80 amp relay on 1 wire alternator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**dennislbrooks** · 12-01-2019, 08:39 PM

Has anyone used a 5 pin 80 amp relay to break the one wire alternator connection to the battery when the car ignition is Off?

I have a one wire 60 amp alternator 10si on my 59 GMC. I go 3 wire alternators now.

SunSoaked · 12-03-2019, 06:02 AM

Curious what the purpose would be?

**dennislbrooks** · 12-03-2019, 09:57 AM

to kill the 35 milliamp continuous draw when ignition off

SunSoaked · 12-03-2019, 10:08 AM

Is this a common problem to all one wire alts? So, is there a module (Exciter) inside the alt that pulls this small current? I've never heard this. I never liked the 1-wire I had cause of having to rev the engine once to excite it. I ended up tossing it in the trash. Went CS 130 and never looked back.

**dennislbrooks** · 12-03-2019, 10:24 AM

As I understand yes, one wires will pull .003 amps or less with alt hooked up, key off, measuring from battery negative to positive cable off battery. And that is for a good one.

I agree going forward I only get 12si's or better with 3 wires controlled with ignition switch.

I will try the relay and let you know just for grins.

Andy4639 · 12-03-2019, 10:37 AM

That would take a very long time to kill a good battery for normal use though. if you let it sit more than you drive it then why not just put a trickle charger on it and call it good. Better yet go back to the 3 wire setup which is better anyway.

**dennislbrooks** · 12-03-2019, 11:09 AM

I won't argue that, but I have a 1 wire that I will use until it dies.

vince1 · 12-03-2019, 12:05 PM

I would only alter the wiring with relays for more important stuff like headlights or electric fans. Why not just put it on a trickle charger if the vehicle is not being used for a while? I've got the same problem BTW with a small drain that I think is coming from the newer style radio.

**dennislbrooks** · 12-03-2019, 02:18 PM

I know that some radios have memory and will have a slight draw. Same with security type items. And I do run trickle chargers. This is the only 10si I have and because the alternator has no memory to keep voltage on, I will kill it with key off. Relays are somewhat cheap.

I thank you guys for your input.

87chevy.com · 12-10-2019, 11:23 PM

Quote:

Originally Posted by dennislbrooks

to kill the 35 milliamp continuous draw when ignition off

That is not an important draw. For BMW, which I've ben a master tech for 10 years now and the draw spec is around 40 miliamp. If you have a draw problem, it's not 35 milliamp

Bigdav160 · 12-11-2019, 12:01 PM

35 milliamps will draw down a battery to the point the vehicle won't crank in less than 4 weeks. (depending on reserve capacity rating)

But 35 milliamps isn't .003 amps. Which is it?

I have a one wire alternator on my boat. It came that way from the factory. I haven't noticed any parasitic drain so I haven't bothered to measure it.

87chevy.com · 12-11-2019, 12:08 PM

Quote:

Originally Posted by Bigdav160

35 milliamps will draw down a battery to the point the vehicle won't crank in less than 4 weeks. (depending on reserve capacity rating)

But 35 milliamps isn't .003 amps. Which is it?

I have a one wire alternator on my boat. It came that way from the factory. I haven't noticed any parasitic drain so I haven't bothered to measure it.

I would say the solution is to use trickle charger on a vehicle that sits that long instead of the relay thing.

**dennislbrooks** · 12-11-2019, 08:26 PM

.003 amps or less draw is normal on a 10si 1 wire alternator with igniton off from my research

12-01-2019, 08:39 PM	#1
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	80 amp relay on 1 wire alternator Has anyone used a 5 pin 80 amp relay to break the one wire alternator connection to the battery when the car ignition is Off? I have a one wire 60 amp alternator 10si on my 59 GMC. I go 3 wire alternators now. __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T Last edited by dennislbrooks; 12-01-2019 at 08:41 PM. Reason: words

12-03-2019, 06:02 AM	#2
SunSoaked Registered User Join Date: Dec 2011 Location: Yuma Arizona Posts: 1,525	Re: 80 amp relay on 1 wire alternator Curious what the purpose would be?

12-03-2019, 09:57 AM	#3
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	Re: 80 amp relay on 1 wire alternator to kill the 35 milliamp continuous draw when ignition off __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T Last edited by dennislbrooks; 12-03-2019 at 09:59 AM. Reason: words

12-03-2019, 10:08 AM	#4
SunSoaked Registered User Join Date: Dec 2011 Location: Yuma Arizona Posts: 1,525	Re: 80 amp relay on 1 wire alternator Is this a common problem to all one wire alts? So, is there a module (Exciter) inside the alt that pulls this small current? I've never heard this. I never liked the 1-wire I had cause of having to rev the engine once to excite it. I ended up tossing it in the trash. Went CS 130 and never looked back.

12-03-2019, 10:24 AM	#5
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	Re: 80 amp relay on 1 wire alternator As I understand yes, one wires will pull .003 amps or less with alt hooked up, key off, measuring from battery negative to positive cable off battery. And that is for a good one. I agree going forward I only get 12si's or better with 3 wires controlled with ignition switch. I will try the relay and let you know just for grins. __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T Last edited by dennislbrooks; 12-03-2019 at 10:31 AM.

12-03-2019, 10:37 AM	#6
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 80 amp relay on 1 wire alternator That would take a very long time to kill a good battery for normal use though. if you let it sit more than you drive it then why not just put a trickle charger on it and call it good. Better yet go back to the 3 wire setup which is better anyway. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

12-03-2019, 11:09 AM	#7
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	Re: 80 amp relay on 1 wire alternator I won't argue that, but I have a 1 wire that I will use until it dies. __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T Last edited by dennislbrooks; 12-03-2019 at 02:19 PM. Reason: words

12-03-2019, 12:05 PM	#8
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,170	Re: 80 amp relay on 1 wire alternator I would only alter the wiring with relays for more important stuff like headlights or electric fans. Why not just put it on a trickle charger if the vehicle is not being used for a while? I've got the same problem BTW with a small drain that I think is coming from the newer style radio.

12-03-2019, 02:18 PM	#9
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	Re: 80 amp relay on 1 wire alternator I know that some radios have memory and will have a slight draw. Same with security type items. And I do run trickle chargers. This is the only 10si I have and because the alternator has no memory to keep voltage on, I will kill it with key off. Relays are somewhat cheap. I thank you guys for your input. __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T

12-11-2019, 12:01 PM	#11
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: 80 amp relay on 1 wire alternator 35 milliamps will draw down a battery to the point the vehicle won't crank in less than 4 weeks. (depending on reserve capacity rating) But 35 milliamps isn't .003 amps. Which is it? I have a one wire alternator on my boat. It came that way from the factory. I haven't noticed any parasitic drain so I haven't bothered to measure it. __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

12-11-2019, 08:26 PM	#13
dennislbrooks Registered User Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,807	Re: 80 amp relay on 1 wire alternator .003 amps or less draw is normal on a 10si 1 wire alternator with igniton off from my research __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T



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