Say you have a 500W pure sine-wave inverter and you want to power a 1500W sandwich toaster or a 3000W tea kettle during a power cut. These resistive devices are only that powerful for a rapid warm-up time - once at temp the toaster cycles on and off with a brief duty cycle, and the kettle only runs for a couple of minutes. The batteries powering the inverter have more than enough energy to make a sandwich or a cup of tea, but not enough power to run the devices at rated power (mostly because it's a 12V system: 3000W @ 12V = 250A. Not feasable!)
I'm looking for a solution for running these devices at 500W so the inverter would be able to run them in a pinch. So basically the toaster takes 3x longer to heat up (and thermostat duty-cycle becomes 3x longer to maintain temperature), and the kettle takes 6x longer to boil water.
I've thought of a thyristor dimmer, but I very much doubt this would play nice with the inverter because of the way it chops up the wave and feeds full power to the load in partial, 50Hz bursts.
A variac would work, but too bulky and expensive.
Buying dedicated low-power "camping" appliances would be a neat solution, but defeats the purposes of this question
I imagine a resistor in series would dissipate too much power to be feasable.
I've had great success using a 10uF 400V capacitor in series to limit the power to a 50W stand-fan (reducing it to 37W), however I don't know whether the idea would scale up to loads with thousands of watts.
I'm looking for a solution for running these devices at 500W so the inverter would be able to run them in a pinch. So basically the toaster takes 3x longer to heat up (and thermostat duty-cycle becomes 3x longer to maintain temperature), and the kettle takes 6x longer to boil water.
I've thought of a thyristor dimmer, but I very much doubt this would play nice with the inverter because of the way it chops up the wave and feeds full power to the load in partial, 50Hz bursts.
A variac would work, but too bulky and expensive.
Buying dedicated low-power "camping" appliances would be a neat solution, but defeats the purposes of this question
I imagine a resistor in series would dissipate too much power to be feasable.
I've had great success using a 10uF 400V capacitor in series to limit the power to a 50W stand-fan (reducing it to 37W), however I don't know whether the idea would scale up to loads with thousands of watts.