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This dump controller in the RE Projects

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tytower

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I dont understand what this "dump resistor" is . Is it supposed to be the battery you are charging or is it something entirely different?
 
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I dont understand what this "dump resistor" is . Is it supposed to be the battery you are charging or is it something entirely different?

It's like it says, it's a 'dump load' - to prevent your battery been over charged you 'dump' excess power into some kind of load, essentially a big resistor. The value and size of resistor depends on the surplus energy you might have, but for a decent sized system I suspect something watercooled in a 40 gallon drum might be appropriate.
 
Well OK I understand that now.
Why would I want to do this .
My panels are producing all the time in the sun but when my controller turns the mosfet off no further current or energy can flow from the panel , It has a high enough voltage on the solar cells but I am not allowing it to flow.

It does no harm to the panels as far as I am aware so why a need to dump this to a resistor which then requires money to buy and install?
 
For PV you don't need a load dump. There are shunt regulators for PV that do nothing but short circuit panel when battery full charge voltage is reached (need a blocking diode to battery in the above schematic).

For a wind turbine you need to keep a load on alternator or wind may over speed the blades to destruction.
 
also a dump could be a suitable sized hot water element .
my dump for my mill is fencing wire coiled around an old fluresent tube light cheap and works great , will buy water element when my system is finished and i know correct size.
 
Inteesting shawn
How would that work -do u have it coiled around the outside like a choke ? or do u mean chicken wire or the like? Is the wire connected to the metal ends or contacts?
How do u calculate what is needed for ur windmill

Would this not be better called a dummy load ?
 
My old dump was 24 volt 50 watt light bulbs strung together this way you could add up the watts and get the right amount for your mill, trouble though i had a spike with an extra gust of wind (130k) and blew them leaving my mill unloaded!! i thought there had to be a more reliable way so i used high tensile fence wire wrapped it around a broom stick till i was dizzy then put it around the light tube it only touches the glass and the ends stick out for connection this has had between 15 and 40 amps continusly and just gets hot enough to take the zinc coating off but i have never seen red hot.
The dump should always be able to handle max power.
When i add my new mill to the system i will change the wire to number 8 (thicker wire) and i have no pv yet but when i have them i will add up all the combined power my system can make and build/buy a hot water element, so my dump is temporary at the moment but the fence wire is good!!
 
So the hot water element is immersed in water I suppose and takes whatever comes through. Didn´t know all that . Thanks
 
The dump resistor is load resistance, no value given. It could be anything that can handle a surge current. This circuit is merely a voltage monitor, much like over-inflating a tire waiting for the explosion.
 
Mmm
In fact what was not made very clear is that "charge" , voltage and current is dumped to ground via a load resitance of some kind . When Voltage exceeds 14V the device switches all current to ground via the load.
When Voltage drops to 13.4 V it stops that and the original circuit operates .

Similar operation to a Zenner so I suppose the load could be tacked on the end of a 13.4V zenner and all the previous circuitry would be not be needed if you could find a big zenner.
 
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