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Old 13th September 2007, 03:20 AM   #121
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Quote:
Originally posted by luka
Hi

What kind of beast for alternator do you have???

you were in 15 place? Or have I misunderstood this?

If motor is not capable of driving alternator at its full load, then yes you should change the field of it. But I don't see how, if you don't have alternator with external control
Luka,

I tried changing the pulley ratios and this worked well. Alternator runs slower, and the engine doesn't stall nearly as easy as with the factory 2.3875" pulley. Engine's pulley is a Ford 302 Crank Pulley (7"dia), mounted to a modified lawnmower blade adapter, for a ratio of 2.93:1. This means that 3600 engine rpms, the alternator was spinning at 10,500rpms! OUCH! With an aftermarket "underdrive" alternator pulley of 3.5", this ratio is reduced to 2:1, reducing the top alternator speed to a more manageable 7500rpms. I would like to reduce this even further to say ~ 1.75:1, giving a top speed of 6300rpms, just about at the alternator's required speed to generate the full 140A output.

Anyway, please give me feedback on the pics.

Steve
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Old 13th September 2007, 03:23 AM   #122
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almost forgot- pulleys for the engine and alternator were hard to find 'cuz I used serpentine belt & pulleys. These transmit much more torque than comparably-sized V-belts.
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Old 8th October 2007, 09:17 PM   #123
luka is offline luka  Slovenia
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Hi

Damn something I would like to have, but no where to put, but that shouldn't be problem . I think if you should leave it at 7500rpm, it is not that much for alternator to run at that speed all the time + better cooling, right?
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Old 8th October 2007, 11:35 PM   #124
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Yes and No. Yes, because more air passes over alternator's innards, but no, because higher speed means more heat produced.
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Old 9th October 2007, 05:22 AM   #125
luka is offline luka  Slovenia
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Hi

More heat is produced where?
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Old 9th October 2007, 09:49 PM   #126
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Paticularly, the Stator. As it produces more power, its I^2R losses go up. Although after reading my last post, I think the delta in power losses (heat produced) is not that much. I was half-asleep when I posted that one. zzzzzzz

I would like to do some re-working of the control panel, though. Maybe make it a little more hi-tech looking.

Update on batteries: I now have 280Ah of storage. A friend recently gave me a nearly-new 6T starting battery, rated at 110Ah. To bring it into perspective, six - 6Ts are used to start an M1 Abrams main battle tank. That' quite a kind of power!. So now I have 170Ah of deep-discharge energy storage-batteries, and 110Ah, (1050CCA) starting power! I'm loaded for bear.
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Old 9th October 2007, 09:50 PM   #127
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Paticularly, the Stator. As it produces more power, its I^2R losses go up. Although after reading my last post, I think the delta in power losses (heat produced) is not that much. I was half-asleep when I posted that one. zzzzzzz

I would like to do some re-working of the control panel, though. Maybe make it a little more hi-tech looking.

Update on batteries: I now have 280Ah of storage. A friend who works for the local power company recently gave me a nearly-new 6T starting battery, rated at 110Ah. To bring it into perspective, six - 6Ts are used to start an M1 Abrams main battle tank. That' quite a kind of power!. So now I have 170Ah of deep-discharge energy storage-batteries, and 110Ah, (1050CCA) starting power! I'm loaded for bear.
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Old 10th October 2007, 05:05 AM   #128
luka is offline luka  Slovenia
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Hi Steve

Abrams uses 6 batteries?! well it is big...Do you happen to know if it has one or more starter motors, and on what voltage do they run on, probably not on 12v sistem.

How much time does this generator of yours work, if tank is full and batteries all full too, before you have to do something?
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Old 11th October 2007, 02:13 AM   #129
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One starter, six batteries arranged in three sets of 2 batteries in series for a 24/28V system. Starter draws 1.5kA for about 30 seconds until the burner cans kick in.

As for my humble little setup, depending on the load being drawn, if it draws, say 500W continuously (w/o the engine), maybe it would last say, six hours. With the engine running, again at 500W, it has a 3/4 gallon tank, so I would say, 4-5 hours on the engine, and when it dies, the aforementioned six hours. so, about 10 hours, max. These numbers are approximatons, because I have never really tried to run it out to the max time/power. If I have a chance to soon, I will test it out.
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Old 11th October 2007, 05:29 AM   #130
luka is offline luka  Slovenia
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Hi

Wow now that is long time I think with so much power. Maybe you should lower speed to 6300rpm, probably save some fuel, which would give you several more minutes of running with engine.
Do you have option of running engine at lower speeds if demand for power is not big, even if alternator wouldn't be working at max current?
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