Watts, Volts, I am lost!

[matt b]

Ok, So we just a bit of IKE. Half the city is without power. I am luck I have it. Tomorrow I am going to get a battery back up. I plan on getting a huge car battery and a car battery inverter. So say one power head takes up 8.5w. Does that mean it is going to use 8.5 watts a min? I plan on using a 300w heater and a koralia 4. That will be around 309w. What size car battery should I get? I want to be able to run this for a few days.

 

[geoj]

The a car batt wont do it, think how long it takes to run down with the headlights.

 

[wattsupdoc]

You need a deep cycle battery, a regular car battery wont work. Well it'll work, but you liable to ruin it in the process. Also, you would need to charge it periodically. You not going to be able to go a few days. 309 w hours is what you got there. /12v is 25.75 amp hours, that's what your going to draw from the battery. SOOOOO....IF you can get your hands on a good 100amp hour true deep cycle battery, you could go around 4m hours before it was depleted. Then you would need to recharge. Of course this assumes that the heater is running continuously, which it wont, so insulating the tank to prevent heat loss by wrapping it in a blanket etc. will greatly extend that time.