I put an ohm meter across my amp gage terminal, it shows no continuity, is this correct?

How can I test this gage?

As my amp gage does not work because it is not hooked up. I have been told that the large 10ga red power wire to the battery should go in series here to each terminal, it seem like a lot of wire for a little amp meter. Also if no continuity is through the meter, I take that it will not work.


I now have all my other gages working! Thanks to everone for all of their help!

Bryan

 

Mine is hooked up between the alternator and the Fuse block. Although everything works electrical wise, I don't really read anything on the gauge. Does anyone know if I should be reading anything when the lights are on and the a/c blowing?

James

 

James,

Just wondering exactly how yours is wired up? When you say Alternator and fuse box. Is it in series.

Bryan

 

Some one told me that I can use any +12 wire comming from the fuse box, hook it to one side/terminal of the amp meter and connect the other side/terminal of the amp meter to ground.

Will this work or is it a fire waiting to happen?

Bryan

 

[updated:LAST EDITED ON 20-Jun-02 AT 07:34 PM (EST)]better get ready for a fire
I think if you did that you would burn it out. you would have a dead short.
You want to show the charge going to the battery,not to a ground.

I have a 51 Ford with a 12 volt Generator. The wire goes from the battery terminal on the regulator thru a loop on the back of the guage then to the terminal on the starter solinoid with the positive cable from the battery.
What year truck do you have? Do you have a wiring diagram.

 

My truck is a 1952, I ran the same wire to the gage, mine has 2 terminals not a loop, so I had to cut the wire as instructed and install in a series, turn on lights, shows a charge, I reverse it now shows a discharge, all seems ok until I try to start, will not turn over. I crimed the wire back togeter, all is OK, just no amp meter.

I checked the gage with an amp meter, no continuity. Is this correct or do I need a jumer wire between the terminals on the amp gage?

No wiring diagram, is there on online any where, I do have the shop manual, it is not detailed enough.

Bryan

 

I believe there are two different type gauges. The gauge with the loop that the wire passes through must be inductive. The type with the two connections requires the wire from the battery to the alternator to be connected to the two leads on the gauge.
Are you sure that you have no continuity across the gauge, it may just be a very high resistence to keep the current flow down. Try either using the Auto range on your meter or turn the meter to a higher resistance range. If you still have no reading at the highest resistence setting then it sounds to me like the gauge is bad.

 

Brian,

Did you check the gauge with an AMP meter or an Ohm meter? The meter should be set to measure Ohms not amps.
If the meter deflects when the lights are switched on then the meter is working.
If you jumper across the gauge leads you eliminate the gauge from the circuit so I don't think this is the solution.
Sounds like you may need a second wire from the battery to the fuse box.

 

[updated:LAST EDITED ON 21-Jun-02 AT 10:54 AM (EST)]Yep, I ohm'd it out with a digital Fluke meter, set to auto. Thats what I may need to do, run a second wire from the battery to the fuse box, just for the meter.

Can you buy to loop type amp meter for a 52, as that would be an easier and neater installation?

 

Brian,

Without getting into the details too much I hope I can help clear things up a little. tgregoire is on the right track. There are several different ways to sense the status of your charging system.

An inductive meter allows the current to flow through a wire straight past the meter and on to the fuse block or wherever your load is connected. This type of gage uses a loop or several loops of the wire carrying the current to produce a magnetic field which the gage innards measure. This type of gage generally won't have any terminals to connect wires to since the current flow is sensed through the magnetic field and not measured directly.

A second type of gage will have a large strap (usually brass) between the terminals on the back. The strap is called a current shunt and is intended to be kept with the gage although it could be removed. You hook one wire from the battery to one terminal and another wire to the electrical load. The strap is carefully made and matched to the gage so that almost all of the current flows directly through the shunt and only a small percentage flows through the gage and produces a reading. If the shunt is still in place, this gage will have a very low impedance (resistance) if you try to measure it in with an Ohm meter. Without the shunt, the gage will have a very high resistance.

