DC Resistor Air Elements

One of these air resistor elements can be used on 12 & 24V battery systems to divert surplus power up to 1kW to air heating. Two of these air resistor elements can be used together on 12, 24 & 48V battery systems to divert surplus power (up to 1kW each) to air heating. Two resistors (0.8 and 1.0 Ohm) can be combined in many ways as per table below.

The power dissipated in a resistor is calculated as follows:

• (fully charged battery voltage)^2 / resistance

Also check that the maximum current draw does not exceed 30 amps, this will depend on the size of SSR used (we have assumed a D1D40).

• Current =  Power/fully charged battery voltage

Power in Watts (table below for 0.8 & 1.0 Ohm):

For our 10 and 40 ohm resistor options, you can connect these resistors together in a wide array of series and parallel ways to get a range of resistances. Using 1-3 elements in this way you can get: 3.33, 5, 10, 15, 20, 30, 40, 50, 60 Ohms.

Such resistors are helpful for clipping upper voltages on wind and hydro turbines when used with suitable MPPT regulators. This is achieved by programming the AUX relay via an SSR to connect the resistor to the generation DC voltage when an upper limit is reached. For example the AUX relay “PV trigger” function in the Outback FM60/80 MPPT regulators.

Power in Watts (table below for 10 & 40 Ohm, single resistors >1000W will need fan cooling):

Please note: All resistors must be mounted on a steel backing with suitable protection to eliminate any fire risk or electric shock touch hazard. Installer must ensure that installation complies with local rules and general best safety practices.

For more information on diversion loads click here.

For higher Ohm ratings take a look at our stove element solutions.

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