Mark567

Hey everyone!

I accidentally ran the battery in my 09 Tahoe down the other day, it’s a 6 month old AC Delco OEM battery. I gave it a jump, checked it with my scanner (Innova 3160) and it said I have a “surface charge” and to run the high beams for 5 minutes to dissipate it. Did that a couple of times actually.

I also put a charger on it because the alternator was running maxed out and couldn't make up the difference.

The standing voltage on the battery now ranges from 12.7 - 13.0 volts and the charging system is steady at 14.5 volts, but the voltage gauge is not variating like it should (and did until this happened). I took it to my local shop and the owner put his Snap On scanner on it and it’s not showing anything, all clear.

No codes, no lights and nothing on the DIC.

Will this just take a while to level out?

Is there something that needs to be reset?

Or, did I mess something up?

Any help or ideas are more than welcome! I’m scratching my head here.

Thanks,

Mark

tech2

normal fully charged battiers measure 12.6 volts or 2.1 volts per cell x 6 cells. Any readings higher that 12.6 with the engine off is a surface charge caused from charging the battery. The only time surface charge is of any imporatance is when testing the battery with a conductance tester. Since this type of tester doesn't put a load on the battery; they want you to load the battery to disipate the surface charge before running the test. turning on the headlights with the engine off creates a load to remove this surface charge.


no idea why a scan tool cares about surface charge...its made to run when the vehicle is charging the battery.

depending of the charging mode; there are 10 modes, the battery state of heath, the chargine system can vary from 12.6 to 15.5. Are you using a lead or agm battery?

have the battery load tested if you are unsure about it health. the charging system, based on the limited info provided, seems to be operating normally.

SabrToothSqrl

...Does the car start when you need it to? No lights on...?

You're fine.

Mark567

It’s fixed now.

I had the battery and everything tested and everything is working but the scanner is saying the CAT and EVA monitors haven’t run. I looked that up and found a drive cycle would resolve that. I did the cycle this morning (luckily I live on a country highway) and just as soon as I finished it the voltmeter began to drop and it now goes through the different stages of charging modes.

The monitors haven’t run yet as it can take up to 5 cycles to determine the state of the catalyst but whatever else happens during the drive cycle must also include resetting the RVC system as well.

So it’s safe to say if you change your battery and don’t maintain current on your system or you run your battery down you could cause a few different problems, or more

Mark567

Here's a link to the site where I got the drive cycle info from.

General Motors Driving Cycle

SabrToothSqrl

Good to know. I put a yellow top in my 09, back in 09, and haven't had an issue since.

The OEM battery wouldn't let me run the radio while washing the truck. In under an hour of washing/drying/cleaning, it would be DEAD.
After 3 replacements under warranty, I just got a better battery.

Yellow top now has 9 years of use, and starts the truck every time...