[sworn]

So I noticed my 19 SS with 580 miles on the odo cranked a bit slow this morning.

The car was purchased in Dec of 2019 and stored until March of this year. During storage I used the optional "Camaro" trickle charger. As I was cruising I noticed the volt gauge was about 12.5ish under load.

My Camaro is NOT my DD and may sit for a couple days or a week depending on my work schedule and weather.

Is the 12.5-12-8,9 reading about normal? I've heard that these batteries have a history of premature failure.

Thanks in advance!

[Baddawg53]

That volt reading is normal, it'll fluctuate up to 14 and back down as the alternator turns on and off.

[sworn]

Originally Posted by Baddawg53

That volt reading is normal, it'll fluctuate up to 14 and back down as the alternator turns on and off.

Okay, good to know. Thanks!

[Racerman27410]

if you have been keeping it on the tender then the battery is most likely fully charged and the volts wont be reading high. These are high compression engines and IMO the starter is just adequate for spinning them cold AND hot. But yeah.. slow starts are normal for this beast.

[RWT]

GM has a "Smart" charging system that uses up to 9 different modes (depending on vehicle). It uses these system modes to maintain a proper state of charge (SOC). If you are the least bit old school it's really strange.

Flooded batteries don't handle discharge (deeper cycling) well so older charging systems generally ran high a lot of the time. AGM batteries, however, are very sensitive to over-charging but handle deeper cycling better. AGM batteries also charge much faster (less internal resistance).

The smart charging system will charge high (14+) after starting (starting mode, one of the 9 modes) but it won't stay there long at all because the AGM battery charges faster and doesn't like being over-charged.

When "cruising" along the charging system will go into "economy mode" to save fuel (alternators use horsepower) and your voltage output will drop lower. There's even a mode where it doesn't charge at all. You may even see an increase in output when decelerating as the system uses the RPMs to increase your charging rate while not impacting fuel usage (kind of like regenerative braking, if you will).

So watch your readout for a high number (14+ probably) upon start but diminish relatively quickly. While cruising you likely see relatively low charging rates. The smart charging systems tries to maintain a steady "state of charge" (SOC) by reducing the time spent at high charging and discharging rates.

I am not saying your battery is not going bad because sometimes batteries just do so. However, it's likely the reading is in the 12s because your battery is fully charged at the time and the system has gone into economy mode as you cruise along.

JMHO
No expertise implied or expressed

[sworn]

Originally Posted by Racerman27410

if you have been keeping it on the tender then the battery is most likely fully charged and the volts wont be reading high. These are high compression engines and IMO the starter is just adequate for spinning them cold AND hot. But yeah.. slow starts are normal for this beast.

Good to know! Was a bit worried as the car sits for a while.

[sworn]

Originally Posted by RWT

GM has a "Smart" charging system that uses up to 9 different modes (depending on vehicle). It uses these system modes to maintain a proper state of charge (SOC). If you are the least bit old school it's really strange.

Flooded batteries don't handle discharge (deeper cycling) well so older charging systems generally ran high a lot of the time. AGM batteries, however, are very sensitive to over-charging but handle deeper cycling better. AGM batteries also charge much faster (less internal resistance).

The smart charging system will charge high (14+) after starting (starting mode, one of the 9 modes) but it won't stay there long at all because the AGM battery charges faster and doesn't like being over-charged.

When "cruising" along the charging system will go into "economy mode" to save fuel (alternators use horsepower) and your voltage output will drop lower. There's even a mode where it doesn't charge at all. You may even see an increase in output when decelerating as the system uses the RPMs to increase your charging rate while not impacting fuel usage (kind of like regenerative braking, if you will).

So watch your readout for a high number (14+ probably) upon start but diminish relatively quickly. While cruising you likely see relatively low charging rates. The smart charging systems tries to maintain a steady "state of charge" (SOC) by reducing the time spent at high charging and discharging rates.

I am not saying your battery is not going bad because sometimes batteries just do so. However, it's likely the reading is in the 12s because your battery is fully charged at the time and the system has gone into economy mode as you cruise along.

JMHO
No expertise implied or expressed

Again, great information! In regards to be a little old school, my first car was a 1976 Oldsmobile Omega!