# ampmeter or voltmeter



## camaroz (May 30, 2011)

I am rebuilding/refurbishing my 1983 MTD lawn tractor and I am not sure if the amp meter is working or not. I am guessing not since I did not see any movement on the guage when the tractor was running. I am thinking of replacing it with a volt meter, so I need to be educated in this swap. Not the actual swap but in terms of advantages of keeping an amp meter vs switching to the volt meter. 
To me the volt meter tells me as much information as the amp meter plus it gives me the status of the battery.
Would anyone like to respond?

BTW, Happy Canada Day and happy Independence Day!


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## john walsh (Sep 25, 2010)

*Voltmeter vs ammeter*

Camaroz,

I agree a voltmeter seems the better choice. By turning ign to "on" w/o starting, you can check state of charge of battery (should be about 12.6 Volts in fully-charged bat). If you want to know when you exceed charging system capacity, simply note engine off voltage vs engine running voltage. Engine running voltage should be about 13-14 volts without a load and voltage will get lower as load increases. When you are lower than the engine not running voltage (open circuit voltage) you are in a discharging state. If your alternator or generator stops working, you will note a less than OCV even w/o a load on electrical system.


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## Country Boy (Mar 18, 2010)

You will have to rewire the unit if you want a volt meter. In an amp meter, the current from the battery to the switch is run through the meter, thus showing the amperage both drawn from and put back to the battery. In a volt meter, you want a positive lead from a terminal that's hot when cranking and running on the key switch and a negative that goes to ground. That way, you will get battery volts, but won't drain your battery with the meter. You may or may not have a terminal on your switch that is hot when running and cranking but dead when the key is off. If your engine has a fuel solenoid on the carburetor, you could draw off the feed for that.

Do not just hook a voltmeter in where the amp meter hooked up. You will most likely fry the meter, or it simply won't be accurate because it will be trying to read the voltage difference between the two wires, which will most likely be zero or close to it. You will most likely need to connect the wires that came from the amp meter together to keep the circuit active (not entirely sure on this, you could try it without connecting them).


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## camaroz (May 30, 2011)

I have to rewire the whole system anyways, mostly due to the fact the machine is almost 30 years old. That is why I was asking this question, if I have to rewire I might as well use a voltmeter.
I was thinking of putting in a accessory outlet (cigarette lighter style) so I can add my solar panel to trickle charge the battery when I am not using the tractor. 

I am interested in hearing any comments on the voltmeter/ampmeter or even the accessory outlet.

Thanks


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## jhngardner367 (Apr 5, 2011)

I have BOTH,simply because the amp meter will show if there's an abnormal draw,and the volt meter shows how quick it's drawing.If the amp meter suddenly shows a draw,when you're not using a high-draw accessory(ie,a pto),something just drew a ground(shorted out)Most amp gages won't move while running,only during a high draw,such as starting,lights,short,or pto operation.On one tractor I had,the ampmeter did this,and I looked at the volt meter,and it showed a discharge= alternator shorted.


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## camaroz (May 30, 2011)

I have room on my dash so I think I will add a matching voltmeter next to the amp meter. Best of both worlds then. Thanks all.


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