2021 5.3L Tahoe Alternator voltage?

West1 · Jun 27, 2024

Those with a 2021 or newer, what’s your Alternator voltage w/engine on? From what I read, all the recent models share the same DC Delco brand, along with the AGM battery.

I’m at 13.6 and want to see if others have a similar number.

I’m starting to have electrical issues due to stock alt/battery and an added sub.

I’ve called the dealer and a few other mechanic shops to try and figure out if it’s my Alt or Battery going bad.

I purchased a ctek 7002 trickle charger and have been charging the battery on Snowflake mode. So far, my electrical seems normal since charging.

Ideally I would like to add a ** Alt but reading on the sensitivity of these new rigs makes me question my life’s choices Lol.

For that reason, Illl likely downgrade amp and replace the failing OEM part.

Antonm · Jun 28, 2024

Unfortunately it’s not as simple as what’s the running voltage. These newer cars have a “smart” alternator that turns itself off and on and changes its voltage depending on several factors/ sensor inputs, why does it do that,,,for fuel economy. Yeap another previously reliable system that’s been ruined in the name of CAFE.
…

noodlesandsam2 · Jun 28, 2024

CTEK is a good product. From my own experience with Delco Batteries, they are not to be trusted. not one last more than 15 months. AGM or regular wet cell from Interstate have been good to me over the last few years. I had a Wet Cell Die Hard top post in a BMW, that Died Hard at 11 months. Also kept alive by CTEK for 3 weeks before I cried uncle. Get the battery you have load tested.

jforb · Jun 28, 2024

Interesting about GM AGM batteries. I just replaced the original GM AGM battery in my FILs 2019 Regal, it lasted 5 years, like most batteries. I've had similar experience with other GM batteries. Maybe New York is harder on batteries than Arizona?

but like he said, you won't get much useful info about the condition of the battery or alternator by watching the volt meter in the dash. Good luck.

tom3 · Jun 28, 2024

On our 2019 I've been studying that voltage regulation with a digital readout meter. Initial start up I see near 15 volts for a few minutes, then sometimes stays around 14.3 volts. On the highway after a couple miles it will drop to 13.7 volts for a good while. Sometimes it will drop to 12.7 volts for hours on a trip, occasionally do that on local drives too. That drop makes me a bit nervous which is why I've been watching it. This is reported to improve gas mileage by I mpg or so and extends battery life too. All this is dependent on a strong battery seems like. But with a weak or sulfated battery you see a high voltage for extended periods, or constant. I'm on our third battery, OE and replacement Delcos, and now a Walmart Everstart that works perfect. Had good luck with those batteries. Could be any added high current draw devices could upset this system?

West1 · Jun 29, 2024

Has anyone swapped the alternator for a High Output Alt without having issues? I’d like to buy a stinger or mechman alt.

I do plan to swap my battery soon, I believe the ctek 7002 charger can be plugged in and hooked up to the battery wiring to trick the Tahoe into thinking the battery is still present… I need to read on this more as I was just scrolling through the instructions.

tom3 · Jun 29, 2024

Some of the smart chargers do need some resistance load to output any current. I'd hook up a small light bulb to the charger and see if it powers it. If so it probably will work for standby while changing the battery.

West1 · Jun 29, 2024

tom3 said:
Some of the smart chargers do need some resistance load to output any current. I'd hook up a small light bulb to the charger and see if it powers it. If so it probably will work for standby while changing the battery.

That’s a good idea!

Hollywood 2 · Jun 29, 2024

tom3 said:
On our 2019 I've been studying that voltage regulation with a digital readout meter. Initial start up I see near 15 volts for a few minutes, then sometimes stays around 14.3 volts. On the highway after a couple miles it will drop to 13.7 volts for a good while. Sometimes it will drop to 12.7 volts for hours on a trip, occasionally do that on local drives too. That drop makes me a bit nervous which is why I've been watching it. This is reported to improve gas mileage by I mpg or so and extends battery life too. All this is dependent on a strong battery seems like. But with a weak or sulfated battery you see a high voltage for extended periods, or constant. I'm on our third battery, OE and replacement Delcos, and now a Walmart Everstart that works perfect. Had good luck with those batteries. Could be any added high current draw devices could upset this system?

Just replaced the alternator for my 2007 Avalanche thinking the same as you. I finally bit the bullet and took it to a good mechanic and it's normal for the voltage to fluctuate. The ecm looks/ builds a history with the battery life to supposedly keep it lasting longer from not charginging it as agressively as the previous year.

Kpwweb · Oct 7, 2024

Its my experience with these trucks that the battery is a huge part of the electrical system. GM seems to have the worst agm batteries (or they sit in factory and dealer’s lots and get run down). Anytime I start to experience weird electrical issues, I put in a good Odyssey (or other good agm). Did that at year one with my 2021 (when experience a few strange electrical things), and haven’t experienced any problems or issues since.

2021 5.3L Tahoe Alternator voltage?

West1

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Antonm

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West1

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