High voltage from alternator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hevymetl · 05-11-2016, 10:25 PM

Finally got my '66 registered and on the road. It seems that it has the internally regulated alternator swap done already since there are no wires going to the old voltage regulator. I installed a new battery a couple of weeks ago since I didnt know how old the current one was. I tested the voltage at the battery and at the back of the generator. At idle I got over 15volts, and at high idle I get high 16s. At idle with lights on I get mid 13s. Im thinking this is pretty high no? What say the experts? Thanks in advance for the help.

John

Wrenchbender Ret · 05-11-2016, 10:41 PM

Way too high. You probably have a bad regulator in the alt. if it is an internal reg. If it is still the original type alt. someone may have bypassed the regulator.

hevymetl · 05-11-2016, 10:57 PM

10-4. I will have to look into wether its still the old alt or not. Thank you for the reply.

Tazimafied · 05-11-2016, 11:31 PM

Most internally regulated alternators for GM have a flat back.

The externally regulated alternator will have a "step" in the back.

There are a few different way you can go with this depending on which one you have.

hevymetl · 05-12-2016, 12:10 AM

I'll investigate and report back.

hevymetl · 05-13-2016, 03:16 PM

Just pulled the alt. Appears to be the external type. Guess I'll pick up a internal type since it seems to have had the external regulator bypassed already.

Tazimafied · 05-13-2016, 11:24 PM

If it doesn't have the bypass there are cheap kits out there to get the job done.

**Palf70Step** · 05-14-2016, 09:05 AM

You can check out my thread for the conversion (starting with #128). It also has links to others. The only thing you'll need beside the alternator is the plug for the alternator. You can undo the current wires, ditch the regulator and extra wires and have a clean setup that works great.

http://67-72chevytrucks.com/vboard/s...=627495&page=6

vince1 · 05-14-2016, 09:31 AM

The old #12 output wire if still OK I hook to terminal 2. Because of the larger capacity of the replacement I run a new #8 for the output. Brown wire for the light goes to terminal 1.

hevymetl · 05-14-2016, 02:49 PM

Thanks for the help guys. I followed one of the threads in the FAQ thread. I basically cut the regulator plug off, connected the blue and the brown together, ditched the white, then at alt I connected the blue to no.1, connected the batt wire to batt terminal along with jumper from batt terminal to no.2.
Seemed to work fine. Normal voltage (14.6ish) at all rpm ranges.

05-11-2016, 10:41 PM	#2
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: High voltage from alternator Way too high. You probably have a bad regulator in the alt. if it is an internal reg. If it is still the original type alt. someone may have bypassed the regulator.

05-11-2016, 10:57 PM	#3
hevymetl Registered User Join Date: Jan 2016 Location: westchester ny Posts: 107	Re: High voltage from alternator 10-4. I will have to look into wether its still the old alt or not. Thank you for the reply.

05-11-2016, 11:31 PM	#4
Tazimafied Registered User Join Date: Feb 2015 Location: Ridgecrest, CA Posts: 94	Re: High voltage from alternator Most internally regulated alternators for GM have a flat back. The externally regulated alternator will have a "step" in the back. There are a few different way you can go with this depending on which one you have.

05-12-2016, 12:10 AM	#5
hevymetl Registered User Join Date: Jan 2016 Location: westchester ny Posts: 107	Re: High voltage from alternator I'll investigate and report back.

05-13-2016, 03:16 PM	#6
hevymetl Registered User Join Date: Jan 2016 Location: westchester ny Posts: 107	Re: High voltage from alternator Just pulled the alt. Appears to be the external type. Guess I'll pick up a internal type since it seems to have had the external regulator bypassed already.

05-11-2016, 10:25 PM	#1
hevymetl Registered User Join Date: Jan 2016 Location: westchester ny Posts: 107	High voltage from alternator Finally got my '66 registered and on the road. It seems that it has the internally regulated alternator swap done already since there are no wires going to the old voltage regulator. I installed a new battery a couple of weeks ago since I didnt know how old the current one was. I tested the voltage at the battery and at the back of the generator. At idle I got over 15volts, and at high idle I get high 16s. At idle with lights on I get mid 13s. Im thinking this is pretty high no? What say the experts? Thanks in advance for the help. John

05-13-2016, 11:24 PM	#7
Tazimafied Registered User Join Date: Feb 2015 Location: Ridgecrest, CA Posts: 94	Re: High voltage from alternator If it doesn't have the bypass there are cheap kits out there to get the job done.

05-14-2016, 09:05 AM	#8
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,216	Re: High voltage from alternator You can check out my thread for the conversion (starting with #128). It also has links to others. The only thing you'll need beside the alternator is the plug for the alternator. You can undo the current wires, ditch the regulator and extra wires and have a clean setup that works great. http://67-72chevytrucks.com/vboard/s...=627495&page=6 __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

05-14-2016, 09:31 AM	#9
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,170	Re: High voltage from alternator The old #12 output wire if still OK I hook to terminal 2. Because of the larger capacity of the replacement I run a new #8 for the output. Brown wire for the light goes to terminal 1.

05-14-2016, 02:49 PM	#10
hevymetl Registered User Join Date: Jan 2016 Location: westchester ny Posts: 107	Re: High voltage from alternator Thanks for the help guys. I followed one of the threads in the FAQ thread. I basically cut the regulator plug off, connected the blue and the brown together, ditched the white, then at alt I connected the blue to no.1, connected the batt wire to batt terminal along with jumper from batt terminal to no.2. Seemed to work fine. Normal voltage (14.6ish) at all rpm ranges.



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