 alternator dead ??? |
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| SirAndy |
  Jan 16 2006, 11:23 AM
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Resident German  Group: Admin Posts: 41,669 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California  |
my volt-meter dropped to ~10V while driving, dead battery i thought ...
i measured the battery with the car turned off, 12.5V on the terminals. i started the car, 11.5V on the terminals. checked at the alternator, 11.5V ... alternator dying ??? (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif) Andy |
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| dmenche914 |
Jan 16 2006, 12:40 PM
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Senior Member Group: Members Posts: 1,212 Joined: 27-February 03 From: California Member No.: 366 |
Per offical VW manual 1970-1978 for Bug Ghis, etc...
section 8, subsection 4.3: ".....In normal charging, the battery is considered fully charged when it is gassing freely and the voltage of the individual cells has risen to 2.5 to 2.7 volts each (about 15 volts for the battery). An hour or so after you have switched off the charging current, use the voltmeter /tester to determine the rest voltage of the battery. This should be 2.1 to 2.2 volts per cell, or approximately 12.5 to 13.0 volts for the battery." So 12.5 volts is on the low end for the rest voltage, and much too low for a battery that has just come off charge. note it is not totally clear to me on: "use a voltmeter tester" if the test is under load or not, the "tester" pictured in fig 4-1, captioned; using voltmeter to test total voltage of battery" shows a meter with a load attached. An extra load on the battery will drive down the voltage. Sir Andy: is the battery voltage you meaured with the battery connected, or disconnected to the car? If connected the lower reading may be ok, if there is drain on it (radio, short, alarm etc....) If disconnected, and just after you charged it, then the read is low. If still connected, and/or it has not been recently ran (ie charged) then 12.5 may be just fine. Just be sure to check all the groundstraps before chucking the alternator, bad ground straps can cause chronic under charging. good lcuk |
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Posts in this topic
SirAndy alternator dead ??? Jan 16 2006, 11:23 AM
Joe Sharp Andy: Check voltage before the regulator, should b... Jan 16 2006, 11:30 AM SLITS Es ist tot meine Furher................... Jan 16 2006, 11:31 AM dmenche914 12.5 is a bit low for a battery. I'd first tr... Jan 16 2006, 11:38 AM lapuwali I disagree. 12.5v for a battery w/o the alternato... Jan 16 2006, 11:48 AM SLITS A charged battery will see 12.5 volts...if checked... Jan 16 2006, 01:04 PM
r_towle Andy,
Go to Sears and have them put an AMP test on... Jan 16 2006, 01:13 PM |
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