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Old 08-15-2011, 07:10 PM   #1
JoshThinnes
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What voltage should battery be at resting?

Something is draining my battery. After I got it jumped, I tested the voltage and it was over 14.1 so I'm pretty sure its not the alternator.

I tested for an amperage drain and when the car was off it read 3.8 mA. Thats pretty normal phantom drain for a car with the cabin lights on and the hood open right?

That being said, something still kills this battery. My suspicions are a Final Stage Resistor, or the nav screen that doesn't really work but 5% of the time and sometimes doesn't turn off all the way when the car is off and key out of the ignition.

What is the normal voltage for the battery after the car is off? I tested mine right after I turned off the car and it was 12.4 and then 2-5 minutes later with the doors open it read 12.2 volts. Thoughts?
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Old 08-15-2011, 07:48 PM   #2
jcns
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testing the battery right after you turn off is really not a good indicator.
While running, it should read at least 14v. So your charging system seems good.
If you drained your battery once, it's quite possible it's damaged; one of the cells is probably damaged (quite normal). In this scenario, you can jump as many times as you want, plug in a charger and none of it matters. Your battery will drain for sure because it's damaged.
What caused the battery to drain the first time? Is your battery pretty old? SOMETIMES an old battery just needs to be replaced.
Age is not the only indicator to check a battery; I have seen 20-yr batteries still running. If you drive your car regularly, the battery will stay topped off/charged up.
Let the car sit overnight or all day, while at work. If at that point your voltage is close 11.5V or lower, your battery is done. Time for a new one.
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Old 08-15-2011, 07:53 PM   #3
Vinnie Vega
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I'd test your battery first, and then the alternator. If your alt. has a bad diode it will charge when the car is running, and discharge when it's off. I'd suggest getting a used lower mileage one from a wrecking yard if this is the case.
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Old 08-16-2011, 12:27 PM   #4
JoshThinnes
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It is probably NOT the battery. It is less than a year old. No one has said what voltage it should be while off...?
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Old 08-17-2011, 03:33 PM   #5
jcns
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Quote:
Originally Posted by JoshThinnes View Post
It is probably NOT the battery. It is less than a year old. No one has said what voltage it should be while off...?
about 12v after sitting for a while.
Don't measure it right after you turn it off.
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Old 08-17-2011, 04:21 PM   #6
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12.4 to 12.6 and you can consider it fully charged.
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Old 08-17-2011, 05:08 PM   #7
mkodama
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The average lead acid voltage is 12.6-12.8 when not connected to anything. Some of the more special batteries like an Odyssey I have even seen at 12.9.
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Old 09-05-2011, 06:14 AM   #8
celluloidheros
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Hi josh, you just PM'd me. I have my car totally fixed. i had a parasitic drain which i just troubleshot and repaired, I also did the FSR. I can help you with a good procedure to decide what is draining your battery. it takes 16 mins for the car to go inbto sleep mode. The FSR can def. draing your battery but there are a few tests to decide if it's the FSR, If you need to buy a cheap FSR let me know as i have an extra one that is like new. Try pulling fuse # 41 and see if it helps your issue. Also once you pull fuse 41, measure the DC voltage on both side of the fuse termninal with the fuse out and key off. I can give you a few tips on doing the FSR as it can be very easy or a PITA.

Using an inline current meter is great, make sure it can handle 10-20 amps, I used a heavy guage wire extension and aligator clips to extend the meter so I could see it at the fuse box. Charge your battery fully with a low amp charger, like 2 amps, then measure the battery voltage and write it down, take good notes. close the trunk and turn off the interior lights, If after 16 mins, you are not drawing, <40 mamps (pull the flashlight too), then start pulling fuses while watching the amp meter. , there is a little climate thermistor fan in the ac controller that runs for awhile (fuse 63) but this does go to sleep eventually. i can sell you the FSR for 30 if you want, the good thing is that i know it works fine and if it turns out to not fix the iisue then you are not out $70 for a new one.
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Last edited by celluloidheros; 02-08-2012 at 11:54 AM.
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Old 09-05-2011, 03:36 PM   #9
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I had this exact same problem and it turned out that my alternator went bad. I even had the alternator tested at Autozone and Advance Auto and they both said that the alternator was good. I then replaced the battery under warranty to rule out battery and still had a drain going on. I removed fuses 41, 43, and 67 and the drain went away, but the battery still kept dying. I then used the OBD2 voltage testor and found out that my battery voltage was terribad. So I made this video and confirmed alternator as most likely issues.



Hope that helps.
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Old 09-05-2011, 03:42 PM   #10
got_e46
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Quote:
Originally Posted by celluloidheros View Post
Hi josh, you just PM'd me. I have my car totally fixed. i had a parasitic drain which i just troubleshot and repaired, I also did the FSR. I can help you with a good procedure to decide what is draining your battery. it takes 16 mins for the car to go inbto sleep mode. The FSR can def. draing your battery but there are a few tests to decide if it's the FSR, If you need to b uy a cheap FSR let me know as i have an extra one that is like new. Try pulling fuse # 41 and see if it helps your issue. Also once you pull fuse 41, measure the DC voltage on both side of the fuse termninal with the fuse out and key off. I can give you a few tips on doing the FSR as it can be very easy or a PITA.

Using an inline current meter is great, make sure it can handle 10-20 amps, I used a heavy guage wire extension and aligator clips to extend the meter so I could see it at the fuse box. Charge your battery fully with a low amp charger, like 2 amps, then measure the battery voltage and write it down, take good notes. close the trunk and turn off the interior lights, If after 16 mins, you are not drawing, <40 mamps (pull the flashlight too), then start pulling fuses while watching the amp meter. , there is a little climate thermistor fan in the ac controller that runs for awhile (fuse 63) but this does go to sleep eventually. i can sell you the FSR for 30 if you want, the good thing is that i know it works fine and if it turns out to not fix the iisue then you are not out $70 for a new one.
celluloid, just curious, but what did your issue turn out to be? I tracked your thread while I was having issues as well and I noticed we had a couple of fuses in common which caused problems.
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Old 09-06-2011, 09:51 AM   #11
celluloidheros
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Hi gote46, it ended up being the amplifier. See the end of thebthread:

http://forum.e46fanatics.com/showthr...e=4&highlight=

Did you have a parasitic drain from the alternator, like somehow one of the hot 12 volts lines going to the alternator got corroded and was finding ground, my guess is that the alternator was just not charging the battery up enough. Did just replacing the alternator without cleaning the terminals fixed the issue ? did the idiot light come on ? The regulators are known trouble areas so In think u could replace yours and have a spare alternator.
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