Voltage drops and sticks

[noble brown]

I noticed my voltage will drop, while driving, from 14+ to maybe 12+ and it will just stay there. When I first start driving and turn up the radio the voltage will behave as expected. It will drop but will come right back up. But after about 15 min or so it won't come back up. Even if I turn the bass all the way down it still won't bounce back. I have a stock alt, 130 I think and two wet cells. Is my alt going?

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[Savackz]

Take it to a o'reillys or something like that and get it tested. Also, what amp is it?

 

[MrFoca]

Go have the alternator tested. If it's not the alternator have the batteries load tested.

 

[noble brown]

I'll get it tested this weekend along with the batteries. Is this a common symptom of a alt going bad?

 

[MrFoca]

My old car when the alt was bad it would die after the battery was pulled down.

 

[ancorp 10+ year member]

Does it come back eventually after you turn it down? Sounds like your system is draining the batteries to the point that the alternator can't provide enough current to keep the voltage up. It's still charging most likely, and the voltage should slowly climb back up with time, unless you keep the music playing. What system are you running? What size and how old are the batteries?

 

[noble brown]

I turned the bass all the way down and turned the h/u down but not off. I waited maybe half a minute and there was no change. I will experiment more at lunch. At a fresh start up voltage is at 14.3 so I do believe it is still charging. The amp is a mtx81000 and it's running a 15" zcon at .5. Box rise puts it at about 1+. 1/0 wiring and grounds. Don't know about battery size. They are stock with my 07 Lucerne 3800 engine. They are about 2yrs old

 

[MrFoca]

I'd start simple man. Just get everything tested and go from that point. Just seems like once it's discharged a good amount of power it's having a hard time coming back to charge. Is it the OEM alternator ?

 

[los33]

Sounds more like a bad alternator regulator.

If not you have a very loose connection from your alternator that causes it to disconnect during movement.

Sent from my Z970 using Tapatalk

 

[joom 10+ year member]

I think you are experiencing normal behavior for alot of late model gm products. It's a way of eking a lititle more mpg out of them. Did you ever monitor voltage Guage closely before your system. I have a 2013 silverado and it does the same as did my 2012 malibu.

 

[noble brown]

Yeah it's OEM. And I can check my connections to be sure but pretty positive they are good.

No I never monitored voltage before. So I have no clue if this is normal or not. Thanks for the thoughts.

I'll start simple and work my way up.

 

[joom 10+ year member]

Do your headlights turn on automatically? If so there is a sensor on the dash that if covered will allow the lights to come on. This will usually make voltage come up. Try it. May show you where your issue truly is. The programming in the pcm.

 

[noble brown]

Yeah they do. So you're saying that the PCM may be regulating my voltage as needed. If I cover this sensor my voltage should pick up to meet the increased voltage demands of nighttime driving? I will try that. If I don't get a voltage rise what would that point to? Alt?

 

[los33]

Do your headlights turn on automatically? If so there is a sensor on the dash that if covered will allow the lights to come on. This will usually make voltage come up. Try it. May show you where your issue truly is. The programming in the pcm.

Yeah they do. So you're saying that the PCM may be regulating my voltage as needed. If I cover this sensor my voltage should pick up to meet the increased voltage demands of nighttime driving? I will try that. If I don't get a voltage rise what would that point to? Alt?

This does not affect voltage. The sensor is an ambient light sensor in most newer gm cars from 2000+.

It will dim your interior lights when headlights are on, but it does not affect voltage.

That is only in hondas.

Sent from my Z970 using Tapatalk

 

[noble brown]

Oh OK. Thanks for the clarification