Voltage Regulator Troubleshoot

Thanks, Fred.

Son of Norway wrote:
Did you just have the Lestek rebuilt or did you get a new alternator? As for testing, I usually just put the red test lead of my meter to the output connection on the alternator and the black one to some convenient place on the engine. But there is more to it. On Monday, contact customer support at PennTex Industries, 1-877-590-7366 (in Fort Worth TX) I have heard that they can help us poor lost souls with Lestek alternators and voltage regulators. Hopefully you can talk to an old-timer who can walk you through it. If they send you some .pdf's could you send me copies? Let us know how things go.

Miles

On Edit: I found it on another forum. Search on:

6116-9135+4-step+test+90.pdf

(Could someone help me with a clicky?)

I think this is the link you want. The link to the PDF is contained within the forum post of the link below:

pdf of alternator test

Fred

Battery is new and was fully charged. Showed 12.7v before start and 12.3volt after starting. Alternator gauge shows 10volt output. I purchased Lestek from my alternator/starter repair shop who I've used for many years. I took my old one in to rebuild which he said was $300 in parts, but he had the exact same model that some guy had as a spare who had sold his motorhome and no longer needed. The shop took it apart and checked or replaced the bearings to make sure I wouldn't have any problems. It looks new or re-built, can't imagine the shop wouldn't have tested it for output? I'll replace the voltage regulator and if still problems, I'll be taking it back to the shop. Thanks guys!

10 volts? Good way to fry a new alternator is to start it off with a poorly charged battery.

Did you just have the Lestek rebuilt or did you get a new alternator? As for testing, I usually just put the red test lead of my meter to the output connection on the alternator and the black one to some convenient place on the engine. But there is more to it. On Monday, contact customer support at PennTex Industries, 1-877-590-7366 (in Fort Worth TX) I have heard that they can help us poor lost souls with Lestek alternators and voltage regulators. Hopefully you can talk to an old-timer who can walk you through it. If they send you some .pdf's could you send me copies? Let us know how things go.

Miles

On Edit: I found it on another forum. Search on:

6116-9135+4-step+test+90.pdf

(Could someone help me with a clicky?)

Hi,

Do NOT try to start touching wires without knowing what they do, or you will be replacing your alternator again! It is not difficult to replace the voltage regulator, and that is only about $35 at the most.

Also if you run a normal alternator without the battery connected, it can go to full output and melt the diodes within the alternator. I would not be starting the engine until the regulator has been replaced.

On my Ford truck, there was a "Test" wire, and if I had connected that to the battery, it would have put 12 volts to the alternator winding, and that would have made it put out it's full rated amperage, letting me drive on when my voltage regulator failed, but I did not know that at the time. It came with the instructions for my replacement voltage regulator. . .

I ended up replacing both the alternator and voltage regulator to correct the problem. My guess is a 70 amp alternator for a Ford is a lot less than yours! I think I only paid about $35 for it.

Fred.

Thanks guys! Yes Miles, I have the Lestek, and my repairman told me to check the regulator after installation to make sure it was working properly, so he knew it wasn't built in. How do I test the voltage at alternator? I know both hot leads are to chassis & coach batteries. Do I just touch positive lead to those(one at a time), and the ground to ground(or to one of the small terminals)? At initial startup, the gauge showed 10volts, and when I turned on headlights it dropped to 8-9volts.(if that tells anybody something).

I understand the regulator you have, I have the same kind. Was it a Lestek alternator that you replaced? So the new alternator also relies on the remote regulator? I have not had any trouble with mine. With the engine running, I would check the voltage at the alternator, the chassis battery and at the house battery. I don't trust the dash gauges much. Let us know what you find. Some of the original Lestek literature is still available on the net. Find it and you should get a good idea what the output voltages should be. Good luck with your repairs.

Miles

Are you sure that it is not a battery isolator. Did you check voltage at the alternator output also. Does this item have three post on it. If so the center one is voltage from the Alternator and two outer ones are are outputs to the different batteries.


This one is for the regulator.

http://www.penntexusa.com/PX-4000-6116.pdf

And you can download also the test for the alt. at the same address.

http://www.penntexusa.com/

You may want to seek professional help with your problem. I seriously doubt that you have a firewall mounted voltage regulator for you 12 volt alternator. GM converted to internal regulators in the early 70s.
You may be looking at a diode based battery isolator?

Richard