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Discussion Starter #1
I got a full set of UR pulleys on my '97 SE-R on 10/12/04. The very same day the car died and I got a new battery and alternator (not sure what kind of alt., but probably not anything good) and was driving again. 80 days later on 12/31/04, the same thing happened, and though the car is still dead and am not positive yet what failed, it looks like the alternator, and probably the battery as well. I run a basic cd head and 4 speakers (no bass) during all driving at high volume, and an Escort Passport radar detector most of the time. What's killing my alternators? Should I put the stock alternator pulley (and A/C) back on? I still have them and the belt, but would have to take it to the mechanic, as I'm unable to do it myself - plus I wouldn't be able to trouble shoot effectively for months. Any suggestions? Anyone else have this problem? My shop is full of Honda boys who say this has never been a problem for them. Thanks for any help.
 

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Discussion Starter #2 (Edited)
Oh, also, I got the radar detector just before the pulley install. I don't think it could be merely the detector, because it wasn't even on when the car started to die (took a few minutes to die). I put it in second and ran the car at 4k to keep it going a few blocks to a gas station. The stereo was off, too, but lights were on. Do I just need to get an OEM alternator, or better? I think the first one I killed was the original at 105k miles.

One last detail: I run my headlights full-time. Is it just the combo of lights, detector, stereo, and alt. pulley, and the alternator is just working overtime all the time until it dies?
 

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Nissan Junkie
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my brother has underdrive pulleys in his IROC-Z28 and when he first installed them he had a bad run with alts aswell I think he finally put the factory alt pulley on and just left the crank pulley underdriven and that solved the problem I think it was not running fast enough and over worked the alt
 

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Destroyer of worlds.
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bingo!

simple: if your car draws more current than the alternator can supply, the alternator dies.

complex: an alternator outputs a given wattage at a given rpm. the voltage always needs to be between 11-14V, so excess wattage is converted to current(amperage) and sent to the battery to charge it.

the alternator can only convert so much wattage into current and maintain the apropriate voltage. if the car draws off more current than the alternator converts..the alternator starts dumping wattage as heat instead of converting it. the excess heat kills the alternator.
 

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Discussion Starter #5
But then, why is it happening to me and not others who are running this alt pulley? Is it because its a non-OEM alternator (I've heard the OEMs are better), plus I run my lights all the time, plus I run a radar detector? I'm wondering if I stopped running my lights and put a better alternator in there if I'd be OK, or if I should bite the bullet and just have the OEM alt pulley put back. I'd rather not de-mod because the switch would cost me ~$100 labor. The power increase on this pulley is nominal, so I don't really care about that.

Has anyone had a similar situation? I know UR makes a seperate alt pulley for stereo junkies who run mad power-hogging sound, so I'm thininking if I stop using my lights all the time, this might be enough. Plus, I might be forced to keep revving up my engine to keep the power flowing :)
 

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Destroyer of worlds.
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generally, revving the engine has zero impact on the alternator output. yes the alternator outputs more, but the spark plugs are always fireing 6-7 times more often.

the headlights and the detector are very small drains on the electrical, nothing compared to rear defogger or the stereo.
 

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Discussion Starter #7
My mechanic attributed the problem to a hose/connector/wire (?) that had come loose, and warrantied the alternator and labor on it. He didn't seem too convinced that this was the cause, but I wasn't about to mention the alt pully. Battery was fine. Bad alternator came from BAP Imports.
 

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Destroyer of worlds.
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well i got a remanufactured unit from autozone, that would've been a better bet. OEM quality but a portion of the cost.
 

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TwiztidKidd
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Did you change your belts to adapt the new pulley or you just cranked up the older ones ?

Uhh... I want this puppy once I'm done paying off the header and intake :)
 

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Discussion Starter #10
Ya, I've been running the belt recommended by UR and the Nissan mag.

My recommendation to those thinking about pullies on the b14 SE-R: get the crank and the water pump pullies, and forget about the a/c and alternator pullies - they have very little hp gain, and aren't free, plus you could have alternator problems like I did. It's just rice. Your money is better spent elsewhere. The SE-R shows nice gains on the crank and w/p belt, but not the a/c and alt one. I only got them b/c I got the whole set really cheap as a set, but would not buy them again.
 

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TwiztidKidd
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I got a Hitachi alternator from Murray's Discount Auto.. I do have problems sometimes with the alternator...when I'm running headlights 90 W each , fog lights 100 W each, headunit + amp, heat fan blasting on level 3 and rear windshield defroster on while I sit at a stop light...the voltage drops to 10.2 V... If I sit like this for a min or two the headunit shuts off but the engine doesn't stall. I cut off the rear window defroster and fog lights and everything runs good. I get the same problem during the summer when A/C is on that draws a lot of current too.
 

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Tavel said:
bingo!

simple: if your car draws more current than the alternator can supply, the alternator dies.

complex: an alternator outputs a given wattage at a given rpm. the voltage always needs to be between 11-14V, so excess wattage is converted to current(amperage) and sent to the battery to charge it.

the alternator can only convert so much wattage into current and maintain the apropriate voltage. if the car draws off more current than the alternator converts..the alternator starts dumping wattage as heat instead of converting it. the excess heat kills the alternator.
Auch.....Alternators do not work that way.

Firs some equations:

P.....Power in Watt
I.....Current in Amper
U....Voltage in Volt
R....Resistance in Ohm
B....magnetic field generated by the rotor winding
v....rotor speed ( speed of the mganetic field B )
l.....lenght of the stator winding
n....number of windings
fi.... angle in between B and l

P = U * I
R= U / I

U = v*B*l* sin(fi) (this gives voltage given by one phase. An alternataor has 3 pahses. But thats not important for understanding)

Now the alternator has a buld in regulator to adjust the current flowing into the rotor winding. This current creates the mag. field B and controlling this current controls the output voltage U. So now when v changes as you rev the engine the regulator changes the rotor current to keep the output voltage at the same level( the needed level). The current flowing out of the alternator (stator current) is calculated these way:

I = (Ug - Uc) / R Ug...generated voltage, Uc...Battery voltage

But that is not imporatnt for us.

Now why can an alternator burn when underdriving it.

Lets go back to: U = v*B*l* sin(fi) and make this one litle bit more easy

fi = 90° --> sin(fi) = 1 (construction dependent); l is a constant(this means it will not change)

U = v*B*l

Now lets say we will generate U = 14V at 3000rpm (engine)

14 = v*B*l

When the alternator is not underdriven it will run at 9000rpm (just a number)

v = 9000/60*2*pi = 9000*x --> x = (2pi/60) constant!

14 = 9000*B*l*x

lets underdrive the alt by 20% --> alternator speed is now 7200rpm at 3000rpm engine

14 = 7200*B*l*x

And here is the solution why it could burn: Now the magnetic field B has to be 20% higer to achieve the same voltage. So the rotor current has to be 20% higher too and that can burn your alternator. But if it's well designet it should not.

I am building my own pulleys and the altrenator is going to by 10% underdriven. So it was on my GA16 and no problems at all.....


Sorry I was so long and sorry for the equation's but they say more then 1000 words :)
 
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