A third type of meter doesn't measure current at all but measures voltage. Most modern vehicles I've seen use this type and they indicate that if the voltage is below about 11.5 V or above about 13.5 V you have a problem. With this gage you connect one wire from the battery to the + input and ground the - input so you read the system voltage on the meter. The gage will have a very high resistance if you measure it with your Ohm meter.

I've done a quick sketch to show the different ciruits. The bottom line is, don't connect a gage with a low resistance in parallel with the battery and don't connect a gage with high resistance in series.

https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=5829&.jpg


I hope this helps and doesn't just confuse things for you.

George

 

Awesome,

Thanks for the help, I just dont know what kind of gage I have now. I have the feeling mine is missing the shunt. Has anyone ordered a new one out of Obsolete Ford Parts? I am wondering if it comes with directions for the type of gage they send you?.

Bryan

 

Great diagrams Earl. I'm impressed. I thought I'd throw my two bits worth in. The ammeter is in series with all the loads coming from the battery EXCEPT the starter. (If the starter was also in the current loop the ammeter would need to read 600 amps and it would be hard to tell you're discharging 1/2 amp.) One side of the ammeter, regardless of it's type, should be conected to the same post of the starter relay as the heavy -6V cable coming from the battery. (assuming 6V pos ground.) Keep in mind that all the truck's current (except the starter) will pass through this wire so it should be 12 or 10 guage. Mine's 10 guage red. ('49 F1) The other side of the ammeter should be wired to the common post on the circuit breaker block, or fuse block. This common post is also connected to the voltage regulator "B" terminal. From the other side of the circuit breakers, current is sent everywhere else in the truck.

With all that said, when DISCHARGING, current will come from the battery (via the starter relay post), through the ammeter to the circuit breakers and then to whatever is running: heater, lights, horn, ignition. (Maybe not the horn?) When CHARGING, the current will come from the generator to the voltage regulator and to the circuit breakers and to the loads. Any excess will go from there through the ammeter to the battery (via that starter relay post).

If the ammeter reads backwards, simply trade terminals.

Both wires to the ammeter are basically unprotected so grounding them could cause a fire. Protect them well where they come close to metal surfaces. Their normal insulation is very adequate for 6 or 12 volts, but if it gets cut or worn and ground out, you could be in trouble. My wiring harness is well wrapped in tape.

I hope this helps. Good luck,
Johann

 

I have got it all figured out now, I dont think I have the shunt, to allow current to flow throught my meter. Can I just make one out of 10 gage wire and some connectors?

 

It's pretty tough to get the shunt just right so the current flow through the shunt and the flow through the meter are balanced. Shunts are available from various sources like Radio Shack (shudder) and Newark Electronics. They are usually rated with a maximum current they can handle and a number that tells you how much voltage will appear across the shunt for each Amp running through it. For example, the optional shunt for my meter says "1 mV / Amp, 15 Amp continuous duty, 30 Amp for 15 minutes". The problem you'll have is finding one to fit your meter terminal dimensions that has the right rating.

Hmmm, I suppose you could make one out of some 1/4" x 1" x 6" brass alloy 360, part number 8954K337 from McMaster-Carr at www.mcmaster.com, $2.29 plus shipping. Cut it to length so it's just long enough to cover the truck meter terminals, clean up the ends, and drill two holes for the terminals. Hook up a battery, the truck meter with shunt installed, a calibrated ammeter, and a headlight bulb all in series. Then just drill small holes in the shunt between the terminal holes until the truck meter reads the same as the calibrated ammeter. Voila! As long as the brass doesn't get hot (and it shouldn't) at full output from your charging system you should be all set.

Remember, this is just my opinion and is worth every penny you paid for it! ;-)

George

 

I believe Earl is correct in that you probably have a shunt type meter. But you could buy an aftermarket amp guage in the parts store that does not require an external shunt. It would be hooked up the way you tried originally by cutting the wire in two and installing the guage in series.