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Author Topic: 12V Amp Meter Dash Gauge Wiring Question  (Read 6070 times)
Dreamscape
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« on: December 17, 2006, 10:33:50 AM »

I am tring to figure out to hook up a 12v amp meter on the dash of our Eagle 01.

It is not original, my electrical schematic show only a generator light diagram. The gauge is on the dash, (came this way when I bought the coach).

I have never done this so I need your help

On the back of the gauge is two terminals.

Am I right to assume that one wire coming from the ignition switch goes to one side, the other is wired from the voltage regulator.

I seached the net and found some information regarding a shunt. What is it, do I need one?

HELP!

Paul

Dreamscape
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DrivingMissLazy
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« Reply #1 on: December 17, 2006, 10:52:59 AM »

Typically an ammeter is actually a voltmeter reading a voltage drop across a shunt. A shunt is a low restive type element that is connected in series with the output lead of the alternator.
The shunt has four leads. Two heavy leads that all the current passes thru. Two additional leads that are across only a portion of the shunt and provides a voltage in direct proportion to the current.
For example, a 100 amp rated shunt may provide an output voltage of 0 to 1 volt. This would be connected to a voltmeter with a full scale range of 0 to 1 volt. In this example then 100 amps of actual current would provide one volt and the "ammeter" would read full scale. It would be calibrated to read  from 0 to 100 amps, but is actually Reading 0 to 1 volt.
Generally you would buy an ammeter calibrated to read the amps you want and a shunt that would match the meter scale and the full real amps you want to measure.
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JackConrad
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« Reply #2 on: December 17, 2006, 01:13:44 PM »

Since the amp meter is not original, what is the max reading of the amp meter? Is it large enough for your handle to output of your alternator?  Jack
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Dreamscape
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« Reply #3 on: December 17, 2006, 01:56:06 PM »

Jack,

60 amp meter.

If the bus has the original alternator, which is 250 amp, will it work?

I do not know the output as I am trying to find some group 31 batteries. No luck on Sunday, of course.

Thanks,

Paul

Dreamscape
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DrivingMissLazy
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« Reply #4 on: December 17, 2006, 02:04:13 PM »

If the meter is scaled for 60 amps, and the alternator is 250 amps, then you have a problem. Because the meter is scaled for 60 amps, it is still probably a 50 ma or 1 amp or something like that full scale, but I do not think there is anyway to get an accurate reading of actual alternator amps. I think you will have to acquire an ammeter that is scaled for probably 0-300 amps and the appropriate shunt that goes with that rating. The ammeter never carries the full amps of the alternator. Except for maybe a Model A ford. I think that ammeter was actually a 25 amp ammeter with all the amps actually running thru the meter.
Richard

Jack,

60 amp meter.

If the bus has the original alternator, which is 250 amp, will it work?

I do not know the output as I am trying to find some group 31 batteries. No luck on Sunday, of course.

Thanks,

Paul

Dreamscape
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Dreamscape
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« Reply #5 on: December 17, 2006, 02:10:54 PM »

Thanks,

I will chuck this ideal until I get to Abilene.

Paul

Dreamscape
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Hartley
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« Reply #6 on: December 17, 2006, 02:47:55 PM »

You need a shunt type remote reading meter for you application.

The shunt would go in the line from the alternator. Or like a trimetrics works by installing in the negative line from the batteries to chassis ground. So it will read charge and disharge amps.

The meter head is a low voltage-low current meter and carries no actual current. that's all handled at the shunt...

An automotive after market meter probably will not work in your application.

One from a Heavy duty Semi truck or ambulance with the correct shunt block is more what you need.

Dave...
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Dreamscape
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« Reply #7 on: December 17, 2006, 03:27:23 PM »

Thanks,

I have always dealt with auto stuff, I forgot I must deal with the BIG BOY STUFF. Grin

I will do more research once I am settled.

All of you, Jack, Richard and Dave, Thank You so much for your valued imput.

Paul

Dreamscape
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