Ammeter vs. Voltmeter - The 1947 - Present Chevrolet & GMC Truck Message Board Network

THE "10" SILVERADO · 11-03-2010, 11:12 PM

My 77 has a voltmeter but I saw in the LMC that (I think it was) 76 and olders had an ammeter...what is the difference between them? They both show electrical charge but whats the difference and which is considered better?
Thanks

mongoose · 11-03-2010, 11:28 PM

ammeter shows how how power the truck it using/charging... and a volt will tell you how many volts you have...

use a volt meter... they are actually useful.

fixit-p · 11-03-2010, 11:31 PM

Voltmeter all the way there is a reason they don't use ammeters anymore

babyJay · 11-04-2010, 12:36 AM

ammeter=bad voltmeter=good

ammeters have the entire electrical load running "through" them, which makes for a good fire. Voltmeters are in "parallel" with the pos and neg of the system, which should be a direct reflection of the charge voltage / battery voltage due to the negative reference.

Number21 · 11-04-2010, 05:54 AM

The only problem with the ammeter is the fact that the full current has to flow through it, all the way to your dash. That's why they don't use them anymore. Besides that either one will work exactly the same, they're only going to be accurate enough to tell you if your alternator is working or it isn't. Even a voltmeter isn't accurate enough to do anymore than tell you if the alt is on or not.

My '73 has an ammeter, which is currently unhooked, probably because of the full amperage having to go through it. My '79 has the voltage gauge, but I wouldn't trust the reading on either one to tell me anything other than off or on. I'm going to keep the ammeter in the 73 just to keep it original and the voltmeter in the 79...

Jonboy · 11-04-2010, 09:21 AM

How do you unhook the ammeter, or change it to a voltmeter? I am going to put a tach cluster in my '74, and would much rather a voltage gauge. Original is kinda out the window on my truck.

**N2TRUX** · 11-04-2010, 10:44 AM

Jon- The 77+ cluster will physically fit, but need to be rewired. I would look at converting to a 78+ cluster as it has electronic oil gauge too.

For those of you that don't know, DO NOT plug a VOLT cluster to an AMP harness unless you want a smoke show.

LostMy65 · 12-27-2010, 04:16 PM

I understand extremes like the voltmeter showing 5 or 25, but mine, with engine running, is at about 14-16.
Where abouts would be a bad low or high reading?
Posted via Mobile Device

qu1cks1lver56 · 12-27-2010, 04:59 PM

anything under 12 is bad

LostMy65 · 07-02-2012, 04:38 AM

I'm currently going through my wiring in my old 65.
I think I tell in my LostMy65 thread about an electrical fire I had back in 84.
I was 19, so I wired just what was needed to get myself going.
I never got around to doing anything more before I sold it in 86/87.
Anyway...
I'm currently going through my wiring in my old 65.
I've got it all out and cleaning things up.
Looking at the wiring now, I'm pretty positive the fire was related to the Ammeter.
Most wires related to it are the ones that are totally fried.

king-918 · 07-02-2012, 10:50 AM

Think water, voltage is pressure and or potential while current is flow like (CFM) in some situations you want to know current draw but when it comes to the car starting voltage is mote important
Posted via Mobile Device

11-03-2010, 11:12 PM	#1
THE "10" SILVERADO Registered User Join Date: Sep 2010 Location: Marble Falls, TX Posts: 1,575	Ammeter vs. Voltmeter My 77 has a voltmeter but I saw in the LMC that (I think it was) 76 and olders had an ammeter...what is the difference between them? They both show electrical charge but whats the difference and which is considered better? Thanks __________________ Michael Re-starting the neglected '77...http://67-72chevytrucks.com/vboard/s...=425464&page=9

11-03-2010, 11:28 PM	#2
mongoose Registered User Join Date: Feb 2009 Location: slurrey, bc. Posts: 1,134	Re: Ammeter vs. Voltmeter ammeter shows how how power the truck it using/charging... and a volt will tell you how many volts you have... use a volt meter... they are actually useful. __________________ -'73 c/10 - Low with Go - will be complete... probably never. -'90 2wd Blazer - well... soon enough anyways. -'84 SWB - the daily gas guzzler.

