Power Inverter Sizing Help!!

Guess i'm wanting to pick up a power inverter to put in the ole ridgy. My plan is to have a receptacle in the trunk and another in the cab(probably in the center console). My concern is I'm not sure how large of one i'll need! I want something that if i take my small air compressor 2 HP 4 gallon contractor compressor out to use i can hook it up and have it run. The compressor i got from harbor freight and am not sure the amp draw. Basically i don't want overkill but at the same time if i go tailgating and want to put a tv or some lights on this inverter i don't want to have to worry bout it. How do i know much i need? Thanks guys

Here is my limited knowledge of electrical generation based on what I learned at Navy Nuke school.

Amps X volts = Power (watts)

Our alternators are rated at 130 amps at 12 volts.

130amps X 12volts = 1,560 watts.

Any inverter over 1,500 watts is gonna overload your alternator.

Not sure what your lighting plan is, but I run 5 fluorescents @ 14 watts that are the equal to 60 watt incandescents and have them in the clip on aluminum trouble/spot light fixtures. I run these and my 13" TV/DVD and satellite box all off a 400 watt inverter that is wired directly to a pair of deep cycle marine batteries.
I also use a Black & Decker Powermate that has the jump start, air compressor and a 400 watt inverter built in and it will run my lights and TV for about 2 1/5 - 3 hours between charges.

Good advise on the alternator issue. My biggest concern is pulling to many amps and poping the circuit breaker all the time. Like i said the biggest thing i would probably run would be my portable air compressor it's got a 2 HP motor oiled with 4 gallon res.

More math! 1 HP = 746 watts

2 HP = 1,492 watts

At 12 volts, that will draw 125 amps. Throw in a few amps lost to resistance, and thats pushing the alternator rating and you would be popping fuses in any existing circuit. You would have to hardwire it to the alternator on it's own circuit. I think 2 HP would be tough.

Somebody with a bit more knowledge, jump in here if I'm fundamentally mistaken.

1HP = 746 watts at 100% efficiency, which motors are not. You're looking at 3KW at 50% efficiency for your compressor. Induction motors also have a very high starting current spike which can be up to 10x their normal running draw. This is going to be your problem. It will pop your breaker.

You need a generator, not an inverter.

hmm Seems as though you guys are right it would be pushing it. I would imagine though that a 100watt would work for anything else though right?

This should help.

EERE Consumer's Guide: Estimating Appliance and Home Electronic Energy Use (http://www.eere.energy.gov/consumer/your_home/appliances/index.cfm/mytopic=10040)

Power outlets in dash and console should be able to handle 120watts I believe. Here is a plug-in solution with my 150watt inverter. Mounting on the front portion of the console near the floor keeps it out of sight but easily accessable for cell, PDA, notebook, or GPS etc charging. Hide wire along the gap between passenger seat as it runs to the power outlet in the back seat area. Cord is taped because I often load the back seat with boxes which have crushed it in the past. This leaves both front outlets free and cord less obtrusive which works for me.

I don't push any more than that so I'm maxing at about 100w at worst. Any more power needed and it's wise to go around the power outlets.