Amp meter inaccuracte on 1250

[powerpooch]

As far as the wiring size, its always better to have thicker than needed wiring than too small. Its a waste of money but when I have more of this 10 gauge wiring that I got for free than I will be using in the next ten years, I am not worried about that the cost.

Just so you are aware, running a thicker wire will actually help the charging system. It will have a lower resistance per foot, which will better supply power to wherever it is going. Less resistance will mean less amps drawn. In the greater scheme of things, a short run like on a lawn tractor isn't really going to do much though.

This is very common physics. What it will do though is allow the wire to carry more current in a dead short. In that case, its up to the fuse to cut the power before any damage happens. Unfortunately I have heard that cheap fuses aren't very accurate on their listed value, and will easily go over double their rated value. I suspect this may have happened since the amp meter should be able to handle 15 amps. Engaging the PTO when you have the lights on should draw around that much power in total, if not a little more.

But thank you everyone, I was hopping to repair the current meter, but I guess not.
Since its on the need to be replaced list, I may see about some creating fixing to it.

I do know I wasn't the first person to make a mistake like this, and I know I won't be the last. The smart thing to do would have been to put my multi meter to everything to understand how it works, but being lazy about replacing my dying multi meter, this is the cost I have to suffer for not being more careful.

If I ever get the amp meter apart, I will try to post some pictures.
I've been meaning to see if I can get the hour meter apart to change the lens.

That or just replace it. I saw the new meters have lights in them and are very cheap.

[powerpooch]

Originally Posted by ironman

Inside of every amp meter there is a built in resistance called a shunt. The shunt is there to protect the meter movement circuitry by dividing the current flow so that not all the current goes through the meter winding. It is a parallel resistance circuit.

Most likely you have fried that shunt. The meter is reading high because now 100% of the current is going through the winding. It may work that way forever or eventually the winding may burn out too, and if/when that happens your tractor will not start because the battery circuit to the key switch is open.

At that point you can jumper a wire across the two lugs of the amp meter (of course the meter won't work but tractor will run) or you can put a new meter in.

The shunt is potentially fine. The meter acts about the same as it always has, but I feel like the needle is probably on a spring that got over extended. That is my guess anyway for never having one of these apart.

[R Bedell]

You can disagree, but he is correct.

I disagree with your opinion.

The OP can do what ever he wants. It is his tractor, his time, and his money.

[J-Mech]

Ok powerpooch..... you have some flaws in your thinking, and obviously only partially know what you are talking about.

First off... I want to know how you know the shunt is "potentially" fine?

Second, your big wire is not going to.make a damn bit of difference seeing as how you didn't change the wire supplying the fuse, or the wire from the fuse to the switch. All you did was hook up a big hose to a little one. It has been my experience also, that cheap fuses blow sooner than a better one. Also, jamming a 15 amp fuse in a 10amp circuit can potentially overload the feed wire. Not real smart on your part.

Third, you are WAY off in what you think a set of lights and a PTO draw. Two 30watt lights draw 5 amps total, and the PTO might draw 3. I have 6, 30watt lights on my 1811 and run the PTO, and all that just does pull 15amps. (Tad over.) You need to figure your math again.

Last.... you seem to disregard some good discussion here. You asked, and got good answers. Why do you think you know more?? Are you an engineer?

[sir_lancealot]

Originally Posted by J-Mech

Are you an engineer?

I am 🤔😁

[J-Mech]

Originally Posted by sir_lancealot

I am 🤔😁

You be quiet.

(So everyone knows, I'll tell my little bro to hush up if I want. )

[Sam Mac]

[powerpooch]

Originally Posted by J-Mech

Ok powerpooch..... you have some flaws in your thinking, and obviously only partially know what you are talking about.

First off... I want to know how you know the shunt is "potentially" fine?

Second, your big wire is not going to.make a damn bit of differenceverything seeing as how you didn't change the wire supplying the fuse, or the wire from the fuse to the switch. All you did was hook up a big hose to a little one. It has been my experience also, that cheap fuses blow sooner than a better one. Also, jamming a 15 amp fuse in a 10amp circuit can potentially overload the feed wire. Not real smart on your part.

Third, you are WAY off in what you think a set of lights and a PTO draw. Two 30watt lights draw 5 amps total, and the PTO might draw 3. I have 6, 30watt lights on my 1811 and run the PTO, and all that just does pull 15amps. (Tad over.) You need to figure your math again.

Last.... you seem to disregard some good discussion here. You asked, and got good answers. Why do you think you know more?? Are you an engineer?

If what was said about the shunt is true, then yes mine is potentially fine. The gauge isn't moving more than it ever did before. It is always reading high. the zero mark is now on the high side, not where the zero mark is actually printed. The gauge moves the same way and the same amount as it always did, but rotated a little. Since the shunt is just a resistor to take away some of the power going through the windings, if I blew the resistor, more power would be going through the windings, which would also change how the gauge reacts to changes in the electrical system. Without the resistor, the system wouldn't read high when there is no current going anywhere.

Since you do not know exactly what I did, the fuse does actually have a larger wire, it also isn't the stock fuse holder right now. Everything in my circuit from the amp meter to the lights is now 10 gauge wire. Why not do this when I have a 50 foot roll just sitting around that I have no other use for. It also looks like the wire from the starter relay to the amp meter is at least a 12 gauge. That wire is feed by the battery cable, so no issue there. 14 gauge wire is fine for 15 amps on such a short run.

If you read what I said, I said on engagement, when peak power will be consumed. There doesn't seem to be any specs I can find on this but I wouldn't be surprised if it was at least double the running amps. Its not a real concern for the system because it is a very short period. The main issue would be the fuse blowing if you don't use a slow blow fuse or over size the fuse a little.

Yes I do disagree with anyone that says running larger wiring is going to cause problems. I could use a battery wire to run the lights from and it won't change anything except cost a lot of money and be a waste of space. I was not the only one to disagree with this point.

[sawdustdad]

Since we are comparing qualifications, I'm an engineer. A nuclear engineer no less. And I worked at a 2 gigawatt nuclear power plant, so I've seen my share of electrical gizmos.

Powerpooch is correct. Running a larger wire will NOT overload the charging circuit. It may increase charging current very slightly due to lower resistance in the circuit (even though the entire charging circuit has not been replaced) as he potentially shortened the amount of 14 or 16 gauge wire in the original harness.

5 feet of 12g + 5 feet of 16g has less resistance than 10 feet of 16g. Though the difference is so small as to negligible in this case when it comes to charging current.

The shunt is fine. It's capable of way more than the fuse is.

the meter's needle mechanism is damaged/bent. Replace the meter. Or not. Put a VOM on the battery to confirm it's charging and let it ride. It's a lawn mower.

[ironman]

Since I am the one who brought up the topic about meter shunts, I would just like to point out that in the OP's opening post after shorting out the power lead he said "I don't know if this event caused the amp meter to become uncalibrated, or if maybe I did something when I was struggling to remove the tiny bolt on the back of the meter. I just know that when I started my project, it was reading normal, and that when I finished, it is always reading high."

It wasn't until 3 posts later that he said " the zero mark is now on the high side, not where the zero mark is actually printed."

The second statement would have made things easier had it been said in the opening post. Judge Judy would not be happy with the defendant.