Need some help with 911-02r external regulator for alt please help me

[Rexdale]

So I got it installed seems installed right to me ,what happens is idle voltage is low 13.0 an at idle turning the dial left or right doesn't increase or decrease voltage but when I rev my engine from idle rpm 800 to 1000 rpm voltage jumps to 15.0v an I can turn the dial to increase or decrease , I clamped the alt an it put out 170a at 2000 rpm , im using a 12v relay 5 pin , constant power wire from batt to relay , ignition wire to relay ,wire from negative batt post to relay ,then the power wire from relay to reg , reg is grounded off to firewall , an 2 wires from alt to reg ,ground an field. I really need some help with this any thoughts please

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[sexy 10+ year member]

So I got it installed seems installed right to me ,what happens is idle voltage is low 13.0 an at idle turning the dial left or right doesn't increase or decrease voltage but when I rev my engine from idle rpm 800 to 1000 rpm voltage jumps to 15.0v an I can turn the dial to increase or decrease , I clamped the alt an it put out 170a at 2000 rpm , im using a 12v relay 5 pin , constant power wire from batt to relay , ignition wire to relay ,wire from negative batt post to relay ,then the power wire from relay to reg , reg is grounded off to firewall , an 2 wires from alt to reg ,ground an field. I really need some help with this any thoughts please

Interesting toy so was your clamp test done with a cold or hot alternator? As for the voltage question what battery were you using? I have a bench for testing alternators where I can control some things but the battery I use makes a big difference most times.

 

[Rexdale]

Interesting toy so was your clamp test done with a cold or hot alternator? As for the voltage question what battery were you using? I have a bench for testing alternators where I can control some things but the battery I use makes a big difference most times.

Alt was hot I just came back from a highway drive , batts I'm using are 3 Odyssey 2150's in the trunk an a optima yellow top up front , I got a distro block up front with 2 runs from the alt in 3 runs out to the back batts an 1 run from the distro to front batt all 0 gauge

 

[sexy 10+ year member]

Over the internet it’s hard to diagnose without the person on the other end giving good info which you are. I would test with one good battery under minimal load like parking lights only. If your are still getting 13.0 at 800RPM then I would suggest changing pulley size alternator output is not linear so what you are seeing does sound pretty normal.

Now if you were to see a big difference with one battery under a light load I would check the other batteries to make sure they are in good shape.

Still I think your fine your wiring sounds right its just a common issue with high output alts that they produce less at idle and all alternators produce about 20 percent less when hot.

 

[sexy 10+ year member]

All batteries should be exactly the same for best results.

 

[Rexdale]

Over the internet it’s hard to diagnose without the person on the other end giving good info which you are. I would test with one good battery under minimal load like parking lights only. If your are still getting 13.0 at 800RPM then I would suggest changing pulley size alternator output is not linear so what you are seeing does sound pretty normal. Now if you were to see a big difference with one battery under a light load I would check the other batteries to make sure they are in good shape.

Still I think your fine your wiring sounds right its just a common issue with high output alts that they produce less at idle and all alternators produce about 20 percent less when hot.

Okay Ill test with one batt tonite , I did have a singer alt hooked up a couple days ago an I had great idle voltage 14.8 for that past months but the reason for swapping it was cause I only get 70amps max outta it an its a 250a I had lots of problems with new rectifier new regulator so I just bought a new one.i have a stock pulley on there right now so I can put on my over drive pulley an see too , but I will def try the single batt first then tomorrow ill try the smaller pulley it that doesn't help , ill let you know the results thanks for the help

 

[Rexdale]

All batteries should be exactly the same for best results.

Lol yea I know I didn't have enough money at the time to buy 4

 

[Rexdale]

Over the internet it’s hard to diagnose without the person on the other end giving good info which you are. I would test with one good battery under minimal load like parking lights only. If your are still getting 13.0 at 800RPM then I would suggest changing pulley size alternator output is not linear so what you are seeing does sound pretty normal. Now if you were to see a big difference with one battery under a light load I would check the other batteries to make sure they are in good shape.

Still I think your fine your wiring sounds right its just a common issue with high output alts that they produce less at idle and all alternators produce about 20 percent less when hot.

Oh an a weird thing too is if my car is cold say when I wake up an start it in the morning the voltage is actually steady 15v then slowly as temp rising voltage decrease's bit by bit

 

[Buck 5,000+ posts]

It sounds like the alternator isn't charging until a certain RPM (not a rare problem). I don't think that's the regulators fault, but I'm not 100% sure. You may want to investigate that. What vehicle is it on? How high do the RPM's rev? What size pulley is on it?

 

[Rexdale]

It sounds like the alternator isn't charging until a certain RPM (not a rare problem). I don't think that's the regulators fault, but I'm not 100% sure. You may want to investigate that. What vehicle is it on? How high do the RPM's rev? What size pulley is on it?

It's 2000 Vw jetta 2L, idle rpm is 800 it's takes 900 rpm or more to jump the voltage up ,rpm go's up to 7000, the pulley size not too sure but it's a stock Pulley

 

[Buck 5,000+ posts]

Ok, that may be your problem. High rev engine's like that have a different pulley turn to magnet turn ratio I believe. Because an alt can over-spin, so higher rpm cars don't have the magnet turn quite as fast for the rpms say like my V8 Explorer does (~5200 rpm vs 7000 rpm). So I think the alt may just not be turning on. But I'm here, not there.

 

[Rexdale]

So I tried the single batt 2 different ones no luck so I just about to change the pulleys hope it works or I'm screwed

 

[sexy 10+ year member]

So I tried the single batt 2 different ones no luck so I just about to change the pulleys hope it works or I'm screwed

Changing pulley size will help. Two things people need to understand is that high output alternators require a little higher RPM than a factory alt for idle voltage to be the same.

Then you mentioned that as it heats up the voltage drops and thought that was strange. It is not it is exactly the way it should be alternators output goes down as heat goes up.

The generation of heat by electric conductors carrying current. The degree of heating for a given current is proportional to the electrical resistance of the conductor. If the resistance is high, a large amount of heat is generated, and the material is used as a resistor rather than as a conductor.

 

[Rexdale]

Changing pulley size will help. Two things people need to understand is that high output alternators require a little higher RPM than a factory alt for idle voltage to be the same. Then you mentioned that as it heats up the voltage drops and thought that was strange. It is not it is exactly the way it should be alternators output goes down as heat goes up.

The generation of heat by electric conductors carrying current. The degree of heating for a given current is proportional to the electrical resistance of the conductor. If the resistance is high, a large amount of heat is generated, and the material is used as a resistor rather than as a conductor.

Smaller pulley is on , now steady voltage is 13.9 I can now turn the dial down but not up ,still when I rev it go's to 15v where I have the dial set ,when heat ,wipers ,back widow defroster is all on I drop to 13.2 so I guess i can't really do much , I don't have my amp in cause I'm in the middle of a new build so I can't really see exactly how bad of a drop I will have at idle , I hope not to bad , with my other alt on my voltage drop at the amp was 12.8 but I was steady 14.8 an i was only ever clamping 70 amps max outta it thats why i bought a new alt to try an have a less voltage drop ,so I really don't know what to do with this gotta see what happens with my amp full tilt , I don't wana kill my batts. I would be ok burping cause I could rev my engine I don't really play music parked only when testing. I'm stuck