l5p 220 denso alternator on a lbz

chrisuns

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Sep 11, 2009
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Yeah, but I've also did the big three upgrade years ago too; I think I went with 00 or 000 for this alternator though - I had some laying around from a piece of heavy equipment.
 

DAVe3283

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I'm still running the stock fuseable link from my LB7 alternator with an aftermarket 300 amp alternator LOL One day it'll pop and I'll put some real cable on. But since the ECU controls the field to regulate voltage as measured by the ECU, any losses in the undersized cable are compensated for :spit:

I've been considering an upgraded alternator for my Suburban. Think the Desno 220 will work on a LB7? It has the stock 140 amp, but with the quadrasteer I'd feel better with a bit more power available. I don't know if the LB7 and LBZ alternators are compatible.
 

THEFERMANATOR

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I'm still running the stock fuseable link from my LB7 alternator with an aftermarket 300 amp alternator LOL One day it'll pop and I'll put some real cable on. But since the ECU controls the field to regulate voltage as measured by the ECU, any losses in the undersized cable are compensated for :spit:

I've been considering an upgraded alternator for my Suburban. Think the Desno 220 will work on a LB7? It has the stock 140 amp, but with the quadrasteer I'd feel better with a bit more power available. I don't know if the LB7 and LBZ alternators are compatible.

Pretty sure the ecm simply controls the field wire as the regulator has an internal voltage sense. The 4 wire regulators werent for the variable charging system, those were the 2 wire regulator's that used ecm/pcm voltage control.
 

DAVe3283

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Hmm, I think you're right. Thinking about it more, on cold starts, the voltage comes up to 13 right away, then jumps up to 14 once the glow plugs are off. I bet that's the voltage drop across the fuseable link I'm seeing.

Maybe I'll put a new one on sooner than later.
 

gmduramax

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Jun 12, 2008
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Hmm, I think you're right. Thinking about it more, on cold starts, the voltage comes up to 13 right away, then jumps up to 14 once the glow plugs are off. I bet that's the voltage drop across the fuseable link I'm seeing.

Maybe I'll put a new one on sooner than later.

Just pop the hood and feel how hot the cable is.
 

THEFERMANATOR

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Hmm, I think you're right. Thinking about it more, on cold starts, the voltage comes up to 13 right away, then jumps up to 14 once the glow plugs are off. I bet that's the voltage drop across the fuseable link I'm seeing.

Maybe I'll put a new one on sooner than later.

I've noticed on mine the ecm shuts the glows off early once voltage pops above 13 volts. I've only got a 130 amp ad244, but they're well documented doing well over max output at idle when cold. The ecm will shut the glow plugs off on mine in well under the 30 seconds I have them set to run if voltage touches 13.
 

chrisuns

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I wouldn't see why it wouldn't work with an LB7, I have mine wired to the brown wire on the main alternator. Fairly certain the LB7 ECM controls the alternator so it's just a matter of splicing it in.
 

THEFERMANATOR

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I wouldn't see why it wouldn't work with an LB7, I have mine wired to the brown wire on the main alternator. Fairly certain the LB7 ECM controls the alternator so it's just a matter of splicing it in.

ECM alternator control where it controlled the charging voltage didn't start on the duramax until the LMM(didn't start until 04/05 on 1500's). They kept the 4 pin plug through at least the LBZ. The ECM simply turned on a keyed on power to field it, and monitored the charge circuit. If you run a 2 wire plug alternator on a different vehicle, you only get 13.8 volts default voltage output.

I know for a fact my lb7 uses an old style alternator and is wired like factory where the ECM fields it. I know somebody else who wired in an older cs144 to his LB7 using the factory wiring to trigger it. Its easy enough to get a 200 or even 300 amp ad244 if one wants it.
 
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DAVe3283

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ECM alternator control where it controlled the charging voltage didn't start on the duramax until the LMM(didn't start until 04/05 on 1500's). They kept the 4 pin plug through at least the LBZ. The ECM simply turned on a keyed on power to field it, and monitored the charge circuit. If you run a 2 wire plug alternator on a different vehicle, you only get 13.8 volts default voltage output.

I know for a fact my lb7 uses an old style alternator and is wired like factory where the ECM fields it. I know somebody else who wired in an older cs144 to his LB7 using the factory wiring to trigger it. Its easy enough to get a 200 or even 300 amp ad244 if one wants it.

I have a 300A modded AD244 on my GMC. I was thinking the L5P alternator might be cheaper than a modded AD244, hence my interest. A high quality AD244 in the 200+ amp range is $300+, and it looks like the L5P 220 amp is $250-ish.
 

THEFERMANATOR

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I have a 300A modded AD244 on my GMC. I was thinking the L5P alternator might be cheaper than a modded AD244, hence my interest. A high quality AD244 in the 200+ amp range is $300+, and it looks like the L5P 220 amp is $250-ish.

The only problem I see is the 2 pin regulator. They're meant for ECM/PCM voltage control of the alternator. Without ECM/PCM control they're only supposed to output 13.8 volts is how I understand the 2 pin regulator. If it's a ad/dr series you can easily swap out the 2 pin regulator for a 4 pin, not sure about the alternator in the l5p though. And the ad244 at 145 amps is well documented at putting out well over its rating with many 145 amp models pushing 200 amps.