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Discussion Starter #1
Does anyone know or can find out at what rpm's the alternator is producing what amps? :unknown:


Mr. Moose
 

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I "think" its around 20 to 30 amps. Not very powerful but not many accessories either. It should produce max power just off idle.
 

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I "think" its around 20 to 30 amps. Not very powerful but not many accessories either. It should produce max power just off idle.
Close, but it is actually a 40 amp alternator. Theoretically,fuelhog is correct, and the alternator should be sized to produce full output around 2000 RPM (engine speed). It should be producing anywhere between 13 and 16 volts at idle, and possibly up to 18 volts at max RPM, however this is a bit difficult to calculate due to the engine RPM being reduced by the pulley diameter on the crank shaft, then increased at the pulley on the alternator. Both of these pulley's would need to be measured so the rpm can be calculated at the alternator shaft to conclude where min/max outputs can be achieved.
 

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Discussion Starter #4
Ok, so max charging is theoretically at 2000 rpm. Would this be true if I were to get the optional 55 amp alternator? I was hoping someone had a multimeter capable of checking over 40 DC amps? :drinks:


Mr. Moose
 

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Optional 55 amp?

I didn't realize there was an optional 55 amp alternator. I'll have lock that little tidbit of information in the back of my mind in case mine ever fails. I've never stopped to figure up my power usage, but I'll bet I could get close 55 amps with enough additions.
:mocking:
 

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Electrical additions?

What have you added or what are you thinking about adding that will require a larger alternator?
My sprayer has an electric pump. More lights. A cab with heat/blower and a windshield wiper would be nice someday. More lights. An electric fan for those hot summer days would be "cool". More lights. An inverter to run a power tool out in the fields. More lights.
 

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You can try and measure alternator output all you want but until you put a load on it you wont be able to measure the amperage out put. You will need to load it down and see if it reaches its max output at WOT.
 

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You can try and measure alternator output all you want but until you put a load on it you wont be able to measure the amperage out put. You will need to load it down and see if it reaches its max output at WOT.
Yes, this is certainly a factor as available torque and horse power to turn the alternator is relevant. Basically the electricity isn't "free" due to the hp requirement to turn the alternator.
 

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My sprayer has an electric pump. More lights. A cab with heat/blower and a windshield wiper would be nice someday. More lights. An electric fan for those hot summer days would be "cool". More lights. An inverter to run a power tool out in the fields. More lights.
Is it safe to say you want more lights?! :laugh:
 

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Discussion Starter #13
Yes, this is certainly a factor as available torque and horse power to turn the alternator is relevant. Basically the electricity isn't "free" due to the hp requirement to turn the alternator.
Actually, while it does take hp to turn the alternator, the amount required is small compared to the total output of the engine. If it used so much power that WOT had a hard time turning it, then the tractor wouldn't even move. If the alternator is not producing it's rated amps even at full engine speed, then either that alternator is bad or it has the wrong pulleys installed.

I was wondering at what engine speed the alternator produced its rated output.


Mr. Moose
 

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Heated seat!
I use mine with a full heated suit that I use for riding my motorcycle on those cools mornings. I beleive Gerbing is who makes them.
 

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Does anyone know or can find out at what rpm's the alternator is producing what amps? :unknown:


Mr. Moose
The voltage output of an alternator is a function the regulator. The voltage is directly controlled by the voltage regulator on the alternator and is not dependent on engine RPM. Concerning maximum amperage output, the amperage output of an alternator is totally dependent on how much load is placed on it. The alternator will only produce as much amperage that is needed based on the electrical load on it. Concerning the maximum rated amperage of an alternator. Every automotive alternator is designed around an amperage curve based on alternator RPM. Generally, most automotive alternators will develop max. amperage output at about 6000 to 7000 alternator RPM. Considering that most engines drive the alternator at a 3:1 pulley ratio, the engine RPM would have to be about 2300 RPM to turn the alternator fast enough to develop max. amperage output. This is why most system designers say you should figure up the maximum load that will be placed on the alternator and then size the alternator to handle this load at 75% max. amperage output. The alternator curve increases quickly to about 75% and then flattens out for the last 25%.
If you add lights, use LED bulb lights. They make lots of lumens of light and only require low amperage to operate.
 
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