Iv been looking at putting an amp meter in my 86 chevy to moniter the cummins when it gose in. I know volts and amps is kind of like torqe and horsepower ,id like it it if someone could explain more about the differances, its been a couple years since i'v played with amp meters and heavy duty volt/ampage

 

Don't put in an Ammeter, they start fires easily. A voltmeter is all you need.

Voltage is like water pressure in a water hose, always there regardless if its flowing or not. Current is like the actual flow of the water through the garden hose. Current is what starts fires very easily.

 

With a regular ammeter, all the current has to flow through the meter. That's 120 amps or better under the dash. Not worth the fire risk and wiring needed. A voltmeter only needs a small sample off the switched circuit. If your system voltage is where it's supposed to be, the amps are doing what they do right.

If you really need an ammeter, you can put in a shunt resistor, which will carry the full current and develop a voltage drop across it in the order of millivolts. (thousanths of a volt) A sensitive meter remotely located and connected with light wire then reads that voltage, calibrated in amps.

This shunt, for instance will develop 100 mv output (0.1V) at 200 amps current. It is read by a meter that full scales at 100 mv and the needle points at 200 amps full scale. The big screws carry the heavy current. The #6 screws hold small terminals and wire that goes to the meter.

 

You can also get a Hall Effect DC current transformer that will produce the millivolt signal needed by your gauge.

The Hall Effect CT will be a wrap around device like a typical CT used on AC circuits, except the Hall Effect requires a small external power source.

That way you just unhook a cable, slip the CT over the wire and make your connections. You wouldn't have to create new terminations and additional splice points like when using a shunt.

http://www.offroadengineering.com/me...ts-Catalog.pdf

This company makes what you need. I've never used them before and can't comment on their product.

You should be able to use about any gauge you wish, you just have to scale things correctly.

For instance, using the shunt example above, you have a gauge that expects to see 100 mv at a full scale of 200 A, you should obtain the Hall Effect CT that will produce the same 100 mv at 200 A.

If I were going your route, I'd pick the gauge I wanted, confirm that full scale reading of XXX amps occurs at 100 mv or 50 mv (the manufacturer says they can do either), then contact the guys at the link above and see if they can accommodate you.

It'll take a few phone calls or notes but you should end up with a better solution than using a shunt. Fewer splices and terminations are always good, especially with the amount of current the systems on these trucks pull.

 

Good discussions on gauges but no one has answered his question yet.

The short answer is voltage is how much -- amperage is how fast.

You can have 12 volts in a wire but it won't go anywhere unless it has amperage to push it there.

Think of it as water in a hose, it won't go anywhere until you open the nozzle, and then it will get there only as fast as the pressure behind it will push it thru the hose and nozzle.

 

Voltage is actually the potential to move electrons = the higher the voltage the further electricity is able to jump or arc or overcome resistance.

Amperage is actually the amount or volume of electrons flowing or moving threw a circuit or jumping an arc.

Amperage does not push it. Think about the spark jump in a distributor rotor to cap or at the spark plug is that a high amperage circuit = no. Is the spark driven by high voltage = yes

Think about it in an electric welding application (arc, mig, tig) the higher amperage setting or hotter the arc or weld used then the more (higher volume of) electrons are consumed which = the higher your electric bill will be because you have used more of them which equals amperage.


So in the water hose example pressure would be = to volts and the water flow or volume would be gallons moved or consumed which would equal amperage.

The water hose will also only flow so much and is more dependent on the id of the hose for volume because at a certain pressure you will be unable to increase the flow no matter how much you increase the pressure to it.
In other words the id becomes the regulator of volume.

 

biltit explained it very well

 

well i dont want to catch another rig on fire ...guess ill stick with a volt gauge ...

 

uh...

 

Ya gotta put it in Chaisquatch terms.

Voltage bites.
Current burns.

 

j martin I will have to remember that one