i am installing an ampmeter in my Corsa. ( I prefer them over a volt meter) I could use some info as to where to cut in to the main harness. Does any one have a wiring diagram for this job ?

Doug Ward
Orange, Calif.
65 Corsa 180, 64 Monza convertible, 61 Lakewood, 61 Monza

A volt meter is much better and easier to install. With an amp meter when everything is working right it reads zero even if the voltage changed a little bit. The common amp meters you have to run the full alternator output to the gauge and then back to the battery. That is alot of big wire in a Corvair. With a volt meter just hook it up to the ignition and then ground the other side.

RJ tools
Salem,Oregon

For myself, I agree the ammeter is more useful.
It is also true that if you use a standard automotive ammeter you have to run long lengths of large wire.
The automotive ammeter most commonly used has a internal shunt.
You should use a ammeter with an external shunt. These are most commonly sold for Marine application. You use a external shunt mounted near the battery with two small wires carrying very little current, connecting to the ammeter itself.

Stewart warner used to have a separate meter selection for marine use, but their current web page makes no sense to me.
Summit Racing sells an assortment of shunts, but I can't find the matching meters on their web site. gggg

67-72 Chevy trucks used a external shunt type ammeter and a very ingenious shunt, but I'm not going to go into that here.

An ammeter, in an alternator-equipped vehicle, is installed in the battery pigtail so it can tell you if the battery is being charged or discharged.

To wire one, you disconnect the battery pigtail from its connection to the vehicle (this varies by EM/LM) and run a fused, 10ga wire from battery (+) to one ammeter post. Run another 10ga wire from the other ammeter post and splice into the 10ga red (black in some EMs) under the dash where it comes put of the tunnel.

All connections, splices, ammeter posts, and new 10ga wire routing must be properly done and well protected and insulated because of a high risk of short circuit and fire involved with direct-battery wiring.

Ammeters fell out of favor because a voltmeter provides more useful information and doesn't have the ammeter's safety issues.

Edit: Robert mentions a marine, shunt-type ammeter. That's not a bad option but is quite uncommon in standard, automotive aftermarket gauges. As stated, you would need to get that type from a marine catalog.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts




Edited 1 time(s). Last edit at 03/19/2023 12:22AM by cnicol.

An "Ammeter" is usually placed in line with the Positive Lead of the Battery, where is can "see" current flowing FROM the Battery (- reading) or current flowing TO the Battery (+ reading).

This is the Battery + Lead to all the electrical loads in the car EXCEPT the Starter!

Most modern ammeters use a Shunt Resistor (most of the time called a 'shunt')! This is a low resistance device that will develop a voltage (+ or - depending on current flow). The 'ammeter' is actually a Center Zero Voltmeter, that reads this voltage and is calibrated in AMPS. NOTE: The "Ammeter" and the "Shunt" need to be purchased as a pair! Different Shunts develop different output voltages and need to be matched to the "Ammeter" to give accurate readings!

While this will show the actual current load on a car without the engine running, it will be Zero or very close to Zero 99% of the time!

A Voltmeter is a better choice in almost all applications. It is easy to install and will show the 'real' voltage at the Battery. The Voltage will show if the Battery is 'run down' by some leakage current or sitting too long. It will show if the Alternator/Generator is charging at the proper setting, and can indicate Overvoltage which can occur when the Voltage Regulator fails.

My "Custom Dash" by Dakota Digital includes a Voltmeter and I find it quite useful.

JMHO!

Dale

Dale E. Smiley CPBE
Life Member The Society of Broadcast Engineers
RETIRED Broadcast Engineer
CERTIFIED CORVAIR NUT
CORSA/Circle City Corvairs/Corvair Performance Group
Avon, Indiana
WB9SFF
1967 4-Door Monza PG!

SW Marine Gauge section on the web used to be nicely organized. This took some searching back and forth with Summit to find.
A ammeter gauge requiring a shunt should have it spelled out clearly on the initial description. Summit has it hidden at the very bottom of the specs.

If you watch a ammeter on a normal basis, it will provide more info than a voltmeter.
When you start an engine, the ammeter will show a small charge and in short order, the ammeter will return to near zero as the alternator charges the battery back to a full charge.

One day you will start the engine and the ammeter will show a slightly higher reading than normal and it will take just a little longer before the needle returns to near zero. In a couple of days, the needle will be slightly higher and take slightly longer for the needle to return to zero.

In one to three weeks you will need a new battery and no voltmeter will ever tell you that.



Edited 1 time(s). Last edit at 03/19/2023 01:18AM by Richard.

I ran an amp meter for many years with heavy wire. Like most have said, most of the time it stayed centered. Then it stopped working so I went to a voltmeter. Since the wires were already installed, I ran them in parallel with the BIG RED wire to the fuse block. Everything got brighter.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

"One day you will start the engine and the ammeter will show a slightly higher reading than normal and it will take just a little longer before the needle returns to near zero. In a couple of days, the needle will be slightly higher and take slightly longer for the needle to return to zero.

In one to three weeks you will need a new battery and no voltmeter will ever tell you that."

Actually in that same situation a voltmeter would show a lower and lower voltage when you first turn the key on before you start the car. I'm not saying an ammeter isn't useful but I do agree that it is less useful than a voltmeter.

Joel
Northlake, TX
5 Ultravans, 145 Corvairs and counting...

Thanks guys. Now I realize why my boat had a shunt. Marine stuff. OK, now the cat is out of the bag though. While I was changing my AM radio to an FM one, I had disconnected the wiring to the accessory gauges under the dash so it would be easier to access the radio. In the process of hooking up the wiring , I must have miswired the amp gauge back incorrectly. I started the engine & almost immediately, the amp gauge went to full charge & then to full discharge. Cabin filled with smoke but no fire. I shut down & disconnected the battery.
I have been in the long & expensive process of installing new harnesses for the past several weeks. It was suggested to me that I should go to a volt meter but as some of you will agree with me ( and some strongly disagree), I still want to use the amp meter. The info you have sent back to me will help me do it right this time.( I hope)
Back to work. Doug

Doug Ward
Orange, Calif.
65 Corsa 180, 64 Monza convertible, 61 Lakewood, 61 Monza

Always install the Amp gage next to the fire extinguisher. Someone told me that once


Eric P.
DeWitt, IA

isucorvair Wrote:
-------------------------------------------------------
> Always install the Amp gage next to the fire extinguisher. Someone told me that once
>
>
> Eric P.
> DeWitt, IA




Its amazing what will cause smoke in the cockpit. All I did was add tow dolly with fender lights and a set of magnetic car tows lights to our first motor home. Pulling a long hill out west with the flashers on and smoke started to come out of the steering column. Holy s**t. Found out they make powered trailer harnesses after the fact, for just such a thing.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

I would put the fire extinguisher away from the amp meter, so that you don't get burnt trying to get to it.

RJ tools
Salem,Oregon