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Old 05-28-2011, 09:56 AM   #1
alpine86
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Battery issue and voltage fluctuation

Today I had a battery drain issue again.

It heppens once in every month.

Yes I drove more than an hour before this drain.

I did the leakage test and the voltimeter shows 30mA/h which is perfectly normal.

I did the full load test. I started the engine and turned on every possible electronic related. HID, fogs, full A/C, both driver and passenger heated seat, rear window heated, Audio on with full bass, DICE was connected and charging my iphone.

Now it shows 11-12V with engine on. Meaning that my battery won't get charged when I am driving if I were to use all those accessaries. Shouldn't it have to show around 14v even with full accessaries on??

This is the only possible explanation why my battery gets drained every month.

When nothing was on then my battery shows 14V.

What could be the trouble? Alternator? or Voltage regulator?

I replaced my battery 3 months ago and it worked pretty good so I don't think my battery is the problem.

Thanks for your time guys.

here is the youtube video


Last edited by alpine86; 05-28-2011 at 09:58 AM.
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Old 05-28-2011, 10:07 PM   #2
steve.325i
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Wow, yes your volatge is too low. When you car is running you should see 14v0-14v5 at the battery.

I just checked the Bentley book (p.121-9) and it states:
Engine at rest, battery fully charged : 12v6
Engine running, regulated voltage : 13v2 - 14v5
Faulty regulator of MFR : > 14v8

But then on the next page is says ...

Test alternator output using a load tester.

If a load tester is not available, a quick output test can be done by running the engine at about 2000 rpm and turning on electrical loads (fans, lights and rear windoe defroster, wipers). With all accessories on, battery voltage should be above 12v6.

I really don't know if you are going to be able to diagnose if it's the alternator or the regulator and I don't know if it matters. When you purchase a new alternator, I believe the regulator comes with it.

Comments anyone?
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Old 05-28-2011, 11:45 PM   #3
ac_2007
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Most likely a failing alternator. Operating voltage should be in the 14s or high 13s depending on how loud that dubstep is pounding the 10,000w subs.
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Old 05-29-2011, 09:10 AM   #4
alpine86
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Quote:
Originally Posted by steve.325i View Post
Wow, yes your volatge is too low. When you car is running you should see 14v0-14v5 at the battery.

I just checked the Bentley book (p.121-9) and it states:
Engine at rest, battery fully charged : 12v6
Engine running, regulated voltage : 13v2 - 14v5
Faulty regulator of MFR : > 14v8

But then on the next page is says ...

Test alternator output using a load tester.

If a load tester is not available, a quick output test can be done by running the engine at about 2000 rpm and turning on electrical loads (fans, lights and rear windoe defroster, wipers). With all accessories on, battery voltage should be above 12v6.

I really don't know if you are going to be able to diagnose if it's the alternator or the regulator and I don't know if it matters. When you purchase a new alternator, I believe the regulator comes with it.

Comments anyone?
hey what are those numbers beside "v" ??

12v6 means 12.6V ??

I will do the quick load test since my reading was done only with the engine was on.

I am sure when I accelerate my voltage might drop more. I might have to install voltage meter in cabin so I can read my Voltage while I drive.

Last edited by alpine86; 05-29-2011 at 09:11 AM.
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Old 05-29-2011, 11:29 AM   #5
kgbmw02
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Look at my thread "red batt light" you'll see that the problems is the Voltage Regulator. My voltage was low at full load, but not as low as yours.
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Old 05-29-2011, 09:30 PM   #6
alpine86
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Quote:
Originally Posted by kgbmw02 View Post
Look at my thread "red batt light" you'll see that the problems is the Voltage Regulator. My voltage was low at full load, but not as low as yours.
oh, one more thing. I went to the dealership to get a free diagnose (yes it was a promotion event) and they said A/C belts and Alt belts are cracked.

I had no problem of running my car but that's what they told me.

Do you think those cracks would affect my low voltage?

Also someone mentioned the corrosion on + terminal under the hood.

I do see some corrosion under the hood.. Here is the photo of my + terminal.



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Old 05-30-2011, 08:50 AM   #7
kgbmw02
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Originally Posted by alpine86 View Post
oh, one more thing. I went to the dealership to get a free diagnose (yes it was a promotion event) and they said A/C belts and Alt belts are cracked.

I had no problem of running my car but that's what they told me.

Do you think those cracks would affect my low voltage?

Also someone mentioned the corrosion on + terminal under the hood.

I do see some corrosion under the hood.. Here is the photo of my + terminal.



No the crack belts would not make your voltage that low. It is definitely you alternator. I would suggest you start by replacing the VR it'll cost $40 at pelican parts. I would also throw in some new belts and an idler pulley since you have to remove it to get to the Alt.
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Old 05-30-2011, 03:56 PM   #8
steve.325i
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sorry sorry sorry ... Yes, 12v6 means 12.6V

If your belts are really bad, you may get 'some' slippage, but not enough to reduce the alternator output by this much.

BUT you shoudl swap the belts out if they show cracks.
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Old 05-31-2011, 01:40 AM   #9
ac_2007
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Quote:
Originally Posted by steve.325i View Post
sorry sorry sorry ... Yes, 12v6 means 12.6V

If your belts are really bad, you may get 'some' slippage, but not enough to reduce the alternator output by this much.

BUT you shoudl swap the belts out if they show cracks.
You're the first person I've seen from Brampton! Maybe now I will finally run into another member.

Also OP I'm pretty sure "weakened" belts tend to just give out and snap or fall off the pulleys. This is assuming they would be tensioned properly in the first place.
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