @ 1ohm

 

For the past month or two I have been getting some strange voltage drops, it has been occuring right after I installed a starlight kit in my headliner. I put this on a relay, but I have disconnected it since the problem has started.

 

The Problem

When I first start the car, it goes from 12.3-6 all the way up to 14.... Normal. 

 

But once I start driving it almost immediately dips to 12.3. This 12.3 voltage is what it almost always sticks to. I have a meter on my amp knob, as well as one built into my dash and both read the same. 

 

This problem occurs even if the fuse is taken from my main amp power wire. Even if no voltage is running to the amp, I still get a voltage drop. 

 

A week ago I got and installed a brand new XS D series battery, I got the idea it might be a battery charging thing so I have it on a charger right now, and going to update the thread in the morning. 

Edit: charged battery up and now sits at 13.8v instead of 12.3, so seems like my primary problem was just a low battery 🙄.

 

 

I am not sure if this is an alternator problem, just since it charges to 14v fine when I first turn the car on. 

 

Misc info:

4awg wire ran to subs, ground wire isn't the best so have upgrades coming now. Planning to do a big 3 soon.

Stock alt is 150a.

Problem occurs even if amp is disconnected. 

 

Any insight would be greatly appreciated 👍 don't want to order a new high output alternator if it's not necessary. Thanks SMD fam 🦾

20220929_114414.jpg

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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!

 

 

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If u want higher voltage unplug the alternator you will have a battery light on tho I believe mechman sells a piece to fix the battery light hope this helps. I have a 2017 equinox that does the same thing it's a voltage regulator and when you do your big 3 make sure your ground wire goes threw the rvc sensor

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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It might be you need a higher output alternator this happened to me in my 2014 malibu it really all depends on two things A. How many amps you are pushing with your system and how many amps you car is drawing when driveing then you add both of those up and see if it's more then your alt can take and just because the car starts at 14v when fired up and then drops to 12v dosent mean you Baterry is fully charged mine currently runs around 13.8v when driveing 

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No it's a new chevy thing is your ground wire going threw the ground sensor and if u unplug the pigtail it'll charge at 14 or whatever but you will have a battery light on

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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The ecm will drop charge to save on gas or whatever when the battery is charged

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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1 hour ago, Never Enough Bass said:

No it's a new chevy thing is your ground wire going threw the ground sensor and if u unplug the pigtail it'll charge at 14 or whatever but you will have a battery light on

That's strange I haven't ever thought of what that ground sensor does. So that ground sensor is basically limiting the alternator when it senses the battery is fully charged? Thanks for the feedback buddy, appreciate it will do more research on it.

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1 hour ago, LilFeels said:

That's strange I haven't ever thought of what that ground sensor does. So that ground sensor is basically limiting the alternator when it senses the battery is fully charged? Thanks for the feedback buddy, appreciate it will do more research on it.

Yea I'm still researching it to sometimes I charge at 12.4 if you figure anything out about it let me know

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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