NEED HELP Help with battery, or alternator problem....


Well-Known Member
First off, I have a 2010 GMC Acadia SLT. Well I was driving the other day. It started up fine, and was running fine. I got about 4 miles from the house and a message comes across the dash saying service charging system. I could see the battery volts dropping down. Then it went into battery saver mode, and started shutting off the a/c fan, and radio. So I thought I better get this home. I took it home. Not knowing whether it was the battery, or alternator. So I pull up the panel in the floor, and take a voltmeter, and the battery is at 10 volts. So I get my battery charger and hook it up, and set it on trickle charge, and run the cords through the window, and use my other car to run my errands. A few hours later I come home, and it shows the battery is charged. It was showing 12.35 volts on my voltmeter. I decided to start the car and see if the alternator was charging it. I put the voltmeter on it, and it was jumping around. It would go up to 14.2, and down to 12, and just bounce around. I just took it the alternator was bad. So I shut it off, and went in, and found a alternator for good price on the internet. So I ordered it. This happened on Monday July 1st. So my alternator is suppose to be here tomorrow. So this evening I went out, and was gonna start taking the old one off. I go to get in the acadia and the doors wont unlock. I use the key, and there was no power. I put key in the ignition and muscle the wheels to the right to try to get the inner fender off with the wheel on, and the key wont come out now. I turned wheels back every which way, and the key is stuck in there. I go check the voltage on the battery and it is 2 volts. Nothing was left on in the car. So I put the battery charger back on it, and it has been charging for 5-6 hours on the fast 10 amp charge and it went up to 6 volts in about an hour and has stayed right at 6 volts since, and isnt changing.....What could have cause the battery to go dead in 6 days with no driving it, and nothing on. Could the problem have possibly been the battery all along and not the alternator? I flipped the charger to trickle charge, and I am going to let it go all night and see if it happens to charge up. If anyone has any ideas what I should do let me know. Thanks for any help.


Lifetime VIP Supporter
If possible... Pull the Battery and take it to Autozone and request that they perform a "Load Test" (Stress Test) on it. Whenever a Lead-Acid Battery approaches the end of its life, trying to "Quick Charge" it by attempting to Drive 10 AMPS into what may be a Battery with Dead Cells... can often do more harm than good when trying to resurrect it. The Battery COULD have been the Culprit all along, but you won't know until after an Autozone Counter-Person can examine it for you.

It may seem like the Battery is NOT the Sole Bad Guy if it is Old and Worn Out and has achieved all that it can give. Or it may be that it has been receiving regular, minimal or incorrect Charging from a Bad or Improperly set up Alternator or one with a Bad rectifier. These Charging conditions can severely shorten its Life Span from an average expectancy of around (3) Years. Repeatedly Under-Charging a Battery can be as bad as allowing it to become Over-Charged.

All Batteries are manufactured of Consumable Internal Lead Casting Materials that can Die Gradually from Lead Oxidation that thins down these Internal Plates over time. Also... even the Sulfuric Acid inside of them can become contaminated...even with "Sealed Battery Casements".

The fluctuations you are seeing on the Voltmeter could mean that the Alternator Wiring Connections on the back of the Rectifier Plate may be Loose, Corroded or Broken. The Link below will provide some good Schematics that will also show where all of the Grounds are located that should be checked for looseness or corrosion and for any Broken Bonding (Ground Straps) connecting from the Engine Block over to the Lower Frame and along the upper Firewall.

The Battery Cables themselves need a close inspection for any signs of "Green" Copper Corrosion... or dissolved portions of the Cable Fasteners. These will be easier to look over if you smear a Wet Paste of Arm and Hammer Baking Soda and Water around them and look for signs of any "Bubbling" . Refrain from using this material on the Battery Negative and Positive Connections or along the top of Battery Casement.

This link leads to the "Ground" Images:

If looking these issues over does not solve the problem... come back and let us know. There are more things to consider ...but First Things First.


Well-Known Member
It is possible for a rectifier in the alternator to short out and drain the battery while not being driven.
A bad battery can also self discharge. If you can borrow a battery and see if the problem goes away that would point you in the right direction.


Well-Known Member
Well took the battery to autozone, and they said it is bad. Has bad cells in it they said. So I got a new battery. I put it on, and it tests 12.6 volts, and when the car is started it goes down to 11.8 volts and stays there and drops 11.78-11.76-11.74 and just slowly goes down. So I am guessing the alternator is bad too. I unhooked the battery, because I didnt want it to get drained and messed up either. The aternator was suppose to be here, but now its showing tomorrow. The car was idling rough and acted like it needed an idle relearn. I suppose thats from where the battery had been dead for so long. Will it relearn the idle pretty quick on an acadia? I have had the idle mess up like that on my trailblazer, and just a little bit of driving and it corrected itself. Hoping the acadia does the same.


Well-Known Member
Well, I ended up having the car towed to a mechanic. Even with a new battery it wouldnt start and run right to move it to my garage to work on. It kept locking my key in the ignition. So upon getting to the mechanic. He tells me that is the wrong type of battery. Tells me to get the original back if I can. That it probably isnt bad. So I called the place where I got the battery and pleaded my case, and they let me come in and look through their pallets of battery cores for mine, and return the battery I bought. I found my battery, and took it to the mechanic. He told me it was vented and having a non vented battery can release fumes that arent good to breathe in. He said my original battery was a better one. He said he would put it on his charger and see if it would charge up on his. I told him autozone said it was bad. Anyways the next day he called and said battery was good. He said it charged up fine and everything shows good on his tester. So next he said all the problems I was experiencing was from the alternator. He said it was triggering a security sytsem or something. So new alternator, and original battery and its all fixed.

Online statistics

Members online
Guests online
Total visitors

Members online

Forum statistics

Unanswered questions
Answered questions
Latest member
Top Bottom