Diode / battery

[edy252]

hi all.....

are the diodes used only to rectify the current from a wind genny? or are they also used to prevent taking power from the batteries? i mean, if we get a larger bank of batteries, should we get bigger diodes??

thanks in advance

[wpowokal]

edy252, yes diodes are used to rectify the Ac from some wind turbines to DC.

They are also used to prevent current flowing from batteries to wind turbine (say in the case of a tape drive motor(TDM)which is a DC machine and does not need diodes to rectify from AC) as without a blocking diode (non return valve) current would flow from batteries to motor the turbine when the wind was not blowing.

The current rating of your blocking diodes is relevent to the source(current) comming into the batteries, not the size of the batterie bank. You don't need a diode between your batteries and the load.

Hope this helps.

regards Allan

[Opera House]

The sailboaters actually have a bump switch that allows them to start spinning the prop by the battery when they only have light breezes to overcome inertia.  Many of them don't even use a diode but a reversing switch when it is mounted fixed to the mast.  They flip the switch depending on the direction of the wind.  Guess they like to do everything hands on.

[Nando]

The diodes should have a capability of at least 3 times the PEAK charging current and a reverse breakdown voltage at least three times the peak output voltage of the generator.

Also, make sure that the diodes have the proper Heat Sink, otherwise they will mmmmmeeeeellllt.

Regards

Nando

[LEXX]

Would using diodes be cheaper than a bridge rectifier?  What about voltage drop, would it be approxamately the same?

LEXX

[drdongle]

Voltage drop for a single rectifier is about .7 volts for a bridge 1.7 volts

Carpe Vigor

Dr.D

[drdongle]

Sorry thats .7 and 1.4

Dr.D

[Opera House]

I often use the square bridge rectifiers with that wonderfull mounting hole in the center and pins that accept 1/4 inch push on connectors.  Great for testing.  Much easier to use because the case is electrically isolated instead of having to fool with mica washers and stud insulators.  Just use it as a single diode by connecting the two AC terminals together and you get more current capacity.  A matched length of wire to each AC terminal will help balance the current.  This doesn't give you as much current capacity as you would think but that is made up by the much higher currents these blocks are rated at.

[Ungrounded Lightning Rod]

A pair of diodes per AC wire IS a bridge rectifier.

The blocks you usually think of as a "bridge rectifier"

are just an assembly of four diodes, suitable for two

AC lines.  Use one and a half of another to make a three-phase

bridge rectifier.

Because of higher production volumes, bridge rectifier

assemblies in common sizes may be less expensive than

buying four diodes of the same rating, plus a heat sink,

and building one of your own.  But the difference isn't

great.  Whether you find it cheaper to buy assemblies or

individual components will depend on your local parts

availability.

[Nando]

Lexx:

One diode, two diodes make bridge, 4 diodes make a full bridge.

One diode drop, two diodes drop and two diodes drop per device.

The two diode bridge is used when the AC has a Center tap.

The full bridge is used when the AC does not have a center tap

One diode for half way rectification

Two diode and 4 diode full bridge for full wave rectification.

Regards

Nando