Alternator problem
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2nd Gear
Joined: Feb 2012
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Alternator problem
Hello, I have a 1980 vette, old alternator only putting out around 5-8 volts,bought new alt. and battery, new alt is not charging battery and new alt. reading 24 volts , what could be the issue here? thanks.
Pro
Joined: Apr 2009
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Pro
Joined: Jan 2000
Posts: 569
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From: SLC, UT USA
First off, an alternator is a battery maintainer not a charger, if you have 5 to 8 volts you have a battery that needs to be charged, you have a bad battery, bad grounds, or high resistance in the positive cables. You must make sure the voltage is at 12.5 volts at the battery, the battery post in the alternator, and the starter post this should be done using different ground points to verify the grounds are good.
Excessively high voltage is a bad regulator, bad connection, bad battery, or a flying short in the rotor. If it is a cheap parts house rebuild it could be a regulator or rotor. A rotor will ohm test OK on the bench but when it is spinning at 2000 shaft RPM it can develop a short or excessive resistance which can drive the voltage up.
I bought a 200 amp unit for my 1981. Had to use a Buick alt case, was a special build. It's not listed on his web site, so you have to send him a message and ask for the details. Darren@rushps.com.
Cost was hefty, but I want something that will last forever, and 63 amps from the stock unit is a joke.
Excessively high voltage is a bad regulator, bad connection, bad battery, or a flying short in the rotor. If it is a cheap parts house rebuild it could be a regulator or rotor. A rotor will ohm test OK on the bench but when it is spinning at 2000 shaft RPM it can develop a short or excessive resistance which can drive the voltage up.
I bought a 200 amp unit for my 1981. Had to use a Buick alt case, was a special build. It's not listed on his web site, so you have to send him a message and ask for the details. Darren@rushps.com.
Cost was hefty, but I want something that will last forever, and 63 amps from the stock unit is a joke.
Last edited by dsagers; Jun 26, 2012 at 03:18 PM.
