Battery vs Stereo

[f5fstop]

Originally Posted by kodiakz

Rocketw19, your hearests should not draw more than about 10ma when off (that would take about a month to drain the battery).

Don't forget the other parasitic drains from the BCM/PCM/Onstar and other stock modules throughout the vehicle. If Sirius is installed like XM, it is wired directly to the battery and draws all the time; but I can't believe it would draw much juice. H2s still use the older style BCMs/PCMs which draw more load when off then the newer vehicles on the market. However, the BCM and PCM should go to sleep after 20 minutes cutting their parasitic drain by at least a half.
Here is a chart GM uses for troubleshooting that might help, if we knew the entire parasitic drain load.

Based on a 690 CCA battery with a 110 minute reserve capacity (60.5 AH) starting at 80 percent state of charge will last with a constant current draw until it reaches 50 percent state of charge.
Current Drain/days to 50% capacity
25 mA/30.5
50 mA/16.5
75 mA/11
100 mA/8.25
250 mA/3.3
500 mA/1.65
750 mA/1
1A/0.8
2A/0.4

[dochummer]

Interesting info f5fstop. My problem is that my battery will randomly die on me...pretty much over night. I have a yellowtop optima, and had it tested at a tire shop. They said the battery was good, just low on charge (11.78v), and the alternator was charging at 13.38v. I've had the air suspension module fixed previously, which took care of the problem for about a year...but now I've run into the same problem again... Any idea what would be the most likely to draw on the battery too much? I could pull the fuse to onstar - seeing as how I don't use it....

[f5fstop]

Have a reliable shop do a test to see how many amps (milliamps) are being drawn when the ignition is off, and after a wait of 20 minutes. Modules go into sleep mode after approx. 20 minutes, so the parasitic drain will go down. If there is a high drain, then start pulling fuses until the drain drops. This will tell you the circuit that is at fault.
It might be the air suspension system again.

The Onstar module draws an extremely low parasitic drain.

[kodiakz]

I have always proceeded on the 25ma or less draw to be safe. Believe it or not, the newer bcms are trickier than the old ones as any micro draw can keep them awake and kill the battery fast (learned this the hard way ). In fact, the new lan systems will draw upwards of 3 amps for up to 20 minutes after the car is turned off.