Battery is getting overcharged! Overdrive Pulley?

[blowncopcar]

Each morning in my G10 metro when it's under 50 degrees, my Ultraguage reads that my volts are constantly over 15.1 volts at around 65+ mph, sometimes up to 15.4 volts.... at 70 mph im at about 4100 rpm i believe (5 speed, 4.29 gearing i think, whichever is stock)
The battery is 5 months old (higher-grade), everything else is fine...
I replaced the accessary belt 6 months ago along with timing belt, and the accessary belt was too big... even tho at multiple stores and on all the websites it was the right size... i had to get one about an inch shorter than stock...
Now the owner before me had a CB Radio installed.... so could he have installed a smaller alt. pulley to generate the extra power? And would installing a stock size pulley help my MPG? I know running an underdrive pulley would help, tho ive never found one... It just looks to me that generating all these extra volts seems like a waste since i barely even have a radio and dont drive at night much...
If anyone knows why Im running so many volts and also why I lose about 100% coasting mpg whenever i turn anything electrical on, fans or lights...
Thanks

[MetroMPG]

Sounds like the voltage regulator is gone inside the alternator. That's what controls output (more than RPM -- it's not a pulley issue).

You need to get it fixed (or turn on lots of accessories to bring the voltage down) or else you'll soon cook your new battery.

I had this happen to me in my old Honda Accord on a long trip to Muskegon, Michigan and back. I ended up turning on all my lights, blower, defroster, windshield wipers, powering the windows up & down, electric antenna, etc. to keep voltage reasonable until I got home to replace the alt. (OK, maybe not ALL that stuff, but you get the idea.)

[Cobb]

ROFLMFAO!!!! Thats like saying its not the fall that kills, but its the sudden stop when you land on something.

Originally Posted by yoyoyoda

So having more amps won't necessarily overcharge a battery, but those extra volts will force the battery to overcharge. So replace the regulator unless the battery will be a cooked battery soon.

[RedDevil]

It is the volts really. If they stay in bounds the amps won't be pulled, as the battery won't overcharge then. So the alternator offers less resistance and you burn less fuel.

To go with the fall analogy; you need a certain height (voltage) to reach the speed (amps) that kills you (overcharge battery) when you land.

Overcharging the battery does not sound as bad as falling to your death, especially when served with a sandwich and a large beer...

[blowncopcar]

So my best bet is just go ahead and get a new alternator?

[some_other_dave]

Most alternators have the voltage regulator built in. Unless your car has a separate regulator, yes you just replace the alternator.

-soD

[ksa8907]

Originally Posted by yoyoyoda

Bingo, If you can get a diode pack for cheap then replace the diode pack at the same time, with alternators its always in for a "penny in for a pound" and the diode pack isnt far behind a failing voltage regulator.

All the overdrive pulley does is provide more amps (to be consumed) earlier on in the speed of the engine, ie, at lower rpm's.

Its equivalent to a stock alternator being a big chubby german chick giving you one Braunschweiger sandwich (stock alternator) vs the another big chubby german chick giving you five to fifteen (overdrive alternator) Braunschweiger sandwiches AND a large mug of Helles Bier.

The important thing to remember about amps is, you don't necesserially /need/ to consume the extra amps, they are just there to be consumed incase you DO need them, ie running a CB radio, 100 watt flood lights, etc.

So having more amps won't necessarily overcharge a battery, but those extra volts will force the battery to overcharge. So replace the regulator unless the battery will be a cooked battery soon.




The last thing to go, ironically, is the stator brushes (aka commutator).

Oh and bearings too, if you can manage to get them for cheap and get them out easily.

Otherwise just get a rebuilt one with all-new parts inside.

I think he's trying to say voltage is pushed and current is pulled.

[blowncopcar]

I checked again today and even around 1500 rpm its at 14.5 or so volts, will be getting a new alt tomorrow.... Thanks guys for the help

[arcosine]

Check out rock auto for alts.

http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=2n93ur037cl6u1jul788ju7mv7

[oil pan 4]

As the voltage reg goes out one thing that they like to do is put out more and more voltage.
That is if they dont just flat out quit.