Charging System

[Chris0222]

My 2010 SS is giving me problems. With the engine off the battery reads 12.58 VDC, post to post. While running the voltage on the volt meter in the car reads almost 14 VDC. sounds good!! When the car is hot and the air temp is over 100, the voltage drops to 12.5 VDC (battery V) then the voltage will drop to 10 VDC and the car puts itself into conserve mode. Then the battery starts discharging, at this point if the car is shut down it will not start without a jump. I suspect a bad alternator. Any thoughts???

[KaBoom1701]

Here's a repost from winterboy8 in this thread:/

http://www.camaro5.com/forums/showthread.php?t=415104


Charging System Operation

The purpose of the charging system is to maintain the battery charge and vehicle loads. There are 6 modes of operation and they include:

• Battery Sulfation Mode

• Charge Mode

• Fuel Economy Mode

• Headlamp Mode

• Start Up Mode

• Voltage Reduction Mode

The engine control module (ECM) controls the generator through the generator turn ON signal circuit. The ECM monitors the generator performance though the generator field duty cycle signal circuit. The signal is a pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generator:

Commanded Duty Cycle: Generator Output Voltage:

10%........................................... 11 V

20%........................................... 11.56 V

30%........................................... 12.12 V

40%............................................ 12.68 V

50%............................................ 13.25 V

60%............................................ 13.81 V

70%............................................ 14.37 V

80%............................................ 14.94 V

90%............................................ 15.5 V

The generator provides a feedback signal of the generator voltage output through the generator field duty cycle signal circuit to the ECM. This information is sent to the body control module (BCM). The signal is PWM signal of 128 Hz with a duty cycle of 0–100 percent. Normal duty cycle is between 5–99 percent. Between 0–5 percent and 100 percent are for diagnostic purposes.

[Eric Baker]

Automatic or manual transmission? The autos have a one way clutch on the alternator pulley that could be the culprit, I've seen a few(non Chevy) go bad. I'd say it would be the alternator either way just with the info given.

[RedRaven]

I agree with the bad cell theory. In the old days alternators charged around 14.5 volts. Fully charged battery with no load held 12.5 to 13 volts. Get the battery load tested.

[GVA 45TH 2SS]

To add to Kaboom
This is the PDF for the charging system in more depth

https://drive.google.com/file/d/0Bz3...ew?usp=sharing

[Chris0222]

It's an Automatic