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Battery draining / Alternator or ??? Please help

B

BlueZRX1200R

New member
I just purchased an 08 GXP. Was good to me for about one month. One day I went to start it and it flipped out! The lights blinked, dash flashed, horn blew, and the trunk popped open. Had it jump started and drove it home. The next day, tried to start it and it was completely dead.
  • I removed the battery (one year old), it fully charged and load tested fine.
  • Reinstalled battery and checked the alternator with a meter and it was reading 14.40 volts which I believe is right.
  • I did not drive it all week to see if something was draining it and it started just fine. I drove it around town for the night watching the voltage gage on the display and it stayed at 14.40 the whole time.
  • The next day it did it again and will not start????
 


When it does the "flipping out" did you measure the voltage of the battery? Specifically while cranking? Or before cranking.

If it was me I would check the battery voltage every morning before cranking. If it is low then start troubleshooting parasitic drain or insufficient charging. If voltage is 12.6v (fully charged battery) and you have trouble starting then troubleshoot bad or borderline bad battery. Measure voltage while cranking. If below 9.6v replace battery.

Parasitic drain test- Disconnect the positive cable while car turned off, insert an amp meter between battery and cable, and check for draw. If draw is over 100ma then start pulling fuses to figure out which circuit.

Don't forget to clean battery terminals and grounds. Stray grounding issues and poor contacts can cause all sorts of gremlins.
 
Never checked it while cranking. Okay, I will try this. A friend at work instructed me on how to do the light test also. Right now I'm recharging the battery. I checked it two days ago and it was 4.43 and just today it was 3.36. something is pulling a charge would you say?
 
Yeah something is killing the battery for sure. The thing that gets me is that it is something that is not controlled by the system or it would go into battery saver mode. A test light isn't really going to help as it will always light up since the system draws a few hundred milliamps. You should use a meter and actually measure amps. One with a 10 amp capacity would work. Basically the same test except you'll be able to see how many amps whatever device it is.

Jeff
 


Ok, noticed a few threads that mentioned having issues where their batteries were dying overnight caused by a bad interface module for aftermarket radios.
 
Here is a parasitic drain test. Connect an amp meter between the positive battery post and the positive cable. Measure the miliamps. If it is excessive start pulling fuses to determine where the drain is coming from. On my 04 GT, aftermarket radio, I have a 16.2 mA drain. Normal...


IMAG0514.jpg
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brettstoner said:
Here is a parasitic drain test. Connect an amp meter between the positive battery post and the positive cable. Measure the miliamps. If it is excessive start pulling fuses to determine where the drain is coming from. On my 04 GT, aftermarket radio, I have a 16.2 mA drain. Normal...


IMAG0514.jpg
[/URL]
Click to expand...


Okay, I,ll give it try. Turbocharged400sbc suggested that the care has an alarm and it could be disabling the starter? I'm thinking he might be right?
 
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