Ammeter converting to voltmeter

I have a M with a bad ammeter and after reading some of the old messages, it seems the way to go is with a voltmeter instead. My question is, can I get a voltmeter that will fit in the same cutout and how do I wire up the voltmeter?

Anybody know a vendor that has a fair priced voltmeter?

I have Bobs pictured for wiring that back on the pannel, can anybody show me which/if any wires that need to be chenged?

Thanks

Simple--- Connect all wires that were on both sides of the amp meter into one connection. Put one small bolt through all and tighten it up. Tape, or shring tube tha connection as it is a "HOT" wire electrically.

Gauges are available at the right size. Put the gauge in and connect the same side to ground as your battery is grounded. Then connect the other side to the ignition switch wire going to the coil (if distributor ignition. If magneto, a switch will be needed to turn the switch on and off from the light switch power wire. Some gauges draw so little that they can be left on all the time. then connect it up to the light power wire with no switch. JimN

Its your tractor and your call as for what gauges you install, however for no more then the cost,,,,,,,,,ease of installation,,,,,,,,,conforms to originality n looks correct n satisifes "Correct Police",,,,,,,better indicator of actual charging system operation,,,,,ID PERSONALY PREFER AN AMMETER.

My reasons are the voltage is like 12.6 volts setting but at fast RPM if shes charging good the battery voltage only rises to like 13 to 14 and a lil over AND THE RESOLUTION AND METER MOVEMENT IS NOT ALL THAT GOOD AND INDICATIVE AS THE INFORMATION AN AMMETER CAN PROVIDE IN MY OPINION

Am ammeter, however, would read dead center setting,,,,,,,,swing to - discharge even if only a few amps of discharge occurs,,,,,,,,,,have good resolution when running from like a few up to 10 to 20 amps of charge at fast RPM AND JUST PROVIDES MORE DETAIELD MORE PRECISE ACCURATE INFORMATION OF WHATS HAPPENING IN MY OPINION VERSUS A LESSSER RESOLUTION VOLTMETER.

A slow discharge (like a minor high resistance short) wouldnt hardly if at all be even noticeable on a voltmeter and shes gotta be at decent fast RPM to raise battery voltage to 14.2 etc but thats NOT as readable on a gauge then an ammeter that has a full easily observeable needle swing from - 20 to + 20 (0r 30) amps charge.

That slow few amps discharge (to run battery down if she sets several hours) is very noticeable on an ammeter but not near as noticeable/readable on a voltmeter cuz a few amps trickle discharge on a battery dont drop the voltage down much (if at all) from the normal setting 12.6 volts

OKAY RANT IS OVER LOL its your call and Jim has told ya how to wire it up but give me an ammeter any time on the old tractors (THEY JUST ARE RIGHT N LOOK BETETR LOL) and I can easily observe its neelde n tell you much better the charge or discharge rate n whats really happening VERSUS that voltmeter which is more for modern autos with alternators

Best wishes, either will fit in slot n will work if thats your preference.

John T (NOT any Correct Police buttttttt believe an ammeter is much better)

John T – I agree 100%! For monitoring operation of old tractor electricals an ammeter provides much more useful information than does a voltmeter and thus is preferred.

Besides.....a voltmeter just looks out of place in an old tractor panel!

AND since we BOTH agree its just gotta be right ya think lol

NOTE Im always careful NOT to criticize anyone elses choices as they have put their hard earned money n sweat in a tractor they are rightfully proud of and who am I to criticize it HOWEVER that dont stop us from posting what we believe in our hear of hearts (or the Correct Police) is good n often correct useful information I figure

JT

Thanks guys. The tractor gets pretty light use so it will likely be here till they carry me away feet first and after that, I really dont care what the new owner thinks of what I did to it. I just want it to be functional for ME.

It is converted to 12 volt, negative ground with a "modern" 1970s 10-SI alternator from a GM car so the "correct police" issue is an issue that is already done. Sure its correctable but not by me, I bought it this way and it will stay this way, I am not investing more to switch it back. I would like to switch the alternator out for a smaller import alternator so the hood fits nicer but knowing me, that wont be done till the current alternator fails.

So knowing I have a more modern alternator in a 12 volt system, is it still the recomendation to just stay with a ammeter? The explanation for a ammeter makes sence, I cant for the life of me find who or why it was recomended to go with a voltmeter. If an ammeter is still the better way, I will go with that because I can grab it off the shelf at tractor supply or similar and then I dont have to look for a voltmeter that fits the control box. I dont want to mount it anywhere but in the box, mostly for protection from the elements but some for appearence and for lazyness.

Thanks again.

Hey John T and Bob M,

Add another one to the list in favor of an ammeter instead of a voltmeter.
I also think it gives a better indication of the battery's state of charge. With that being said, with the HUMONGUS 100+ amp alternators they are putting on cars and trucks now, a 60 amp ammeter might blow and would not even wiggle when the ignition was turned on. LOL

Leonard, retired EE with 33 years teaching electronics at a 2yr tech school and 50+ years farming!

Yes indeed Tractorman! A voltmeter tells the operator virtually nothing about a battery’s charging rate (also to some extent it’s relative charge level…) as it’s being charged. A suitably scaled ammeter however indicates this very nicely.

Incidentally one of our older Kenworth farm trucks came with BOTH ammeter (150-0-150 amp range!) and voltmeter installed in the dash. This is the ideal setup for monitoring electrical system operation...