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Old 04-22-2008, 03:51 PM   #1
White 2.5rs
Scooby Guru
 
Member#: 39936
Join Date: Jul 2003
Vehicle:
99RS TWE&SCAT EJ257
Hydra+HMist+PPG+35R=DEATH

Default Please help me diagnose elecrtical problems

Problem- Had one battery die (quit holding charge after a couple months). I was also getting weird voltage changes (between 13.8 and 14.3 on my Apexi TT) and the headlights would go bright, brighter, bright, etc. I had the alternator cleaned and properly grounded, and am still getting weird voltage changes.

Heres a list of most electrical modifications while the car sat
  1. Had alternator powdercoated
  2. Had alternator disassembled, grounds cleaned, reassembled and tested "good"
  3. Relocated battery to under passenger seat
  4. Relocated engine fuse box to fender
  5. Installed custom fusebox for all gauges
  6. Installed hydramist
  7. Installed 80amp breaker in the console
  8. Used 4 ga welders wire for all major power connections
I'm still getting 13.8-14.2ish on my volt gauge. I'm thinking that is a little low.

With the ignition on, but engine off, I measured a .3v drop across the breaker. The company that sold me this told me that seems perfectly normal... it doesn't to me...

I've been told to run thicker wire, but 4ga is rated to handle 60 amps sustained.

Heres a picture
Please let me know

Alex
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Old 04-22-2008, 04:24 PM   #2
Cougar4
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Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
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I would test the alternator voltage while the engine is revving to around 2,500 RPM. Check to see if there is any AC voltage getting to the battery. You should see less than.1 volts AC. The DC voltage you stated seems about a 1/2 volt low. There may be a bad diode in the alternator.

The voltage across the breaker is ok if there was a fair amount of current running through it at the time of the test.
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Old 04-22-2008, 06:18 PM   #3
White 2.5rs
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99RS TWE&SCAT EJ257
Hydra+HMist+PPG+35R=DEATH

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Quote:
Originally Posted by Cougar4 View Post
I would test the alternator voltage while the engine is revving to around 2,500 RPM. Check to see if there is any AC voltage getting to the battery. You should see less than.1 volts AC. The DC voltage you stated seems about a 1/2 volt low. There may be a bad diode in the alternator.

Alright I will def try this tomorrow
The voltage across the breaker is ok if there was a fair amount of current running through it at the time of the test.
There was very little, it was only accessories and ecu on....
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Old 04-23-2008, 04:29 PM   #4
White 2.5rs
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Join Date: Jul 2003
Vehicle:
99RS TWE&SCAT EJ257
Hydra+HMist+PPG+35R=DEATH

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well i bought a voltmeter last night.

it measured 7mv of AC current... which is good
im now showing 14.2-14.4v at the battery post which makes me think my apexi tt is on a circuit which has voltage drop due to other loads

i guess ill see if the battery holds.
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Old 04-23-2008, 11:17 PM   #5
Cougar4
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2001 LL Bean Outback
Winestone

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Purchasing a meter is a very good investment. It will save you time and money.

The voltages you measured seem pretty good to me. Check the voltage drop across the 80 amp breaker with the engine running at around 2,500 RPM and with the headlights on, blower on high, and rear defoster on if you have that.
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