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BRAND NEW 300 WATT DIVERSION/DUMP LOAD RESISTOR FOR 12 VOLT BATTERY BANKS
(See our other ebay listing for dump loads designed for 24 volt battery banks)
(Copyright Windy Nation Inc. 2009)
This is a heavy duty, wire-wound, power resistor which is specifically designed to be used as a dump load for 12 volt battery bank systems. Each resistor is capable of dumping/dissipating 300 Watts at continuous duty making them perfect diversion loads for wind generator and solar panel systems.
As stated, this particular resistor has been designed to be used on 12 volt systems. Generally, charge controllers for 12 volt systems are designed to dump excess energy at around 14 volts. See the chart below to see how many Watts will be diverted to the resistor at a specific dumping voltage:
(Internal resistance of the resistor = 0.73 ohms)
(controlled by charge controller)
Current Through Resistor
Power Dissipated by Resistor
DO NOT EXCEED A DUMP VOLTAGE OF 15!
To protect your expensive wind generator, battery bank and alternative energy system from potential destruction, choose a dump load that exceeds the maximum output of your complete system by at least 20%. For example, suppose you have a max. power 600 Watt wind turbine and a max. power 400 Watt solar panel (600 Watts + 400 Watts = 1000 Watts total) hooked up to your battery bank. In this case you will need a 1200 Watt dump load to safely operate your system (20% more than 1000 Watts = 1200 Watts). These 300 Watt resistors can be wired in parallel to dump 300, 600, 900, 1200 Watts, etc. For the previous example, you would need four of these 300 Watt resistors wired in parallel to dump 1200 Watts.
Consult the following chart for how many Watts can be dumped as a function of the number of 300 Watt resistors wired in parallel (See photo section at the bottom of this listing for a diagram showing how to wire resistors in parallel).
# of Resistors Wired in Parallel
Total Power Dissipated (Watts)
Note: The following simple formula can be used to determine dumping Watts as a function of the number of 300 Watt resistors wired in parallel:
Total dumping Watts ≈ (300 Watts) x (# of resistors wired in parallel)
General technical considerations:
A dumpload serves two main purposes. First, it keeps your batteries from overcharging which will quickly lead to their destruction. And secondly, it keeps your wind generator under load when your battery bank is fully charged, which protects it from spinning wildly out of control. To accomplish both of these tasks, the dump load “uses” the energy created by your wind turbine (or solar panel) when the batteries are fully charged.
REMEMBER, A DUMP LOAD CAN ONLY PROTECT YOUR BATTERY BANK AND WIND TURBINE FROM DESTRUCTION WHEN USED WITH A CHARGE CONTROLLER! IT IS THE CHARGE CONTROLLER THAT DECIDES WHEN POWER MUST BE DIVERTED TO THE DUMP LOAD!
Battery banks and wind turbines are very expensive. When selecting a dump load it is important to consider its “real world” power dissipation potential and its reliability. These 300 Watt resistors are rated for continuous duty in outside temperatures up to 104 Fahrenheit in open air environments. Forced air flow (i.e. a fan) is NOT necessary to maintain their 300 Watt rating. Look at the photos at the bottom of this listing to see just how massive these resistors are. When you purchase these resistors, you can have the peace of mind in knowing they will not fail on you. Do not settle for a sub-optimal, small dump load.Remember, if it fails, you might lose your battery bank and wind turbine!
Installation: These resistors must be installed in a location where air can flow. If you decide to mount the resistor(s) in an enclosure, the enclosure must be very well ventilated. That is to say, your enclosure must have many holes or vents in it so air can move in and out of the enclosure.
These resistors “use” energy be converting it to heat. When these resistors are dissipating energy, their surfaces will be very hot.The resistors must be mounted on a heatproof surface and protected from accidental contact from people or anything else. You can mount them on a piece of metal with fire proof insulation behind the metal. Wire mesh can be used to enclose the resistors to prevent people or anything else from coming in contact with them. Wire mesh is a good choice because it does not block air flow to the resistors. It is the end user’s (AKA: you the customer) responsibility to make sure that the resistors are used safely and properly.
As a benefit, you can use the heat produced by your dump load resistors as a heater. This is a good use of this excess energy. After all, this is exactly how electric heaters work.
Itemweight: 1.5 pounds (0.58 Kg)
Windy Nation will in no way be held responsible for improper or negligent use of this product.
See Photos Below
How to wire multiple resistors in parallel:
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