Blocking Diode Question

Discussion in 'Diode Installation' started by DonMcJr, Jan 13, 2011.

  1. DonMcJr

    DonMcJr WindyNation Engineer

    I have a PMDC 90 Volt @ 1750 RPM's and 5 amps. It's going to be connected to two 12 volt batteries that powers an inverter that powers a Video Camera. I'm also going to have a 15 watt solar panel in the system.

    My Charge controller is a Coleman Air Diversion Controller Model C160M (sorry your charge controller doesn't have a volt readout or battery status indicator and I ain't smart enough to add them to yours but I did purchase my dump load resistors from you). The instructions say if you are using a dc wind generator you may need a Blocking Diode. So do I need one for the Wind Generator or Solar panel?

    My understanding is this diode only lets current flow one way to prevent discharging of battery at night from the solar panel and prevent discharging if there is no wind on the wind generator.

    Do I have this right? I'm just learning and want to do it right....THANKS in advance.
  2. windyguru

    windyguru WindyNation Expert

    You got it right. The solar panel most likely already has a diode installed by the manufacturer so you do not need to add one.

    You can get one of our 40 amp stud diodes for your generator: ... king-diode

    Put the diode in the positive wire in between the generator and the battery bank.

    There is a symbol on the diode that looks like this > (looks like an arrow)

    The arrow points in the direction of the current flow. So, the arrow points toward the battery bank and that end of the diode connects to the battery bank. The other end of the diode connects to the generator.
  3. DonMcJr

    DonMcJr WindyNation Engineer

    Thanks. I ordered 2 from you but where in Michigan could I find one today...any clue?
  4. dlmcbm

    dlmcbm WindyNation Engineer

    Radio Shack should have some but they wont be as high of amps. I think the have the square 25A rectifiers that will work. turbine to AC conection and the + to the battery.
  5. TomT

    TomT WindyNation Engineer

    Yes, Radio Shack stocks 25A 50v Rectifiers and I have mine wired like the picture I posted before.

    Attached Files:

  6. WindyFAQ

    WindyFAQ WindyNation FAQ Staff Member

    How much current do the blocking diodes consume and do they generate alot of heat?
    Will they continue to consume power even when idle?
  7. TomT

    TomT WindyNation Engineer

    The amount of current that the diodes consume would depend on how many amps are going thru them.
    I have never done tests on that. I have since gone to Bridge Rectifiers like the one Windy Nation sells.
    They get warm but never hot.
    They do not consume any current when the turbine is below the battery voltage.
  8. Minnesota

    Minnesota WindyNation Engineer

    The power dissipated is V x I. In a 3-phase bridge for a wind turbine, 2 diodes are forward biased at any given moment which is ~1.4V for 2 Silicon power diodes. The current is what flows to the load (i.e.:battery). In the case of the Windtura 750 at max recommended current of 40 amps sustained, the bridge rectifier will dissipate 56 watts (1.4V x 40A). Make sure it mounted and cooled properly!

    For solar, a blocking diode could be either Silicon (0.7V) or Schottky (0.15-0.4V). Multiply this by the DC current going to the charge controller to determine the power dissipated.

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