Zero drain zero volt diode?!

[South Easter]

I rectify right at the stator, and run DC down the pole.  I would like to measure/monitor the generator output voltage, but at the moment I can only 'see' the battery voltage when the wind is low.

Is there a circuit to allow current to flow into the battery, but not in the reverse direction, and yet does not draw current from the battery?  I.e. it should be powered by the voltage from the generator, or just be unpowered if there is no wind.

Of course a diode would do it, but that means another 0.7V lost...

TIA

South Easter

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http://windpower.org.za

[drdongle]

Move the rectifiers off the tower and measure at that point.....other wise no unless you add extra circuits from the generator to carry the unrectified out put for measurement. Wireless might also be a possiablity.

[PaulJ]

  Why not run a second rectifier, in parallel with the existing one on the AC side? Of course, you'd have to run another pair of wires down the pole, but they could be very thin as they would only be delivering microamps to the voltmeter.

   Another thought, voltage of an unloaded alternator is proportional to RPM (assuming you're using some sort of permanent magnet alternator), so if you know your cutin RPM at a given battery voltage you should be able to infer the alternator voltage below this speed with some sort of tachometer or frequency meter.

   Paul.