Battery warning or fluke?

thebull55 · September 10, 2020

I have a 2011 Sierra SL with a 4.8L. Battery age is unknown as it was there when I bought the truck. Over the weekend we were moving our kid into their dorm and I sat out front with hazards on and nothing else. When I went to leave battery didn't have enough umph to start they truck. Jumped it and started right up and was fine stopping a couple times on the way home.

I let the truck sit overnight and then checked the battery. It read 13.3V and then 15.5V after starting the truck. No problems since.

Was this a fluke or is the battery giving a warning shot before winter? I will probably just replace the battery before winter, but just wanted to know if I am missing something.

Thanks!

chem_man · September 10, 2020

I would go ahead and replace the battery. However, most any Autozone, O'Reilly's or Advance Auto Parts will test it for free.

Most use a high end conductivity tester to check the battery, and the couple of times I've had one tested while still installed, the battery testershowed that the battery in question was in the final quarter of it's life. It would have been interesting to have been able to get the battery load tested, but none of the stores I stopped by had one for in car testing.

04z71crew · September 10, 2020

Being stranded is no fun! Sounds like the battery is on its way out but maybe it will last a bit longer? I highly recommend the duracell platinum agm batteries that can be found at batteries plus bulbs, 48 month free replacement. Excellent performance in all temps. Is it reading 15.5 volts with all accessories on? did you test off the post of battery or both that and alternator? make sure you don’t have a loose ground etc. 15.5 seems high and could be bad cell/failing battery. Before you throw in a new battery make sure your alternator is functioning correctly as to not burn it up!

Edited September 10, 2020 by 04z71crew
typo

swathdiver · September 11, 2020

17 hours ago, thebull55 said:

I have a 2011 Sierra SL with a 4.8L. Battery age is unknown as it was there when I bought the truck. Over the weekend we were moving our kid into their dorm and I sat out front with hazards on and nothing else. When I went to leave battery didn't have enough umph to start they truck. Jumped it and started right up and was fine stopping a couple times on the way home.

I let the truck sit overnight and then checked the battery. It read 13.3V and then 15.5V after starting the truck. No problems since.

Was this a fluke or is the battery giving a warning shot before winter? I will probably just replace the battery before winter, but just wanted to know if I am missing something.

Thanks!

https://www.tahoeyukonforum.com/threads/extending-battery-life.117296/

thebull55 · September 11, 2020

21 hours ago, 04z71crew said:

Being stranded is no fun! Sounds like the battery is on its way out but maybe it will last a bit longer? I highly recommend the duracell platinum agm batteries that can be found at batteries plus bulbs, 48 month free replacement. Excellent performance in all temps. Is it reading 15.5 volts with all accessories on? did you test off the post of battery or both that and alternator? make sure you don’t have a loose ground etc. 15.5 seems high and could be bad cell/failing battery. Before you throw in a new battery make sure your alternator is functioning correctly as to not burn it up!

The Duracell is on my short list for sure. The 15.5 was with only the radio on. I thought that seemed a little high.

I think I will listen to chem_man and see if I can get it tested, just to make sure. Just don't want to go into winter unsure.

Thanks!

ClipperSkipper · September 15, 2020

It's a board error on the older trucks, most prevalent after a driving rain.I'm on my third battery in 20 years, an A/C Delco from Auto Zone, $89 bucks on my dealer account, they stash them behind the counter. Battery light kept coming on, performed a starting/cranking/charging test, all okay. Hey, we gotta keep 'em going.

swathdiver · September 16, 2020

On 9/11/2020 at 4:32 AM, thebull55 said:

The 15.5 was with only the radio on. I thought that seemed a little high.

Our trucks have a smart charging system, look up RVC (Regulated Voltage Control) and EPM (Electric Power Management), that's why your voltage moves around. A bi-directional scan tool can look at BCM information, like how the charging system keeps tabs on the battery, State of Charge, Start Up State of Charge, Battery Temperature, etc.

My cheap 30 month battery is now 4 years old and has been in Florida almost all of that time, very rare indeed for this climate.

thebull55 · September 16, 2020

16 minutes ago, swathdiver said:

Our trucks have a smart charging system, look up RVC (Regulated Voltage Control) and EPM (Electric Power Management), that's why your voltage moves around. A bi-directional scan tool can look at BCM information, like how the charging system keeps tabs on the battery, State of Charge, Start Up State of Charge, Battery Temperature, etc.

My cheap 30 month battery is now 4 years old and has been in Florida almost all of that time, very rare indeed for this climate.

Very interesting. I was not aware of that. The local GMC stealer is very easy to deal with. I think I’ll stop by and have them hook it up. Thanks for the info.