Hot Rods Amp gauge coversion to Volt meter?

Is it possible to convert an amp gauge to a volt meter?

 

I'm interested in this as well. I've seen people gut them and install the voltmeter behind the factory face, but I'm curious to if there is another way.

 

I attached a links below that show how to wire an amp and volt gauge. The amp gauge shows current flow direction, charging vs discharging and the volt gauge shows how much juice you have running the electric system. You could wire up an amp gauge as a volt gauge (I guess) , but I don't know how you would "read" it.

https://www.google.com/search?q=vol...v&sa=X&ei=yfBuVbTcJca2sAWd2oHgCw&ved=0CB8QsAQ

https://www.google.com/search?q=amp...VeyvFoaYsAWa44CYDQ&sqi=2&ved=0CB0QsAQ#imgrc=_

 

Generally, yes. But, you have to know a few things about your panel meter.

http://www.allaboutcircuits.com/textbook/direct-current/chpt-8/ammeter-design/
http://www.allaboutcircuits.com/textbook/direct-current/chpt-8/voltmeter-design/

http://www.allaboutcircuits.com/textbook/direct-current/chpt-8/kelvin-resistance-measurement/

 

I would think that the internals of the meter would have to be changed, in addition to changing how it's wired into the circuit. A volt meter is connected in parallel to the load and the amp meter in series.

 

Generally speaking, people swap out a voltmeter movement and switch faces, etc. What are you working on?

 

If it's a shunt type ammeter, you can convert it BUT you'll need some pretty accurate instruments to select the right parts and to calibrate it. If it's an inductive type (pretty common on older cars), no you can't. The inductive type can be identified by the fact that most don't have an actual electrical connection on them; they'll have a metal 'loop' or channel that the wire goes through and they 'read' the magnetic field around the wire.

 

Don't know if you can convert an amp gauge to a volt meter but I do know you can convert one to an incendiary device with a one wire alt and pulling too many amps. LOL

I would think that the easiest and cheapest way would be to take the guts from a similar size and sweep volt meter and install them in the amp meter.

 

Which is why ammeters have fell out of favor.... LOL

 

Well I know for a fact that me and Fireball Roberts don't like 'em.

 

I sort of converted one on a similar truck years ago. It had a 3 wire Delco alternator, and they're pretty reliable, so I just did away with the meter, and replaced it with an idiot light. just takes a little bit of metal work.

The ammeters on 50s chevy trucks are inductive, they are not shunt type, By the mid 60s they were using shunt type.

 

Yes I have a good mechanic friend that's adivising me NOT to use the amp gauge. Because as you said it may burn up the whole car at some point. I'm running a generator also

 

I doubt converting an ammeter to a voltmeter would be very successful but finding a voltmeter that could be adapted to the panel should be doable.

 

Italian Panteras used ammeters with no shunts. The ammeter would carry the load most of the way thru warranty...then act as a fusible link.
I recall more than five, and referring to the syndrome as 'the Pantera problem'.
Italian Forenza had the same problem, early on.

 

If you're running a generator, an ammeter is fine. Most generators only put out 30 amps (the BIG car units only go to 50) so the fire hazard is low as long as the wiring is sound and sized right (#10 wire). And generators work differently compared to alternators, so an ammeter actually gives a bit better indication of charging system health if you're running a generator. It's when running a late-model alternator (most of which can easily put out 70 amps or more) that running an ammeter gets spooky. That kind of current can produce fire/smoke in large quantity and #10 wire will be a welding electrode...

 

A shunt type ammeter is actually a voltmeter, but it measures very low voltages, and is a centered movement that will measure both positive and negative voltages. It is basically measuring the voltage drop and polarity across the shunt. Converting one to a typical voltmeter is possible, but likely not prudent.

An ammeter is as safe as a voltmeter if the wiring is done correctly. I agree that adding a bunch of accessories and a high-output alternator to a system designed to just have lights and a cigarette lighter is a recipe for disaster.

The following is also true: Adding a bunch of accessories and a high-output alternator AND REPLACING THE AMMETER WITH A VOLTMETER on a system designed to just have lights and a cigarette lighter is a recipe for disaster.

Removing the ammeter and installing a voltmeter, without any consideration for the original intent of the system wiring, should not calm your fears of having an electrical related fire.

 

I'll note that full flow ammeters get a bad rap because people just hook them up without being serviced. They gain resistance over time, lose magnetism, etc. If properly serviced and wired correctly, an ammeter can provide you with a lot of information about your charging system that a voltmeter cannot.

 

What's involved with "servicing" an amp meter?

 

You might want to check out this guy. He primarily does 60s up Ford gauges but could possibly provide advise to you. rccinnovations.com

 

incendiary...Beaner I'm impressed, you spelled it right and I still can't pronounce it!!

 

Find a voltmeter movement and replace the ammeter with the innards and face from voltmeter. If you are putting a big alternator in, make sure the wiring is in good condition, especially from alternator to battery.

 

Running a generator with basic original accessories No high power draws

 

I Know what pork

Oh yes, porknbeaner, I also had one incinerate it itself
at night and shut down all electric power on my shrimp
boat while having nets out and many other boats in the area!
A cloud of smoke and that burning wire smell is no fun at all
on a night with rough seas. A jumper across the wire running
through the switch and I was able to restore power and lights!
All volt meters after that incident.

 

A lot of good info.

 

Best way to convert an amp gauge to a volt meter.

 

Why would you do this in the first place? Just curious. Sounds like making an apple out of a banana. Not trying to be a wise ass ( really).

 

Because I'm running a 70amp alternator and i didn't want to have a car-b-q because of a 65 year old gauge.

 

The age of the gauge isn't a problem. The capacity IS. A 70 amp alternator is a bit (a LOT, actually) too big for a 40 amp ammeter to handle. It'll act like a fuse if the battery's too low and the alternator's running full tilt to recharge the low battery.

You won't burn up the whole car. It'll just pop like a fuse and you'll, effectively, disconnect the battery from the rest of the vehicle wiring (except for the battery cable to the starter which will be useless because you won't have any juice to the start terminal on the starter when you turn the key)

Go through Hemmings. There's guys converting ammeters to volt meters by replacing the movements and silk screening new face plates to match the rest of your instruments .

The ammeter should match or exceed the capacity of the alternator or you should switch to a volt meter (or have your ammeter converted to a volt meter and put BOTH original ammeter together and tape them up. Run a wire from the ignition switch, through a 5 amp fuse to the positive side of the volt meter. DON'T try and connect the volt meter to the voltage reducer you're using for the stick fuel gauge because it'll show you the output of the voltage reducer, not the state of the battery/charging system.

 

So my conversion has been done for a few months now and is working perfectly. Really feel better about not having all my electrical loads running through the old gauge.

Adam

 

You can also reduce the shunt resistance so more of the current flows through the shunt and therefore reduces the reading on the ammeter. The numbers on the ammeter are no longer correct, but anyone that knows how to read an ammeter doesn't really pay attention to the numbers, but rather the deflection angle of the needle. You know what is normal and what is not based on that deflection. And reducing the shunt resistance is easy.