Battery/alternator Issues

Godti · April 9, 2008

I have a 2004 Chev Tahoe. We have had it now for about 2.5 weeks now. I noticed on Saturday that it had a rough start, like the battery was a little low. I got a call on Monday morning from the wife saying that the Tahoe barely started. It got her to work and again started in the evening to get her home. When I started it that evening it had a really tough time, like not enough juice from the battery. I turned it off immediatly and checked the battery connections. I then went to start it up again but all it did at this point was click.

I also have a truck, so I took the battery out of the truck and swapped them. So the tahoe battery is in my truck, and the truck battery is in the tahoe. I charged the tahoe battery that night in my truck. It started no problem in the morning, and the tahoe started no problems and ran fine with the truck battery.

I was wondering if there are any test I can do and or any opinions from people on what my issue might be. I was going to start driving the truck on a regular basis and see if it starts to get a weak start, then I would assume a new battery.

Cheers

98silvz71 · April 9, 2008

Is the alternator providing enough power to the battery in the Tahoe? It might be just under 12v and causing you the problems. Thats what happened on our 96 Lumina. One day it just started to put 11.8v out and the battery slowly lost power.

Bish · April 9, 2008

If it is charging, it shouldput out 14 volts. You can check the voltmeter in the dash or put a voltmeter on the battery when it is running and see. I had several alternators fail in 205K on my 01 Tahoe. All of them had internal voltage regulator failures.

Also, make sure to check the wiring from the alternator to the battery. If the oem battery started leaking from the post like many do it will corrode the positive wire to the point that it can kill the alternator and battery. If there is ANY green on the copper wiring, replace it.

Godti · April 9, 2008

Well keeping in mind that I just got the tahoe, I never noticed this before. The battery volt gauge is jumping between 14-15 volts while running. I didnt check with a volt meter accross the battery. The battery and posts were super clean, I gave them a quick brush anyways and put some dilectic gel on them. I will check the wiring at the alternator tonight.

Bish · April 9, 2008

Well keeping in mind that I just got the tahoe, I never noticed this before. The battery volt gauge is jumping between 14-15 volts while running. I didnt check with a volt meter accross the battery. The battery and posts were super clean, I gave them a quick brush anyways and put some dilectic gel on them. I will check the wiring at the alternator tonight.

A bouncing gauge was the first sign when mine started going bad. Mine would sit at 14.5 and the needle would bounce lower for a fraction of a second. A couple months later I noticed the lights flickering when the voltmeter bounced. A month later it wasn't charging.

Good luck.

Godti · April 9, 2008

Well keeping in mind that I just got the tahoe, I never noticed this before. The battery volt gauge is jumping between 14-15 volts while running. I didnt check with a volt meter accross the battery. The battery and posts were super clean, I gave them a quick brush anyways and put some dilectic gel on them. I will check the wiring at the alternator tonight.

A bouncing gauge was the first sign when mine started going bad. Mine would sit at 14.5 and the needle would bounce lower for a fraction of a second. A couple months later I noticed the lights flickering when the voltmeter bounced. A month later it wasn't charging.

Good luck.

You mean your alternator or battery?

Bish · April 10, 2008

Well keeping in mind that I just got the tahoe, I never noticed this before. The battery volt gauge is jumping between 14-15 volts while running. I didnt check with a volt meter accross the battery. The battery and posts were super clean, I gave them a quick brush anyways and put some dilectic gel on them. I will check the wiring at the alternator tonight.

A bouncing gauge was the first sign when mine started going bad. Mine would sit at 14.5 and the needle would bounce lower for a fraction of a second. A couple months later I noticed the lights flickering when the voltmeter bounced. A month later it wasn't charging.

Good luck.

You mean your alternator or battery?

