Ammeter vs volt meter on 12v converted system

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wayneyada

Junior Member
This is on a '50 shoebox woodie wagon. It's been converted to 12v but ammeter has been bypassed. Would like to either get it working or change over to volt meter.

So first question, any reason why the ammeter shouldn't work? I know I need to run wire loom backwards from the way it was since it is now neg ground. But otherwise?

Secondly, does anyone make a volt meter conversion or replacement that would fit in the same slot in the speedo cluster - and look somewhat normal?

Thanks in advance for your help.
 
I prefer a volt meter myself. Ammeters were fine in the day of generators and early alternators. Maybe pushing 45 amp. Today alternators are pushing close to 100 amp or more. Most amp gauges even most heavy duty are at 60 amp. Even semi's and heavy equipment don't run amp meters any more. Also with a volt meter there is generally no power going through it with key off. Some one else may know what will fir your dash. I usually put Stewart Warner under the dash. Just 1 wire to a hot with key on and 1 to ground.
 
Go with a volt meter. Much safer than ammeter if you develop a short.
Under dash fires are terrible.
 
wayneyada said:
This is on a '50 shoebox woodie wagon. It's been converted to 12v but ammeter has been bypassed. Would like to either get it working or change over to volt meter.

So first question, any reason why the ammeter shouldn't work? I know I need to run wire loom backwards from the way it was since it is now neg ground. But otherwise?

Secondly, does anyone make a volt meter conversion or replacement that would fit in the same slot in the speedo cluster - and look somewhat normal?

Thanks in advance for your help.
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Been using the original induction (loop) ammeter on my 12 volt conversion for a number of years with no issues. (go for it)
 
19Fordy said:
Go with a volt meter. Much safer than ammeter if you develop a short.
Under dash fires are terrible.
Click to expand...
Trying to understand this. Are you saying that volt meters don't have wires connected to them so they can't short??
 
Volt meters do have wires. Basically one to + and one to - The loop style gauge just has an induction wire going through a loop.
 
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I've always used the loop(induction) style ammeters with 12 volts and an alternator. Never had a problem as the wire passes through the loop and is not directly connected to the gauge,
 
34PKUP said:
Trying to understand this. Are you saying that volt meters don't have wires connected to them so they can't short??
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No. I just remember a short I had with an ammeter and it burned up my dash wiring. I could be wrong but, I been gun shy of ammeters ever since.
 
Check with Williamson's in Arkansas - they may be able to take your stock gauge and turn it into a voltmeter and have it look stock.
 
19Fordy>>>I just remember a short I had with an ammeter and it burned up my dash wiring. I could be wrong but, I been gun shy of ammeters ever since.>>>


Yep. I'm leery of ammeters too.


Voltmeters only need a very small diameter wire under the dash because they only need to carry a very small current for the voltmeter to operate.


Ammeters (loops or otherwise) need a very large wire because they need to carry very large currents under the dash even with generators.


If a small wire shorts under the dash, it usually melts or pops like a fuse and cuts the connection to the battery and generator.


If a large wire shorts, it usually doesn't melt but acts like a stick welder till there's a fire in full bloom under the dash.




Jack E/NJ
 
Can a volt meter be hooked up to any switch or other power supply under the dash as long as there is no power with the switch off,or are there some things to stay away from? I am putting a 12 volt meter on my 49.
 
Yes, voltmeters can be hooked up to just about any supply under the dash. And they use so little current, like a quartz clock, that they really don't have to be switched off. Jack E/NJ
 
Wayne, Jack E, sums it up perfectly in post #10 and #12. Most aftermarket wiring companies won't even supply the wiring for an amp gauge for safety reasons. If it's an antique car that was factory wired for an amp gauge then you don't have much of a choice. If it's a situation where you can rewire your car with a volt gauge, by all means do so. I would give Ron Francis, (a fellow Woodie guy) a call. He sell wiring kits and might have a suggestion.
 
Wayne, I probably should have looked for a Ron Francis Wiring catalog before I answered you, but I just found one. There is a 1/3 page article in the catalog explaining why you should never use an amp gauge. As I suggested above, give him a call.
 
38coop said:
Can a volt meter be hooked up to any switch or other power supply under the dash as long as there is no power with the switch off,or are there some things to stay away from? I am putting a 12 volt meter on my 49.
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If you really need one why not get one to just plug into your cigar lighter?
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They consume a bit more power than an analog voltmeter due to the LEDs. So it's best to have them in a switched cigar lighter if you don't pull them out. They also come with a usb port for cellphone, etc charging. Jack E/NJ
 
http://www.madelectrical.com/electrical-tech.shtml Thought this was interesting, section on amp gauges he focuses on Dodge but same principle on Ford. Had a Dodge Mini Winni long ago and had to replace harness after meltdown. Every electron passed through the amp gauge, charge and discharge. Was only maybe a number 10 wire, night driving, headlights, wipers, factory AC, cruise, etc. You get a built in campfire under dash.
 
wayneyada said:
This is on a '50 shoebox woodie wagon. It's been converted to 12v but ammeter has been bypassed. Would like to either get it working or change over to volt meter.

So first question, any reason why the ammeter shouldn't work? I know I need to run wire loom backwards from the way it was since it is now neg ground. But otherwise?

Secondly, does anyone make a volt meter conversion or replacement that would fit in the same slot in the speedo cluster - and look somewhat normal?

Thanks in advance for your help.
Click to expand...
Yes. Ford. go to a junk yard that has '70's-80's ford trucks with a volt meter. the guts of that voltmeter will fit inside the case for your ammeter. run a line from ign. sw to Vmeter and gnd. and good to go
 
The original induction -style guage on my 52 merc was broken but it had an aftermarket guage under the dash. I was able to remove the faceplate on the original gauge and install it on the aftermarket gauge. It fit in the hole in the cluster and I was able to make metal tabs to hold it in place that utilize the original screw holes.
Works very well.
Rob
 
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