charging problems... help

Discussion in 'Windtura Generators' started by ddoyal, Oct 25, 2009.

  1. ddoyal

    ddoyal WindyNation Engineer

    I have a set of hyperspin 5 blade 28" on a GE dc PM 1/2 horse motor. On test stand, with nominal load, this motor would produce 18 to 20 volts @ 9 amps in 15 mph winds. After installation, and being connected to battery bank (much larger load), this same motor is only producing 12 to 14 volts @ 3 to 4 amps. My battery bank is taking FOREVER to recharge and never reaches 14.5 to 15 volts.

    Now... I do have a 2hp pacific scientic 14.5 amp 120 volt dc continuous charge motor. Will this motor solve my problem?
  2. windyguru

    windyguru WindyNation Expert

    Actually, your results to not sound that bad!

    To answer the simple question, your GE DCPM motor's voltage is not going to exceed the voltage of your battery bank. So, that is why the voltage is measuring around 12-14 volts.

    Now the reason you are not seeing higher amps to your battery bank can be for a variety of reasons. But if you are seeing 3-4 amps from a DC PM motor this is not horrible. Here are some reasons why:

    1. You are using a PM motor as a generator. They are not as efficient as brushless 3-phase AC alternators but they are pretty darn good.

    2. What is the wind speed that you are seeing 3-4 amps? And more importantly, what is the wind speed that the blades are actually experiencing? The power in the wind scales as the wind speed cubed. 15 mph wind has 3.38 times more power than 10 mph wind. So a 3-4 mph mis-measurement in your wind speed, could be the answer to your problem. Maybe the wind at your blades is only 9-13 mph and not 13-17 mph? There is almost 7 times more power in 17 mph wind compared to 9 mph wind!

    3. And yes, it will be harder for the blades and generator to spin when hooked up to a larger load compared to your test stand load.

    4. There are also other reason but I will stop here.

    There also might be some overlooked mistake like a short or something is wired incorrectly. This is probably not the case but it is worth double checking.

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