Will welding fry an ammeter on a tractor?

[CurlyDave]

You will be far better off if you replace the dead ammeter with a voltmeter. An ammeter really doesn't show you the condition of your battery, a voltmeter does. And the voltage tells you if the battery is charging far better than any ammeter.

Best of all you don't need to run heavy current through your meter.

 

[weedpharma]

Depending on the type of meter movement, you may have a shunt to carry the heavy current and the meter movement shows the voltage across the shunt and displays it as Amps.

I would expect the ammeter to be centre zero reading to indicate charge and discharge. This would require one side of the meter to be connected to the battery and the other to be connected to the load and alternator. If the engine is not running and lights turned on, it would read negative. When the engine is running the meter would show the net difference between the load current and alternator outout current. If the alternator is putting out more current than the load needs, the meter would show positive (assuming the battery is not fully charged).

If the lights are working, then current is flowing from the battery via the meter. If nothing is showing on the meter, it may be a shunt type meter and burnt out. Disconnect the meter and check the resistance. If very high resistance (I assume it is a mechanical meter rather than digital) I would suspect the meter. While it is disconnected see if the lights work. This would indicate it is a shunt type meter.

Weedpharma

 

[rsallen]

Did I read right?
Before he started having problems he said the amp meter normally read in the 30 amp range all the time. No that can't be right, I must be confused, if the battery was charging constant at 30 amps it's cooked.
I can't imagine an tractor having or needing a 30 amp load while running.

 

[streamin]

I have been welding on vehicles for years and the only time I disconnect a battery is if I'm close to the computer(for a car). I have heard that you can fry one but I never have. IMO, it wasn't from the welding but you never know.

 

[ovrszd]

I think weedpharma best described his situation.

I'm also pretty sure, unless it's been upgraded, his tractor is running a generator. The meter shows charge when the engine is running. Sits at 0 when engine off. Shows discharge if load exceeds generators ability or if generator isn't working. Also pretty sure he's got an external regulator.

I too have welded on a connected system a LOT. Never had a problem.

It's almost like there's a separate problem with little to do with welding. In those old systems the regulator is usually the culprit. I've removed the lid and sandpapered the connections on a regulator to make it work if that happens to be the problem.

 

[yomax4]

Never hurts to do a double ground when welding on anything with meters, motors and computers. I just clamp an extra ground lead to an earth ground or something separate from what i'm welding on. May not be needed but doesn't hurt. I welded on an ATV frame once and blew the winch auto reset fuse..

 

[super55]

Thanks for the tip weedpharma I'll give it a shot next time I get back to the tractor.

I can't say for certain it was pushing 30 amp but I know it was at least 20 according to the gauge. The tractor is a 1957 and I have only owned it for a few years now and I'm not sure if this was initially a 6V to 12V conversion not that it should matter anyway and the alternator looks fairly new and really looks like a GM style alternator so a voltmeter might be a better option to go.

To be honest after it happened I was pressed on time and didn't have time to pull the dash and run a test light or v-meter to check voltage yet but I do appreciate everyones input. I welded, snowblowed in 8 deg weather for a few hours while having the headlights on, noticed the gauge wasn't working, parked it, shut it off and turned it back on to see if the battery was drained and would crank slow. It started fine and lights never dimmed so I presumed it was still charging and then had to leave town for work.

Next time I wrench on it I'll check dcV at the ammeter to make sure I have V in and out of the gauge if I do I think my other multimeter come to think of it can do dcA if I connect it in series up to 15 or 20a so I'll give that a shot to see what happens.

It shouldn't be too difficult to troubleshoot was just some fellow advice to see if welding will typically blow out an ammeter.

 

[ovrszd]

You might have been hit with a fluke current flow due to welding that hit your gauge.

Your tractor has definitely been converted. Would have been 6V with a Generator and external regulator when built.

As described by someone earlier, you'd get more value now from a Voltmeter. When vehicles changed to alternators they also generally changed to voltmeters.

I think you are still charging, just not registering it on the gauge anymore.

You got yourself a great tractor there. My neighbor had one when I was a kid. He'd hire me to mow hay with a 3pt mower. I loved running that tractor. I was accustomed to a 641 Ford. Lot better gear selection on the Oliver. Seemed easier to handle as well. Course I was just 10 years old.

 

[super55]

You might have been hit with a fluke current flow due to welding that hit your gauge.

You got yourself a great tractor there. My neighbor had one when I was a kid. He'd hire me to mow hay with a 3pt mower. I loved running that tractor. I was accustomed to a 641 Ford. Lot better gear selection on the Oliver. Seemed easier to handle as well. Course I was just 10 years old.

Thanks,

I love my old Oliver. Honestly it is probably the best 2500 dollars I ever spent. It's quite a tractor for its age. For food plotting my kubota sits at home now. That old gasser's exhaust just sings when it's out in the fields. I absolutely love it when it gets under load and the governor opens a little and gives it just a touch more gas.

 

[crazyal]

Honestly, unless you really like the look of the meter I wouldn't replace it. I would measure your battery voltage before turning anything on, should be about 12.6 volts and then start it up and remeasure, you should see the voltage go up about 1 volt to about 13.4 volts. You can do the same test with your headlights, should be a little brighter with the engine running but the multimeter is the better way. Like CurlyDave said, a volt meter will tell you everything you need to know and because it doesn't need to be wired in series (in-line) it's much less likely to cause you electrical problems down the road.