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Old 06-12-2013, 09:44 AM   #1
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Default Good-old alternator issue

Hey all,

I recently picked up a miata as my DD and been enjoying it until recently...
Looks like the car is having an electrical issue.

The car is 1992 NA Miata

Here's run down of my current situation

Beginning

- It was a very hot day and I was on my way back home from work: I cranked up the A/C and all of the sudden A/C stopped working, gauge needles got f'ed up, radio stopped working at mid-high RPM.

- Engine would not turn over when I got home

- I saw flickering charge light on my dash so I figured the alternator was dead (The car was on its original alternator made by Mitsu) and replaced it with a reman. alternator

- Jump started the car, everything worked great, windows rolled up & down faster, lights were brighter, etc...

**** cracking down

- The day after alternator replacement, I was on my way to work and all of the sudden I hear loud noise under the hood - Belt squeal but louder than usual (I've had my share of squealing belt during my short ownership ). The noise stopped after maybe 15 seconds.-

- Following that event, **** started to happen, wiper were slow, windows rolled up & down slowly, lights were dim, etc...

- I've used multimeter to check voltage - 11.54V not running & running. So I thought 'Man this reman alternator is indeed a ******* piece of ****'.

- I wanted to pull a final test to see if it is really a piece of junk......I pulled a ghetto method on it.......... I took the positive wire off of battery while the car was running (crossed my finger in hope for no other damage) and indeed, the car did run on alternator itself

- I took my car to advanceautoparts to get the battery tested, the worker there says it is reading low voltage but it only needs a good charge.

- I've bought a trickle charger and charged the battery until the battery is fully charged

- I've checked the ground points in trunk, engine compartment and all looks well (No corrosion)

Current status

- The charged batter was holding goold 13V engine NOT running

- The charged battery showed 14V+ when the engine was running (I thought I have fixed it the problem..... WRONG)

- I was happily on my way to work and all of the sudden I started to feel the weak electrical symptoms again........... slow wiper, windows, etc... So I check the voltage once again only to see they are draining (12V when running)

So here I am.

Summary

- Alternator replaced: Everything worked great for a day
- Battery checked out to be needing charge: Charged it
- The car does run on alternator itself (Battery disconnect test)

Guess

- The belt is not properly tensioned (However, I get no squeal)
- Alternator is fucked up regardless of its ability to run on itself & showed charging battery during cold start
- Battery is fucked up?
-


Any help would be appreciated................... !!!!!!!!!!!!!!!!
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Old 06-12-2013, 09:45 AM   #2
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two thoughts: you should never run without a battery even doing that ghetto test. I can see voltages as low as 10.5v if I keep idling with a/c and headlights on on my car, runs at 13.8v without.

your solution: You need a replacement for your replacement alternator.
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Old 06-12-2013, 09:48 AM   #3
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Quote:
Originally Posted by Braineack View Post
you should never run without a battery.
Yea, it was indeed a stupid move but did confirm that the car runs on alternator (Wouldn't be doing it again )
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Old 06-12-2013, 09:49 AM   #4
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Quote:
Originally Posted by Braineack View Post
two thoughts: you should never run without a battery even doing that ghetto test. I can see voltages as low as 10.5v if I keep idling with a/c and headlights on on my car, runs at 13.8v without.

your solution: You need a replacement for your replacement alternator.
So indeed its the alternator huh? Ugh.
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Old 06-12-2013, 09:53 AM   #5
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You may have some grounding issues. Weird things happen when you have weak grounds.
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Old 06-13-2013, 03:29 PM   #6
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just to cover all bases, what kind of trickle charger did you buy? I've damaged a battery before with a cheapo trickle charger that did not say it was ok for agm/sealed batteries. learned my lesson there and got a legit one
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Old 06-15-2013, 03:08 PM   #7
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To me, it sounds possibly like a voltage regulator In the alternator going whack or loose connections between the alternator and battery.

If it were the first option, youll need a new alternator. Have you checked to see if the reman one you got has a warranty?
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