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Alternator question

Started by EZ, August 16, 2004, 05:37:53 PM

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EZ

I put a single wire alternator on my mill and have a switch to shut it off just in case I need the extra power for sawing. Now that it is ready to use I'm now wondering if it will hurt the alternator by just running idol.
EZ

Fla._Deadheader

  You can burn out the regulator if you don't have the output voltage going somewhere. Why not let it charge the battery??? If it is not needed, it will regulate itself and not use hardly any engine power to turn it ???
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

Stump Jumper

I dont think  that will be a problem electricly speeking if your switch is off
Jeff
May God Bless.
WM LT 40 SuperHDD42 HP Kubota walk & ride, WM Edger, JD Skidsteer 250, Farmi winch, Bri-Mar Dump Box Trailer, Black Powder

Fla._Deadheader

  I did the switch thing with an import car alt and the switch. Burned out 3 regulators ???

  Rebuild shop put me straight. Them regs cost $40.00 EACH. ???
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

D._Frederick

EZ,

Check with the alternator manufacture about running it with out a load, some brands can be run without a load without blowing. Running with a full charged battery will not take much torque to turn the alternator.

Tom

My LT40HD has, I think, a 120 amp alternator, and there are more problems with running the battery down than losing sawing power.   I've never noticed the alternator dragging the motor down but I have had stop sawing while the alternator caught the battery back up.   Electric over hydraulics are heavy power consumers.

NewEnglandTreeSvc

Quote You can burn out the regulator if you don't have the output voltage going somewhere. Why not let it charge the battery??? If it is not needed, it will regulate itself and not use hardly any engine power to turn it ???

Dedhead is dead-on. Older machines with "Generators" and mechanical regulators could be run without a load with out damage. Alternators cannot. Without an electrical load to regulate itself, an 12v alternator is capable of developing several hundred volts in the windings and diodes. The diodes themselves are rarely rated for more than 50PIV (peak inverse voltage- alternators pruduce AC which is rectified by the diodes into DC- unlike generators which produced DC). A single-wire alternator, even if "switched off" can develop enough eddy current by spinning full-speed to self-activate; by switching it off, you're eliminating the reference voltage the regulator uses to control field current.

You get more load from mechanically spinning the alternator than by the electrical load. When the system is fully charged, alternators run at "idle" current; the field is energized just enough to run the ignition system. If the motor has a meganeto, than there's no electrical load once the battery has reached fully-charged.

If that fractional load imposed by the alternator makes THAT much of a difference, you have other problems.
Erik Lovell, Arborist


EZ

I had the starter and batt. hook up for about two weeks now. I've been starting the motor with it with out the alternator mounted. In the pass two weeks I never put the batt. charger on to charge the batt. so I imagine the batt. was pretty low. Yesterday when I got the alt. hook up and started the motor, I notice the motor was idoling lower than usally. I only ran it for a minute before I shut it down, cause it was supper time. ;D
The main or most draw on the batt. will be when I load a log on the mill with the winch. I wonder how long it will take to charge the batt. up after it's loaded. I alternator is a 73 amp.
Thanks for the last answers.
EZ

VA-Sawyer

EZ,
    Don't worry about how much the idle drops due to charging load. Engines  have almost no spare horsepower at idle speeds. They need it all just to keep running themselves. Another thing to remember, is that power is a function of speed. The faster the altenator turns, the less torque it needs to produce the same amperage output.  My debarker pulls about 60 amps when running. I can't tell any difference in feed speed if I engage the debarker during a cut.  The Ampmeter jumps from barely charging to almost pegged when I throw the debarker switch on.  
I also think having the inline switch will prove fatal to your altenator.  
VA-Sawyer

slowzuki

IIRC you can run an alt with no battery connected but don't go connecting and disconnecting when running.  Causes huge voltage spikes.

Ken

EZ

So I should turn the alternator switch on before I start the motor and leave it on until the motor is off, right.
EZ

Tom

That sounds like taking the switch off would be the best thing. :)

EZ

Me and key switches dont get along very well. Even if I had a blue print on how to wire it up it would still would be wrong. I put a separate off and on button for the motor and a push button for the starter. When I went down and got the alternator, the same guy at NAPA waited on me and ask if I was going to put a key switch on it and I said no. He said I needed a separate switch to shut off the current from the alt. cause it would drain the batt.
EZ

Tom

You're not alone on key switches.  I have a neighbor that can just hook the wires up sight unseen and the  thing will work.  If I haven't labeled the wires from the old switch then I can't seem to get them back where they belong either.  The same thing with drum switches.. There must be some secret we haven't discovered.

My old alternator was wired through the amp light on the console.  I thought it was just to have an idiot light but, OH NO!   One day the light burned out and the alternator quit charging.  That's when I found out that the light was tickler for the alternator.  I put a little resistor in the line and everything has been ok since.  

Just when I think I know it all ........... :D

EZ

If you find out the secret, let me know, will ya.  :D :D
EZ

Quartlow

If its a single wire alternator you don't need to switch the power on and off to it, wire it hot. Otherwise you need a switch rated for the same amperage as the output of the alternator.

GM alternators can be wired hot all the time, In fact both the ones on the 880 oliver and the wd45 allis are wired hot they have never drained the battery
Breezewood 24 inch mill
Have a wooderful day!!

Fla._Deadheader

All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

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