Installing a AMP meter on tractor?

I installed a AMP gage on a my tractor and it stays around 0. The electrical system is in good working condition but when running the amp meter stays around 0 cranking it shows a discharge. I'm assuming this is a normal reeding since theres no load on electrical system exempt spark correct?

The AMP gage is installed in the main wire directly coming out of the alternator 12V.

Now realizing this it would seem a volt gage would be more beneficial correct?

Hi! Well, you should see some charge when running? If you turn on the lights (assuming you have them) you should see the needle move for a sec or 2.

The gauge needs to be installed in the line that feeds all power to the machine, so that battery is on one side, all demand is on other to work properly.

L.

Having the amp meter hooked directly at the alternator output is the wrong place and, if anything, will just give you false high readings.

To work, the amp meter needs show how much charge current is actually charging the battery after all other demands are met.

I wouldn't call a volt meter "better", but it certaily is easier to hook up.

(quoted from post at 19:04:22 12/30/10) Having the amp meter hooked directly at the alternator output is the wrong place and, if anything, will just give you false high readings.

To work, the amp meter needs show how much charge current is actually charging the battery after all other demands are met.

I wouldn't call a volt meter "better", but it certaily is easier to hook up.

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Thats what I whose wondering. I have everything powered directly from the positive terminal off battery. What would be required to wire it correctly? Would I have to separate all the wires on battery and hook them to the amp meter's output?

Charge output from the alternator output and all loads go on one side of the amp-gauge, and the other hooks to the battery postive. This way it only shows a charge to the battery when it's actually getting one.

I would guess your alt is not working. The way you have it hooked up , it would have to show anything coming out of the alt to charge the battery after starting which it is not doing. Check the voltage at the big stud before & after starting. Should be a difference of 2 or 3 volts.

Rod, for an ammeter to indicate the net charging curent INTO the battery or discharging current OUT OF the battery the ammeters SUPPLY side wires to the hot battery post while its other LOAD side wires to the genny/alternators output PLUS it feeds all loads such as lights or ignition.

Sowire one side of ammeter to the battery and the other side to the alternators output and (on that same terminal) you feed lights and ignition etc.

Hope this helps

John T

JD, BOTH the alternators output PLUS all loads like lights or ignition are on/fed from one side of the ammeter while on the other side the battery gets connected. That way the ammeter correctly registers the net charge current into the battery (charging) or the net discharging current out of the battery.

When replacing a genny with an alternator I often run a new 10 gauge wire (depends on current rating) from the alternators output up to the ammeter and a new 10 gauge from the other side of ammeter to the battery. As I explianed above, the wiring to loads like lights and ignition is fed off the same side of the ammeter that the genny or alternator wires to

John T

If everything is powered from the battery that current isnt going through the ammeter.

Wire the SUPPLY side of ammeter to the battery then on its other LOAD side wire the loads like lights and ignition PLUS wire the alternators output, then it will correctly register the net charging current flowing into the battery or net discharging current out of the battery.

John T

If your tractor is running and WORKING and starting, well just ENJOY the @^$*%# thing and don't OBSESS over the ammeter/voltmeter thing!

Simply a matter of economics, supply/demand,put it here/.

Unless I'm missing something, that is exactly what I already stated in slightly different words . .

"amp meter needs show how much charge current is actually charging the battery after all other demands are met"

As to wire size, 10 gauge wire is fine as long as it is protected. If somebody sticks on an alternator that can make 100 amps, and they've got 10 feet of 10 gauge wire hooked to it with no breaker protection, it can be a fire-hazard.
Much depends on the quality of the wire insulation, duration of high amps, and if open air or covered. Since tractors are often greasy and wires old, it's very easy to create a fire-hazard when adding an alternator.

It's also why many auto makers, when using amp-gauges, used shunt-wired units and NOT direct-read units. This cut back on the need for large wires in long runs.

I suspect some people don't realize the fire hazard potential and use 10 gauge wire since it's the largest many auto stores stock in small rolls. I doubt you'll ever find 10 gauge wire hooked up OEM on a car or truck alternator unless it's a tiny one. 4 to 8 gauge is more like it.

A Delco 10 SI or 12 SI can be capable of 100 amps.

Wire needs for a 10 foot "round trip" run. First number is wire ampacity and second number min. size with a 4% voltage drop.

100 amps = 0/6 gauge wire
75 amps = 2/8 gauge wire
60 amps = 4-8 gauge wire
30 amps = 8-12 gauge wire

4 gauge wire needs a 50-60 amp breaker.
6 gauge wire needs a 40-50 amp breaker.
8 gauge wire needs a 30-40 amp breaker
10 gauge wire needs a 20-30 amp breaker
12 gauge wire needs a 15-20 amp breaker

Excellent point as to wire size, thats why I said "I often run a new 10 gauge wire (depends on current rating)"

One needs to size the wire correctly or else risk overheating and/or insulation damage or even more hazardous situations. Of course, wire ampacity ratings depend on if the conductor is free air or enclosed and the type of insulation and temperature etc etc etc

Fun discussion, thanks as always, hope we help and dont confuse the non sparkies here

God Bless you n Happy New year now

John T

Thanks everyone for the help its working fine now.