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Amp meter reading

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Torino

Under normal conditions without any lights on what should be the normal reading on a system that is working properly?

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WH nut

Depends on the state of charge of the battery, but it should always be on the plus side

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rmaynard

Mine jumps from -10 to +10 when running at normal operating speed. However, the battery still maintains a good charge. :confusion-shrug:

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Save Old Iron

Depends on the state of charge of the battery, but it should always be on the plus side

Remember the ammeter only shows what is being drawn from or resupplied to the battery.

If the current draw from the ignition system and lights can be supplied by the stator, no power will be drawn from the battery.

The only time a battery should be noticeably discharged is when the tractor is started. The ammeter should show a charge when the voltage output of the regulator is greater than the voltage at the battery. Once the energy used by the starter motor is replaced back into the battery, the ammeter should read very close to zero.

Also note where your ammeter needle points when the tractor is turned off. That reading represents your true zero charge. If the needle points to a -1 or -2 amp charge when turned off, that is the mechanical "0" of the ammeter. This is where the needle will point when the battery is fully charged.

I have seen fully functional electrical systems show what appears to be a small but continuous negative reading if the mechanical zero of the ammeter is off. In the opposite, a mechanical zero at +2 or +3 when the tractor is off would give the impression the battery was always charging when in fact it is not.

Edited by Save Old Iron
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squonk

What if say their was a problem somewhere that was causing a 2 A draw with the key off. That would cause the needle to read on the discharge side and that wouldn't be the mechanical 0?

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Torino

Mine is at 0 when off and barely past 0 when running.  If I use my lights it goes about a quarter in to negative.  This tractor is not used often and when it is not run for a long time, maybe 15 min so the battery may not be fully charged at all times.

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Save Old Iron

Mine is at 0 when off and barely past 0 when running.  If I use my lights it goes about a quarter in to negative.  This tractor is not used often and when it is not run for a long time, maybe 15 min so the battery may not be fully charged at all times.

 

Well sir,

 

time to get out the voltmeter and check the battery voltage with the tractor running. If the voltage is less than 13.6, the battery will not be charging and will show a discharge when running.

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Save Old Iron

What if say their was a problem somewhere that was causing a 2 A draw with the key off. That would cause the needle to read on the discharge side and that wouldn't be the mechanical 0?

 Good point. This could be possible....

 

as much as the opposing scenario where a mechanical zero may be at 2 amps on the gauge and a 2 amp parasitic drain when the tractor is off would make the ammeter read zero !!!

 

gotta love all the one off possibilities in troubleshooting.

Edited by Save Old Iron

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Torino

At the battery it was jumping between 13.5-13.7.  If each mark on the gauge  is an amp, the needle with the tractor off is between 0 and 1 amp.  It is the same with the tractor running.  It never shows more than that while running.  It will go into the negative when I turn the lights on so it must be working.

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Save Old Iron

T,

 

you never mentioned which tractor model this is happening on. It sounds like the regulator is BARELY charging the battery.

 

We need to know if the tractor is charged by a starter generator or is if has the stator / rectifier regulator charging system.

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Torino

Well, I was kinda keeping it a secret. :)  It is a 78 Simplicity 7012.  It has a rectifier/stator.  I should of mention that.  I was  posting something else on the site the other day so I figured while I was here I would post about this.

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Save Old Iron

No problem with me. I enjoy all the different meats in a garden tractor stew.

 

Standard stuff here T.

 

Since everyone will shout out "check your grounds !!" we should get that over with right now (as to why everyone believes only ground wires develop bad connections, I don't know). Check the terminals on the RR and the terminals that connect with the RR for any obvious signs of corrosion. As always, run a separate ground wire from the aluminum case of the RR to the battery negative terminal. See if that one simple step helps the RR supply the correct power to the battery.

 

Charge the battery and make sure it has 12.6 volts present. If you have a shorted cell, it will never charge properly. Do a load test on the battery. Poor mans load test is leaving the lights on for an hour or so with the engine off. Should not discharge the battery below 11 volts. If you have a load testor - use it to confirm battery health. Another option is to monitor the battery terminal voltage while cranking the engine. Battery voltage should not drop below 10 volts.

 

You are most likely dealing with a Kohler 12HP so I assume you will have 2 wires coming from the stator heading to some configuration of a Rectifier / Regulator unit tucked somehwhere in the hood tower. Since the unit is charging - but seems weak - I might start off by checking the AC voltage out from the stator. Place a multimeter in the AC volts mode and connect one lead of the meter on each of the stator leads entering into the Rect/ Reg unit.

 

Normal AC output at full throttle should be well above 32 volts AC. Anything less than that will not allow the RR unit to put out 14. something volts to charge the battery. You appear to only have 13.6 volts which is BARELY enough to keep the battery charged. PLUS, the voltage at the battery must be dropping off when you turn on the lights since the ammeter is dropping into the negative.I'm assuming you don't have half a dozen airplane landing lights attached to the tractor !!!

 

So, either the regulator is shot, the stator is not supplying enough voltage (burned windings on stator), or the wiring associated with the RR needs attention.

 

I would

1/ trickle charge then load test the battery.

2/ jumper the aluminum RR case directly to the battery negative terminal and try running again.

3/ check AC ouput from the stator - if low , do a visual on the stator for burns / shorts

4/ dig into the wiring to the RR further - don't forget the ignition switch could be corroded too.

5/ replace / substitute the RR unit.

 

Let me know what you find.

Edited by Save Old Iron
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Save Old Iron

unless of course this tractor has the wimpy 3 or 5 amp charge systems. I really don't like the way those systems make a fool of me every so often. hopefully you will find an external RR unit and not just a black taped over lump ( 3amp diode) in the stator wires.

Edited by Save Old Iron

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