run to radioshack and buy an inverter.
get the battery out of your car.
connect the inverter and the battery.
take the filter pads out of the filter and just run it to keep the water stirred and also hook your heater to the same set up. It should run for about 3-5 days. you can always charge the battery back up in the car.
this set up worked fine for me.
Good luck.
...rick