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Brettw

Power draw

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Brettw

I have recently installed a fan / defroster in the snow cab of my 7118. The engine in this case is a 18 horse Kohler Magnum, hence the 7118 that isn't really a model number. Anyway, I bought the fan / heater because it was about the same price as a stand alone fan, and can be run on fan only mode. I have it wired directly to the battery with an in-line fuse. When the tractor is running and the heater portion is turned on, the Amp gauge on the dash shows a draw of about 15 amps. Is this too much of a load on the Magnum stator? I am not so worried about the battery being drained down a bit, as the use of the heater would only be occasional and for short terms, but I am concerned about damage to the charging system.

Thanks to all of the electrical Gurus in advance.

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ReedS

All depends on the rated output of the alternator, if it's a 15 amp alternator it's going to be working at it's max output. Ok in short usage times not good for long running useage as it will likely run hot and eventually burn up.

If it's a 30 amp unit I wouldn't get that excited about it as long as your using wire that will handle the amperage.

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BLT

Here is where a voltmeter could tell the story as how well the the system voltage is being maintained. Also a spec number of the engine would tell you what stator and regulator you have which should be traceable.

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CleanBee

By design your tractors regulator will limit the amp draw from the charging system so it will not overload anything.

The only way it will overload is if you manipulated something or if the regulator is defective, otherwise the system will just work as hard as it was designed for.

If the battery is being drawn more than being charged, well you know...

Dan

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PhanDad

Carl,

I thinking what Brett means is that when the heater is turned on the ammeter shows a "charge" 15 amps to the battery. That would be the draw of the heater.

If the heater were wired via the normal tractor wiring (terminal board or accessory position of the ignition switch), then the ammeter wouldn't change with the engine running (assuming the engine charging system can supply enough amps). Without the engine running, the ammeter would show the heater draw.

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Brettw
quote:By design your tractors regulator will limit the amp draw from the charging system so it will not overload anything.

The only way it will overload is if you manipulated something or if the regulator is defective, otherwise the system will just work as hard as it was designed for.

If the battery is being drawn more than being charged, well you know...


id="quote">
id="quote">

Thank you. That's what I needed to hear. I doubt very much the "defroster / heater" would be used much at all. Last year, there was only a few times where I realized I couldn't see well because of the fogging up of the inside, and that was after clearing snow from a number of neighbor's driveways. The fan should take care of that and I believe I will have very little need for the heater part of it. It's nice to have, but I doubt it will be needed much..........unless it's extremely cold out. 63 on Monday here.

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CarlH

Bill,

Still confused. The ammeter current charge/discharge represents the net electrical current load of the tractor on the battery. If the added defroster is indeed wired directly to the battery, it should not be a part of the ammeter indication.

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PhanDad

Carl,

You are correct that normally the ammeter shows the net electrical current load of the tractor on the battery IF all the electrical users are connected through the tractor wiring. So if the heater was wired into the normal tractor wiring and the engine was running when the heater was turned on, the engine charging system would supply the current to the heater and the ammeter wouldn't move. If you continued to turn on lights, an electric PTO, use an electric lift, a some point the current draw would be greater than the engine could supply and the ammeter would deflect negative.

But with the heater wired directly to the battery, when the heater is turned on with the engine running, the only way the engine current can get to the heater is through the ammeter, thus showing a positive current flow to the "battery". In effect the battery is providing the current to the heater and the engine is "replacing" this current to the battery.

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HubbardRA

I think you are both slightly off on the way it works. If the fan/heater is wired directly to the battery, then the only thing that will show up on the gauge is the charging current going from the engine to the battery. This may not be the full load, since the regulator will limit the current flow from the generator/alternator. The load on the battery can be greater than the charge seen on the gauge.

If the fan/heater is hooked to the terminal block, the gauge will show only the difference between the load and the charge, because that is all that is going through the gauge to the battery. The load is taken from the charging current before any current goes to the battery. If the battery is fully charged and the generator/alternator can produce enough to compensate for the load, the gauge will not move. If the battery voltage is pulled down some by starting or such, it will show charge till the battery is fully charged. If the load is more than the charging system can handle, then the gauge will show discharge.

What the gauge shows is always dependent on which wire it is hooked into. If you also hooked up a volt gauge to the battery, then you could tell exactly what was happening throughout the circuit.

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timflury

The charging system is designed to operate at full output. The voltage regulator controls the demand for current to the battery. That being said, if the current being pulled from the battery while the heater is turned on is greater than the output of the charging system, you will be discharging the battery. You will not cause any damage to the charging system, only the battery.

It would be a good idea to wire in a voltmeter to keep an eye on the battery when running the heater. When the battery voltage drops below, say 12.7ish, the battery will be discharging. Try not to let it get below 10 volts, and let the system recharge after you are finished using the tractor.

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