How PWM stepless dump load works

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How PWM stepless dump load works

Postby Toralfen » Fri Apr 28, 2017 3:13 am

I got a windturbine connected to a 300w hybrid wind/solar controller (no company brand) and a 12v batterybank. I've read that all windturbines need a dump load, and the manual says the controller has PWM stepless dump load, but not any specific info about that function.

How does this dump load function work? Is it a built in function? The controller does not have any dumpload outputs, only a regular load output. The controller is basically a big heatsink, and ive read that some chargecontrollers burns the excess energy to a mosfet? But i really want to know how all of this works..

thanks
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Re: How PWM stepless dump load works

Postby Gordon-Loomberah » Tue May 02, 2017 1:03 pm

If the loads and battery capacity are large enough, then a dump load is not necessary. I've run numerous wind turbine generators over the years, and never used a dump load.

However, if there is a risk of over-volting the battery, then yes a dump load is required, assuming there is no mechanical regulation- wind turbine braking, furling etc.

Non-branded controllers are generally going to be junk, so it is a bit of a risk to rely on them.

In your case the dump load should function to turn on a resistive load to regulate at a set voltage. If there are no terminals to connect a resistive load, then it will probably be inside the box- and will probably look a bit like an oven element.
If it claims to be PWM regulation, then it will be rapidly switching the load on and off, with a suitable duty cycle to regulate to the set voltage. Whether or not that voltage is suitable for your battery is something you need to consider if the WTG has a significant output capacity relative to your battery capacity and loads.
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