c40 or dump controller

[greenkarson]

here come the questions again.  does a 24 volt 100watt aquair turbine need a dumpload controller? Or is a c40 controller enough? Iv only seen turbine hit 76 volts so far open load in mid spring when water was almost peek i think c40 is rated for 130v or so. if i need a dump load controller is the a economical prebuilt one availiable?

thanks

ps sorry about size or pic give up trying to resize

http://www.otherpower.com/images/scimages/12475/P1010105.JPG

[electronbaby]

I dont know why you are measuring the open circuit voltage of your turbine. You would normally connect the turbine directly to a battery bank with a blocking diode in series. The battery would then hold down your voltage to some where in the vicinity of your battery voltage. You would then use the c40 controller in diversion control mode to take excess energy from the battery when the wind in producing too much energy than your battery can tolerate. The controller in this sense, would be used to control battery voltage by applying a load to the battery bank when it deems necessary to accomplish this. It is all done with voltage set points inside the controller. You will need some form of resistive dump load, possibly a water heating element which will need to be sized appropriately for what you are trying to do.

The c40 controller is rated for use with 12v, 24v, and 48v battery systems. You would only use the controller in charge controller mode with PV.

After reading your post again, you may be talking about some form of water turbine. The same principals apply.

[ghurd]

Like Roy said.

Use the C40 in diversion mode.  It IS a dump load "controller".

Notice it 'controls' a dump load.  It does not have a dump load in it.

It needs an external load.

Power resistors are best for a dump load.  Especially in that system.  

It would not be good to try to save a Loonie by using light bulbs if nobody will be there for 2 weeks.  Hate to ruin the batteries over a burned out light bulb.

I recommend using much higher wattage resistors than necessary too.

The system could be in a situation to be dumping 100W for weeks at a time.

Might get a better understanding by reading this story,

http://www.fieldlines.com/story/2009/6/18/14139/1634

I have a few, new, very serious mil-spec power resistors from a canceled project that would be great for this.  Email me if you have any interest in them.

G-

[electronbaby]

I know you meant it, but you didnt specify for the original poster:

Higher wattage is ok.

The resistance value is critical for controller longevity.

:-)

[ghurd]

Great call.

It breaks my heart to tell someone their half-price ebay deal on a 150K 500W resistor is useless in a 12V system.

Breaks my heart more to re-explain why it will not dump 500W even though 500W is printed on it.

G-

[scoraigwind]

You can use a c40 as a series controller (as for solar) or as as dump load or diversion load controller.  I actually recommend you use a morningstar tristar instead as they are better.  

Maybe you can get away with the solar configuration but I do recommend you use a diversion load.  The resistance will be about 1 ohm for each 14 amps you need to dump.  If you need to dump 28 amps, use half of this resistance or 2@1 ohm resistors in parallel.

have fun