Add the wattage of all the appliances you'll be wanting to operate, simultaneously, and that total is the correct wattage of the converter you'll need.

I try to keep everything 12v. My cooler and cell phone charger are 12v. I only use the converter to operate a 13" TV, and a PS2. I get by with a 400w converter plugged into one of the 12v receptacles. Easy.

Originally Posted by rdubill

so you don't have a cooler or microwave?

I'm sure those probably need much more power...

Do you keep them plugged in all night while sleeping? what is the impact on your battery then?

thanks

Compact microwave .7 cu. ft. is 1200 watt. So if you will not take in consideration loses in your inverter current of 1200/12=100 amps will be necessary from your battery to run that microwave. And if you add loses in inverter and so on, (no electrical guy here, but that sure over 20%) you’ll end up with min current of 120 amps. from your batteries. So let say you baking potato that would take 4 minutes (=.07 hours). You’ll use 120x.07=8.4 amp.hours from your batteries, which is not a big deal. However, I’d guess current of 120 amps would not help those batteries to survive. On another hand you won’t be paying for those batteries, so …. Also your wiring should be able to handle that current. Frige wont take that much power, but probably 1/10 of it or less. There are 12V friges installed in small motor homes, boats and so, that would be better than 110V AC through the inverter.

Originally Posted by 2xR

Add the wattage of all the appliances you'll be wanting to operate, simultaneously, and that total is the correct wattage of the converter you'll need.

I try to keep everything 12v. My cooler and cell phone charger are 12v. I only use the converter to operate a 13" TV, and a PS2. I get by with a 400w converter plugged into one of the 12v receptacles. Easy.

In case it's still not clear, I use a 12v cooler, not a 120v refrigerator.

Overnight usage has no effect on the batteries, because the only time my engine gets shut down is while fueling, if it breaks down, or when I park at the terminal to go home for a few days.

No microwave in my truck. I let the restaurants cook my meals.