11-04-2010, 12:36 AM	#4
babyJay Arrived on a Pale Horse Join Date: Mar 2007 Location: SnagTown Indiana Posts: 2,524	Re: Ammeter vs. Voltmeter ammeter=bad voltmeter=good ammeters have the entire electrical load running "through" them, which makes for a good fire. Voltmeters are in "parallel" with the pos and neg of the system, which should be a direct reflection of the charge voltage / battery voltage due to the negative reference. __________________ Jason 87 V30 350TBI/400 White w/Boss V-plow 89 R3500 CC SRW

11-04-2010, 05:54 AM	#5
Number21 Registered User Join Date: Aug 2009 Location: Oregon Posts: 611	Re: Ammeter vs. Voltmeter The only problem with the ammeter is the fact that the full current has to flow through it, all the way to your dash. That's why they don't use them anymore. Besides that either one will work exactly the same, they're only going to be accurate enough to tell you if your alternator is working or it isn't. Even a voltmeter isn't accurate enough to do anymore than tell you if the alt is on or not. My '73 has an ammeter, which is currently unhooked, probably because of the full amperage having to go through it. My '79 has the voltage gauge, but I wouldn't trust the reading on either one to tell me anything other than off or on. I'm going to keep the ammeter in the 73 just to keep it original and the voltmeter in the 79... __________________ '73 K20 Cheyenne Super Camper Special 350/TH350/NP205 sittin' on 33's. You can set my truck on fire and roll it down a hill, and I still wouldn't trade it for a Coupe de Ville.

11-04-2010, 09:21 AM	#6
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: Ammeter vs. Voltmeter How do you unhook the ammeter, or change it to a voltmeter? I am going to put a tach cluster in my '74, and would much rather a voltage gauge. Original is kinda out the window on my truck. __________________ 1974 Jimmy- 5.3/4L80e/NP241

11-04-2010, 10:44 AM	#7
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	Re: Ammeter vs. Voltmeter Jon- The 77+ cluster will physically fit, but need to be rewired. I would look at converting to a 78+ cluster as it has electronic oil gauge too. For those of you that don't know, DO NOT plug a VOLT cluster to an AMP harness unless you want a smoke show. __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"

12-27-2010, 04:16 PM	#8
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,525	Re: Ammeter vs. Voltmeter I understand extremes like the voltmeter showing 5 or 25, but mine, with engine running, is at about 14-16. Where abouts would be a bad low or high reading? Posted via Mobile Device __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

12-27-2010, 04:59 PM	#9
qu1cks1lver56 Registered User Join Date: Dec 2009 Location: Milton, FL Posts: 733	Re: Ammeter vs. Voltmeter anything under 12 is bad __________________ My 86 http://67-72chevytrucks.com/vboard/s...d.php?t=375526

07-02-2012, 04:38 AM	#10
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,525	Re: Ammeter vs. Voltmeter I'm currently going through my wiring in my old 65. I think I tell in my LostMy65 thread about an electrical fire I had back in 84. I was 19, so I wired just what was needed to get myself going. I never got around to doing anything more before I sold it in 86/87. Anyway... I'm currently going through my wiring in my old 65. I've got it all out and cleaning things up. Looking at the wiring now, I'm pretty positive the fire was related to the Ammeter. Most wires related to it are the ones that are totally fried. __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

07-02-2012, 10:50 AM	#11
king-918 Registered User Join Date: Nov 2011 Location: Oklahoma City Oklahoma Posts: 1,056	Re: Ammeter vs. Voltmeter Think water, voltage is pressure and or potential while current is flow like (CFM) in some situations you want to know current draw but when it comes to the car starting voltage is mote important Posted via Mobile Device



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