Is an alternator rebuild kit in my near future? 14.5+ V
01-12-2010, 09:56 AM
#1
Cruising
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Is an alternator rebuild kit in my near future? 14.5+ V
I have a '99 hatch 6-sp, and I don't think the wiring's been modified.
On the DIC and instrument panel, as soon as the engine's running I'm over 14 volts and it goes up to around 14.7 at cruise and just over 15 at WOT.
Since it's nominally a 12-volt electrical system, does this put me at additional risk of frying something? What would be first to go? Is there an external voltage regulator or do I have to rebuild the alternator?
On the DIC and instrument panel, as soon as the engine's running I'm over 14 volts and it goes up to around 14.7 at cruise and just over 15 at WOT.
Since it's nominally a 12-volt electrical system, does this put me at additional risk of frying something? What would be first to go? Is there an external voltage regulator or do I have to rebuild the alternator?
01-12-2010, 02:14 PM
#4
It doesn't state your location in your profile but if the car sat in a very cold climate over night, your battery will require a slightly higher voltage to charge properly. This can go as high as 15 volts. Your alternator is doing exactly what it's supposed to.
01-12-2010, 02:47 PM
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
EXACTLY! Battery state of charge, battery Temp and Battery age all determine charging voltage. 
One thing that you can do to make sure that it's just being caused by battery conditions is to make sure that the voltages on the control terminals on the connector on top of the generator are the same as battery voltage.
I have a generator schematic at home (at work now) and I will provide it to you later tonight. I will detail the pins on the connector that you need to read with a voltmeter and or check the resistance.
The 12 VDC B+ voltages that are supplied to the generator are all fused with an inline wire fuse. If that fuse or the wire is compromised, it may not allow the exact voltages that are being generated to get to the control circuit and the generator thinks it needs to increase the charging voltages to get the coorrect charging voltages. It works as a feed back system. If the feed back voltage is incorrect, or delivered to the generator incorrectly, it will cause issues like this.
One thing that you can do to make sure that it's just being caused by battery conditions is to make sure that the voltages on the control terminals on the connector on top of the generator are the same as battery voltage.
I have a generator schematic at home (at work now) and I will provide it to you later tonight. I will detail the pins on the connector that you need to read with a voltmeter and or check the resistance.
The 12 VDC B+ voltages that are supplied to the generator are all fused with an inline wire fuse. If that fuse or the wire is compromised, it may not allow the exact voltages that are being generated to get to the control circuit and the generator thinks it needs to increase the charging voltages to get the coorrect charging voltages. It works as a feed back system. If the feed back voltage is incorrect, or delivered to the generator incorrectly, it will cause issues like this.