Sorry, first sign my alternator was dying.

sam5828 · April 10, 2008

a quick test to see if the alt is good fire it up and pull one of the cables off the battery. if it stays running there is a good chance it is just the battery, if it shuts off it is the alt for sure

BurbanZ71 · April 10, 2008

a quick test to see if the alt is good fire it up and pull one of the cables off the battery. if it stays running there is a good chance it is just the battery, if it shuts off it is the alt for sure

Why not just bring it down to AutoZone, Advance, Sears, etc and ask them to test the battery & charging system. They should be able to tell you how both are.

Pulling cables while running scares me. Call me a wimp if you like...

Godti · April 10, 2008

Actuallly I used to pull the wire too, but the more I read on line about testing the more I read not to do that cause it can cause a spike the charging system which ultimately can damage the alternator (if its not messed already).

As for taking it down to a shop, Im being cheap cause all the places here will charge for the tests. But I might just do it anyways. Im gonna let it sit for a few days and see what happens to my truck battery. I will also hook kup a ammeter and see if I have any parasitic drains greater than 50 milliamps.

workahalic2 · April 10, 2008

Actuallly I used to pull the wire too, but the more I read on line about testing the more I read not to do that cause it can cause a spike the charging system which ultimately can damage the alternator (if its not messed already).

As for taking it down to a shop, Im being cheap cause all the places here will charge for the tests. But I might just do it anyways. Im gonna let it sit for a few days and see what happens to my truck battery. I will also hook kup a ammeter and see if I have any parasitic drains greater than 50 milliamps.

Sounds like the alt to me auto-zone is pretty cool about it here they advertise the service as free.(may not apply 4 you though) If your gauge is jumping its either your alts going out or shorting out and shutting off your cars computer will protect its self and has control of your alts signal.Low voltage due to a drained battery will cause excessive strain on the alt and may be overheating.Lots of possibilities.

C & A s Dad · April 10, 2008

a quick test to see if the alt is good fire it up and pull one of the cables off the battery. if it stays running there is a good chance it is just the battery, if it shuts off it is the alt for sure

Please, Please do not do this. It was "sort of" acceptable back in the 70s and maybe even in the 80s but once the internal regulators came along and then the ECM units, this test procedure became very dangerous. I am in the Auto Parts industry and I cannot tell you of how many horror stories we heard in the early 90s and even still today from this being done. It can do anything from kill your alternator, regulator to completly fry the ECM. I have seen people cost themselves hundreds of dollars from doing this.

Sam, I do not mean to sound like I am disputing you, and this can be done sometimes without damage. However, the risk is far too great to even consider it in my opinion.

Godti · April 10, 2008

So I just got the call from the Wife. The truck is dead in the driveway. So the good news is, its gotta be the battery, and the bad news is, its in front of the tahoe so she is stuck.

So my next question is, can something in the vehicle fry a battery? I mean if I throw a new battery in there will the tahoe fry it if there is something else wrong??

fatdaddy · April 10, 2008

So I just got the call from the Wife. The truck is dead in the driveway. So the good news is, its gotta be the battery, and the bad news is, its in front of the tahoe so she is stuck.

So my next question is, can something in the vehicle fry a battery? I mean if I throw a new battery in there will the tahoe fry it if there is something else wrong??

I think the OEM batteries start to go around the 36,000 to 40,000 mile window. They can be nursed for longer but it depends on how hard you use it. Locations with extreme weather, hot or cold, are hard on batteries. Since you don't know the early history, I would just replace it. The voltage irregularity you observed can be caused by a battery that is failing.

C & A s Dad · April 10, 2008

Andrew, that is good news. If you get 4 years on any battery that is pretty good and about average. Be sure you get a good battery and be careful to not overtighten the side terminals. Remember, a good CCA rating is necessary but you do not need to go above the OE recommendations unless you live in an extremely cold climate or are running a bunch of aftermarket accessories. As a rule of thumb, the higher the CCA rating, the shorter the life of the battery. This is a little oversimplified but is overall an accurate statement.

Many of the warranty issues with side terminal batteries are related to someone overtightening the bolt and breaking or loosening the post causing leaks to start.