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Setting voltage on internally regulated HO alt


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I'm trying to find out how I can create a set charging point for my internally regulated HO alternator. My car will fluctuate between 15.2v on start, drop down to 13.8v then back up to 14.6v when im playing loud music. I want to switch over to a bank of lithium cells so I'd prefer to have a steady 15.2v. I talked to my alternator manufacturer who can make a voltage boost module but it costs more than the alt. 

Car is a 2009 chevy trailblazer with the 2-pin plug, with that sense wire unplugged the alt charges at a constant 14.0v.

Can I add an external regulator (transpo) with the internal regulator left untouched?

Any ideas are appreciated thanks

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I just went through this with my 05 silverado. The RVC system is crap and its probably what is causing your issue. I have a 250a 6 phase alt and I still had issues with voltage dropping off after startup. Contacted JS alternators about the issue and I was advised if I wanted to do an external reg it would have to be sent back in to be modified to run an external regulator. I was also given the option to modify the alternator to  self exciting and he would put in an internal regulator that charges to 14.8 always. I chose the second option and it fixed my issue. I also wanted to add I only had to pay 40 bucks and shipping to the shop for this fix.

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On 5/7/2019 at 11:33 AM, Kyle13130 said:

I'm trying to find out how I can create a set charging point for my internally regulated HO alternator. My car will fluctuate between 15.2v on start, drop down to 13.8v then back up to 14.6v when im playing loud music. I want to switch over to a bank of lithium cells so I'd prefer to have a steady 15.2v. I talked to my alternator manufacturer who can make a voltage boost module but it costs more than the alt. 

Car is a 2009 chevy trailblazer with the 2-pin plug, with that sense wire unplugged the alt charges at a constant 14.0v.

Can I add an external regulator (transpo) with the internal regulator left untouched?

Any ideas are appreciated thanks

Switching to external regulation is pretty easy. I did it on mine when a paperwork mixup ended with it being sent back to me internally regulated.

It basically involves removing the plastic rectifier cover on the back of the alt, then unbolting the regulator, and attaching a brush pack/plug designed for external regulation. May or may not need to solder. Contact your alt manufacturer for the plug.

 

For regulators, you're on the right track with transpo. They have 2 units; one for use up to 16v, one for use up to 20v. Both can be dialed down to the 12-13v range. No real advantage of one or the other, it's just good info to have.

I would also take the included wiring kit and toss it in the garbage. Same goes for the rest of the opinion on the internet. Power and ground for the regulator should be 8 gauge OFC. It's not necessarily for current carrying capacity as much as it is for voltage drop in the system. What I've found is this: When you have a very low resistance charging system, the resistance in the stock wiring kit can cause the alternator to pulse. What I mean, is the power for the regulator is also the sense wire. When it applies power to the field, it induces some voltage drop on power/sense, causing it to think your voltage is too low, applying more power to field, rinse and repeat until it goes full output for a second. Then when it catches up and backs off, vdrop returns to ~0, and the alt turns off. Happens again when it turns on. I've noticed it happens more at low load / low RPM operation. Ever hear of those folks on 18v blowing their amps idling in the lanes because there was a random voltage spike? Yeah that's the reason. Use 8 gauge OFC ;)

Also: It might be worth your time to replace the included potentiometer with a multi turn unit. The included pot is rather touchy and I've had difficulty setting voltage on it to exactly where I want

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4 hours ago, Picklenation said:

I just went through this with my 05 silverado. The RVC system is crap and its probably what is causing your issue. I have a 250a 6 phase alt and I still had issues with voltage dropping off after startup. Contacted JS alternators about the issue and I was advised if I wanted to do an external reg it would have to be sent back in to be modified to run an external regulator. I was also given the option to modify the alternator to  self exciting and he would put in an internal regulator that charges to 14.8 always. I chose the second option and it fixed my issue. I also wanted to add I only had to pay 40 bucks and shipping to the shop for this fix.

Be like me add a rectifier diode to the sense wire right before the alt. Can add 1 or 2 . Mine charges at a 14.8-14.9 all the time. What does it charge now?

Shakin not Stirred....my buildhttp://www.stevemead...ngle-cab-build/412 CVX

And put a sealed enclosure in your trunk cut a hole in your deck and call it ported :lol2:

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45 minutes ago, SnowDrifter said:

Switching to external regulation is pretty easy. I did it on mine when a paperwork mixup ended with it being sent back to me internally regulated.

It basically involves removing the plastic rectifier cover on the back of the alt, then unbolting the regulator, and attaching a brush pack/plug designed for external regulation. May or may not need to solder. Contact your alt manufacturer for the plug.

 

For regulators, you're on the right track with transpo. They have 2 units; one for use up to 16v, one for use up to 20v. Both can be dialed down to the 12-13v range. No real advantage of one or the other, it's just good info to have.

I would also take the included wiring kit and toss it in the garbage. Same goes for the rest of the opinion on the internet. Power and ground for the regulator should be 8 gauge OFC. It's not necessarily for current carrying capacity as much as it is for voltage drop in the system. What I've found is this: When you have a very low resistance charging system, the resistance in the stock wiring kit can cause the alternator to pulse. What I mean, is the power for the regulator is also the sense wire. When it applies power to the field, it induces some voltage drop on power/sense, causing it to think your voltage is too low, applying more power to field, rinse and repeat until it goes full output for a second. Then when it catches up and backs off, vdrop returns to ~0, and the alt turns off. Happens again when it turns on. I've noticed it happens more at low load / low RPM operation. Ever hear of those folks on 18v blowing their amps idling in the lanes because there was a random voltage spike? Yeah that's the reason. Use 8 gauge OFC ;)

Also: It might be worth your time to replace the included potentiometer with a multi turn unit. The included pot is rather touchy and I've had difficulty setting voltage on it to exactly where I want

Change the whole sense wire out to 8 gauge?

Shakin not Stirred....my buildhttp://www.stevemead...ngle-cab-build/412 CVX

And put a sealed enclosure in your trunk cut a hole in your deck and call it ported :lol2:

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26 minutes ago, BassMunky said:

Change the whole sense wire out to 8 gauge?

Correct. And the ground!

The field wire is fine as is

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