Battery, Alternator Headlight Issue?

[Irock1985]

Ok guys I have a weird one.... Yesterday I went to get in my car and it wouldn't start. Mind you I never had any indication my battery was on its way out. AS/S and remote start we're working just fine until the day before yesterday. Battery was reading 11.3 I think. So I drove down to Walmart bought a new battery and voila everything is working but....

Here's the weird thing. I noticed that my battery voltage is staying pretty low when actually driving. It's hovering around 12.5 and occasionally will bump up to 13 something. But I know it used to hover around 14.2-3 when driving around. Even stranger to me is that if I turn my headlights on it seems to kick in the alternator and jump up to 13.7-8.

So is this normal? Is it not charging because the battery is brand new and might not need the charge or is something wrong here?

 

[JoeBlog]

I understand that when you swap an AGM battery, you've got to tell the Battery Energy Management System it's got a new battery or it will continue to charge the new battery at the old rate. Smarter people than me on here may weigh in to correct or clarify that. I asked the owner of a battery shop about them, and they told me that AGM batteries have a circuit that communicates with the car, and it needs to be "introduced" to the car in order to work as designed.

 

[DrFaustus]

My diesel VWs have had AGM batteries and had no such requirement when changing batteries. And I had the software to do it if it was needed. That's the first time I have ever heard someone say that about charging one.

 

[Irock1985]

I understand that when you swap an AGM battery, you've got to tell the Battery Energy Management System it's got a new battery or it will continue to charge the new battery at the old rate. Smarter people than me on here may weigh in to correct or clarify that. I asked the owner of a battery shop about them, and they told me that AGM batteries have a circuit that communicates with the car, and it needs to be "introduced" to the car in order to work as designed.

Sounds like something that could explain what's happening though I spoke with a dealer service tech and he basically said that since everything is working and there are no warning lights on that everything should be ok.

I mean hopefully I'm just over thinking this...

 

[FavaBean]

My understanding is that there is no requirement for the battery to be registered when it is replaced.

 

[danzig997]

My understanding is that there is no requirement for the battery to be registered when it is replaced.

Correct, I replaced the OEM GM battery with a new one from Costco. The old weak battery disabled Stop/Start Technology. When the new battery was installed Stop/Start system worked again. No need for battery adaptation aka calibration.

 

[Displayhawk]

Not sure how many miles you have on it, but you might check the Serpentine Belt, Idler Pulley and Belt Tensioner. If the belt is slipping slightly because the belt tensioner isn't applying enough pressure, it (alternator) would still charge the battery, but not as well. Idler Pulley going out usually squeals, but not all the time. It can limit how fast the belt is turning the alternator. Not saying this is the cause! ..... Just something to check.

 

[Irock1985]

Well so far everything is still working as it should though I am still sitting at 12.5v at idle and around 13.7 when driving.

So I'm hoping the system just realizes that it's a full battery and is charging at a lower rate than what I am used to.