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Old 08-02-2016, 05:01 PM   #1
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Tell tale signs of bad Alternator?

Was driving up the twities today enjoying the drive when all of a sudden the Battery, ABS, and Brake lights all came on. Kinda got worried but after about 30 sec all went out and car never wavered from performing well. Then about 20 min later same thing but car just died. Could not restart it. Gave all indications of bad battery. Clicking solenoid and all electronics going haywire. Windows trying to go up/down a short margins spoiler going up down. Fortunately, the tow driver had a carry bout jumper pack that started the engine and stayed running. So, is my alternator the culprit here? Soon as he unplugged the jumper it died?

I put a charger to the battery and started car. It only shows 11.8vdc. Would even a bad battery actually show 13.8vdc if the alternator were working?

Last edited by Lapister; 08-02-2016 at 08:11 PM.
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Old 08-02-2016, 09:08 PM   #2
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11.8v is pathetic after a full charge. Are you measuring at the battery posts or the connections?
Test the battery or take it to Autozone/Pep Boys to test.Dead cell?
Make sure the battery cables/connections are clean and tight.Cut back a little insulation on the cables to make sure they are not corroded.
If it is the alternator,remember you can replace just the voltage regulator on the back of the alternator if that is faulty
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Old 08-02-2016, 10:45 PM   #3
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As an addition to Gelbster's advice, try the following:

1) Disconnect the (-) negative battery cable & connect to your charger (not maintainer). Leave on charge or at least 7-8 hours.
2) Check voltage after disconnecting battery charger for +/- 15 minutes - fully charged battery should read 12.6v.
3) Reconnect battery and start car. Check voltage across terminals with engine running - should be 13.8 - 14.2v. If voltage significantly lower the alternator is suspect.
2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
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Old 08-03-2016, 06:15 AM   #4
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How old is the battery? I had a similar episode while on a west coast trip last month. Turns out the battery was around 8 years old and simply had run it's course. One day it was holding charge and the next it simply couldn't.
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Old 08-03-2016, 04:15 PM   #5
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I charged the battery several hours and noticed no bubbling action in the cells. Battery is completely dead via Hydrometer as well. Got a new battery and this one charges with a ac charger so I know it's good. With engine running no alternator charging. So I pulled the alternator, is there a way to tell bad regulator from the windings? Would even a auto parts store be able to tell one from the other? Hate to buy a whole new Alt and find that it was just the regulator. This is tha later model 02 alt.

Thanks guys, both battery and regulator turned out bad. Ordered one from Pelican, they still seem to have the better price.

Last edited by Lapister; 08-03-2016 at 07:37 PM.
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Old 08-03-2016, 08:01 PM   #6
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While you are in there.......
1. Check the idler pulley bearings -if slightly 'rough' feeling, replace the entire pulley+bearing.
2. W/p bearing for excessive play & weepage- a potential engine wrecker
3. Drive belts

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