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Trailblazer SS
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Discussion Starter #1
I went to start my tbss a few days ago and the battery was dead. I swapped in my spare optima and went on with my business. I took the battery to oreillys and they said it was bad. I had them check the alternator and he said it was overcharging the battery. With the truck off, it would read 12.8v and when I started it, it went up to 15.4v. I checked for myself later that day and when I started it, 15.4 v then after about 5 min or so, it would come down to around 13-14v. I called up a local alternator/starter repair guy and he said they dont even have these alternators listed. Any definitive way to tell if it is bad? Also where would be the best place to get one if it is bad?

2007 TBSS w/55k.
 

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TrailblazerSS
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auto zone guy told me the same thing. my battery dies everything other day if I don't drive it. I don't want to buy a battery until I know if the alt is whats junk. the battery is coming up fine.
 

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06 TrailblazerSS
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15.4V sounds normal on start up just be sure that the voltage goes back down to 13-14v. Dry cell batteries dont like being charged more than 14.5v.
 

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Ok thanks. About 2 weeks ago I started getting noise in my rear passenger speaker. I read on here and did the big 3 upgrade, but it didnt help. About a week later my battery died. I unplugged the speaker since it was starting to piss me off. I just picked up a new battery from walmart (for easy exchange) so hopefully I can plug the speaker back in with no noise!
 

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I just replaced my battery last week. When I installed the new one I started paying attention to the voltmeter in the truck, and I noticed exactly what you did. On start up, above 15, then within a couple minutes it drops back to 14 on the meter which is normal. I haven't used my voltmeter, but I think what we are seeing is normal. I just noticed it cause I was paying attention to it.
 

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TrailblazerSS
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Ok thanks. About 2 weeks ago I started getting noise in my rear passenger speaker. I read on here and did the big 3 upgrade, but it didnt help. About a week later my battery died. I unplugged the speaker since it was starting to piss me off. I just picked up a new battery from walmart (for easy exchange) so hopefully I can plug the speaker back in with no noise!
Why would the battery effect your speakers?
 

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Trailblazer SS
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Discussion Starter #8
Why would the battery effect your speakers?
I read on here that if your battery is weak, your alternator has to work harder to charge it. That extra strain on the alternator causes the noise. It is a whining engine noise that gets louder and higher pitched as you speed up. I havent reconnected my speaker yet, but will today and report back.
 

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TrailblazerSS
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I read on here that if your battery is weak, your alternator has to work harder to charge it. That extra strain on the alternator causes the noise. It is a whining engine noise that gets louder and higher pitched as you speed up. I havent reconnected my speaker yet, but will today and report back.
That is a ground issue, not alternator issue. You have a ground loop, do you have an aftermarket head unit?
 

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Discussion Starter #10
Yes I have a Kenwood DNX 7120. I already did the big three so that upgraded my grounds. It just seemed kind of obvious when my speaker started making the noise then a week later my battery is completely dead.
 

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TrailblazerSS
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Yes I have a Kenwood DNX 7120. I already did the big three so that upgraded my grounds. It just seemed kind of obvious when my speaker started making the noise then a week later my battery is completely dead.
I would use a different ground other than the provided ground through the harness. Do you have bose?

Believe me, a speaker isn't going to cause your battery to die.. LOL
 

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Envoy Denali
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The power bastards HO 250 amp alternator is a decent buy.

I had a cell go bad on my stock battery from the dealer. It does happen. The replacement I chose was an optima red top.

I had the bad cell and the 250 amp compensated pretty nicely.

The charge you're seeing like others stated is normal. You'll see a little stronger with the HO one but hey if you're in need of more amps you gotta get it. These trucks come with an under powered alternator for the amount of options you can have running on the truck it can give you a lot of drain from the system where the alternator can't recharge the battery and you end up like a lot of people with 2 days no driving and the shit is dead.

Good luck.
 

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Discussion Starter #13
I would use a different ground other than the provided ground through the harness. Do you have bose?

Believe me, a speaker isn't going to cause your battery to die.. LOL
Yes I still have bose. Im not saying my speaker caused my battery to die. Here is what Im saying:

1. Battery dies/has bad cell/wont hold charge, whatever the problem is. It is a 3 year old stock battery.

2. Alternator tries to compensate for the dead battery.

3. The extra strain on the alternator causes noise to be induced into the electrical system and heard through the speaker.

4. Replace battery and alternator is no longer overloaded trying to charge the battery. No more noise from speaker.

Good to know the charging sounds normal though. I still might look into the HO alternator though since I do have a sub and amp.
 

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The power bastards HO 250 amp alternator is a decent buy.

I had a cell go bad on my stock battery from the dealer. It does happen. The replacement I chose was an optima red top.

I had the bad cell and the 250 amp compensated pretty nicely.

The charge you're seeing like others stated is normal. You'll see a little stronger with the HO one but hey if you're in need of more amps you gotta get it. These trucks come with an under powered alternator for the amount of options you can have running on the truck it can give you a lot of drain from the system where the alternator can't recharge the battery and you end up like a lot of people with 2 days no driving and the shit is dead.

Good luck.
You mean............. The charging system can't keep up when peeps put all kinds of upgraded stuff that is not OEM in their trucks.
The factory charging system works just fine as it was intended. When peeps start changing things, is when it MAY have some trouble....
 

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I havent upgraded anything other than my cai. I had this same issue. Battery had a dead cell. Upgraded to optima battery and all has been well. One thing I have noticed since I watch the volt gauge like a hawk is that it starts with 15 and then drops down. Every now and then i notice that it will drop lower than 11 volts and sit there. Still starts each time I shut it off. Makes me wonder whats going on.
 

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TrailblazerSS
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I havent upgraded anything other than my cai. I had this same issue. Battery had a dead cell. Upgraded to optima battery and all has been well. One thing I have noticed since I watch the volt gauge like a hawk is that it starts with 15 and then drops down. Every now and then i notice that it will drop lower than 11 volts and sit there. Still starts each time I shut it off. Makes me wonder whats going on.
If it goes to 11 volts then something is wrong, that's under where your batterys resting voltage should be at. Optimas are crap, I had a few and they were terrible.
 

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2007 AWD 3SS
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If it goes to 11 volts then something is wrong, that's under where your batterys resting voltage should be at. Optimas are crap, I had a few and they were terrible.
You can't go by the dash reading. That being said, active power management will decrease voltage into the high 11's in certain conditions, such as extended driving, it's really is to save the battery from overheating and is by design. The computer actually calculates the battery charge/temperature state and supplies what ever voltage will increase battery life. A weak battery will exagerate the voltage swings as well.
 
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