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Tractorholic
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300 Posts
Discussion Starter · #1 ·
Does anyone know at what RPM the alternator starts to re-charge the battery? I bought a new Interstate battery last Saturday with 625 CCA and she needed to be charged this afternoon. There wasn't enough juice in her to turn the engine over fast enough to start. Been playing with the MF12 a bit but not running it for any length of time and not running her at very high RPM. So I'm wondering if it's not re-charging because of that or if I have a magneto problem. :anyone:
 

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Elf guardian
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7,712 Posts
Hey Ross.
Have you downloaded the Tecumseh service manual?
It walks you through the tests to determine what might be wrong.
 

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Tractorholic
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300 Posts
Discussion Starter · #4 ·
Sometimes I can be a little slow on the up take. One of our girls (Newfs) went into labor, She's not contracting well so the wife just left with her for the vet's. Emergency C-Section. Cha-Ching. Coulda bought a couple more tractors for what this is gonna cost me!! (LOL) I will down load the manual tomorrow. Thanks again

Ross
 

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Elf guardian
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7,712 Posts
rossboyle52 said:
Sometimes I can be a little slow on the up take. One of our girls (Newfs) went into labor, She's not contracting well so the wife just left with her for the vet's. Emergency C-Section. Cha-Ching. Coulda bought a couple more tractors for what this is gonna cost me!! (LOL) I will down load the manual tomorrow. Thanks again

Ross
Yeah, I hear ya about that Cha-ching. Hope the newf does well.
I think I mentioned to ya in a pm, that my eldest daughter is in vet college.
With my wifes dog habit, and my tractor habit, I think I might be alright.
I'll pay my daughter tractors to fix the dogs. What can she say?
 

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Tractorholic
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300 Posts
Discussion Starter · #6 ·
Just don't part with the MF7. That one is soooo sweet!
 

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Tractorholic
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300 Posts
Discussion Starter · #9 ·
The manual doesn't say. However, it does call for all charging tests to be done at engine speeds of 2500 rpm and higher. My Harley doesn't charge until above 2500 rpm which is why I was asking.
 

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Super Moderator
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14,167 Posts
Does the tractor have an ammeter? That should show you if it is charging or not. Sometimes it is a bad connection at the regulater module or a bad ground connection at the engine or the regulator chassis. Sometimes the regulators are faulty. Get the Tecumseh manual as noted above and you should be able to determine the problem.
 

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Electric Tractors
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5,639 Posts
An easy way to tell is use a digital volt meter,
Start the tractor run at idle, take a reading
Rev up to full speed 3600 or so and take another reading.
if the voltage rises it's charging.
 

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Tractorholic
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300 Posts
Discussion Starter · #12 ·
I have a digital meter. Where should I take the reading?
 

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Super Moderator
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14,167 Posts
Does an MF12 have an ammeter? I assumed it did because my 74 MF8 has one. My regulator was not working when I got the tractor.
 

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Tractorholic
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300 Posts
Discussion Starter · #16 ·
Hi Brian, Yes it does have an ammeter. I'm just not sure that it is working properly. I have one on my 7 that I may swap out to see if it works.
 

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Tractorholic
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8,369 Posts
Just wanted at add to what was already said. As a quick check on pretty much anything that charges , car , truck , GT, ect. I'll start by checking the voltage before starting , should be around 12.5 v , if the battery is good it shouldn't drop below 9.5 v when cranking , as soon as it starting the voltage should rise above 13.5v at high idle . If it's not then the battery really isn't going to charge . I'll turn on everything to load up the alt. , headlights, PTO , ( on vehicles 4 ways a/c ) and see if the alt will keep up the voltage . If the battery is old or bad you might not see 13.5 v at idle until a long time running. On one of my cars that I don't use often is going to need a new battery it cranks slow and when it starts you can hear the alt trying to charge the battery , like a winning noise .The dash gauge is on the low side until you run it for a while . The alt is full load which isn't good for it. Here's a cheap handy tool , it's an inductive amp meter you can lay it across the battery wire and check how many amps it charging and also checks how much draw when starting.
K D Hand Tools Danaher Group KDT 2423 - Current Indicator
 

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Tractorholic
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8,369 Posts
Neat little piece. The scale is a bit bigger than I need, if my battery is pulling 600amps, I'm running!
Me too !!! But you might see that if the starter is shorted or engine locked up . Then you would know it wasn't the battery !!
 

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Tractorholic
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300 Posts
Discussion Starter · #20 ·
Engine starts, but starts kinda hard. Which is whyI have to give the battery a little boost. I'm wondering now if the drive belt isn't disengaging properly when depressing the clutch brake pedal causing unnecessary drag on the engine. It's sitting down in the pulley quite a ways. The belt looks pretty old so I'm going to replace it with new today and see if that makes a difference. (yes all pulleys are turning free and the idler is working correctly) I will also check all my grounds before re-connecting the battery.
 
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