Wd45 ammeter

With an alternator you'd want a -60 0 +60 ammeter. Personally I'd install a voltmeter when using an alternator, but the ammeter will keep it looking somewhat original. Unless your ammeter is defective it should show a fairly high charge rate just after starting the tractor and then taper down to very little charge rate as the battery is charged up. With a fully charged battery an ammeter should show just an amp or two, which would almost look like zero on a 60 0 60 ammeter. A voltmeter should show around 14 volts regardless of the charged state of the battery.

If the alternator is only capable of producing 2 amps and the battery is discharged to 50%, I can assure you that your voltmeter will not be reading 14 volts.

If your ammeter is reading 2 amps, your battery may be charged or your alternator may be bad. You'll have to look farther with other equipment.

If you have a voltmeter you can see somewhat what your battery voltage is just by turning the key on. If you have an ammeter it might show a slight discharge, which probably won't tell you much. If you have a voltmeter and it shows less than 12-ish volts it means your battery is either run down or kaput.

If you know how to read a voltmeter it will tell you more than an ammeter.



Edited by DougS - 20 Aug 2018 at 5:39pm

If I remember right, the WD ammeters were black faced gauges with Allis-Chalmers in white on them.  And I think the WD45 were too.  My 45 has a black faced Niehoff ammeter with a back lite face... and it got the gauge when converted to Alternator 30+ years ago. 

Doug is right on. You get a short in the system and you have a late model Alternator up front doing the charging chores, doesn't matter what size instrument cluster you have, if there's a Ammeter in there and that load (short) ramps the Alternator up over the rating that Ammeter has, that Ammeter is the first to start cookin'. And, just take it from there till you get the Battery disconnected, cause there ain't gonna be much left. A fire under the gas tank and between your legs ain't cool. The solid state VR's in the newer Alts are very sensitive to load changes, and in miliseconds ramps the Alternator up. Alternators and Ammeters are like oil n' water. They don't mix well. Like Doug said, if you know how to read a Voltmeter, it can tell you a lot!  Pretty simple. Pretty safe...

Perhaps, Dave. Perhaps. Sometimes a sudden removal of a load from the alternator will cause an overvoltage spike from the alternator, which will cook the alternator. Today's cars use fusible links, which open more slowly and tend to prevent the overvoltage spikes. I'd recommend a fuse over nothing at all, but you do risk frying the alternator.