Funky battery voltage - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

CamaroRBT · 10-13-2012, 06:19 PM

This morning when i was on the way to work decided to check my battery voltage. When i got to it it was registering 12.5v. Now this was cruising down the highway at 70mph 1700rpm. It went back and forth from 12.5-12.6v the whole way including city driving and red lights. Now every other car ive had registered 12.1v without the engine running and 13.9-14.1v cruising. But get this, on the way home it seamed normal to me registering from 13.8-13.9.... any ideas?

fielderLS3 · 10-13-2012, 06:37 PM

It's a fuel economy thing. Today's cars are set up to only actually use the alternator when necessary. If the battery has enough of a charge, the computer will basically turn off (or at least turn down) the alternator when it is not absolutely needed to eliminate unnecessary drag on the engine, at which point, the electrical system is basically running off the battery's ~12.6 volts alone. When the electric loads are high enough, or the battery charge is low enough, then the alternator gets turned on, and the voltage is in the typical ~14 volt range.

A lot of them will do their charging by ramping up the alternator output all the way during deceleration and braking (kinda like what hybrids do, but on a much smaller scale).

CamaroRBT · 10-13-2012, 06:40 PM

Very nice. Learn something everyday. Thank you!

10-13-2012, 06:19 PM	#1
CamaroRBT Who's Laughing Now? Drives: 2011 Camaro 1SS RS LS3 Summit White Join Date: May 2011 Location: Maryland Posts: 322 View My Garage	Funky battery voltage This morning when i was on the way to work decided to check my battery voltage. When i got to it it was registering 12.5v. Now this was cruising down the highway at 70mph 1700rpm. It went back and forth from 12.5-12.6v the whole way including city driving and red lights. Now every other car ive had registered 12.1v without the engine running and 13.9-14.1v cruising. But get this, on the way home it seamed normal to me registering from 13.8-13.9.... any ideas?

10-13-2012, 06:37 PM	#2
fielderLS3 Drives: 2016 Mazda6, 2011 Mustang 5.0 Join Date: Mar 2010 Location: Portage, Wisconsin Posts: 4,049	It's a fuel economy thing. Today's cars are set up to only actually use the alternator when necessary. If the battery has enough of a charge, the computer will basically turn off (or at least turn down) the alternator when it is not absolutely needed to eliminate unnecessary drag on the engine, at which point, the electrical system is basically running off the battery's ~12.6 volts alone. When the electric loads are high enough, or the battery charge is low enough, then the alternator gets turned on, and the voltage is in the typical ~14 volt range. A lot of them will do their charging by ramping up the alternator output all the way during deceleration and braking (kinda like what hybrids do, but on a much smaller scale). __________________ 2022 1SS 1LE (Arrived 4/29/22) "The car is the closest thing we will ever create to something that is alive." . 2022 1SS 1LE (Coming Soon)

10-13-2012, 06:40 PM	#3
CamaroRBT Who's Laughing Now? Drives: 2011 Camaro 1SS RS LS3 Summit White Join Date: May 2011 Location: Maryland Posts: 322 View My Garage	Very nice. Learn something everyday. Thank you!