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For some time now, I 've used a twelve dollar 150 watt inverter to keep my cellphone, bluetooth, HP camera, 2 laptops, Garmin GPS running and my back-up batteries fully charged.  It is small, cheap, will not run down your car battery, and can be plugged directly into your standard 12vdc lighter.   I think the published limit for lighter outlets in most cars is about 150 watts, anyway.  After extended, hard use I've never even blown a fuse, though I carry spares.

If you go larger than that, you should power your inverter directly from the car's battery with appropriately-sized fuse protection and both under-hood and under-dash disconnecting means.    It is fairly easy to find an existing hole through which to route the wire(s) from the engine compartment into the dashboard area.   Be sure to protect and secure any wiring you install under the hood.   All this should take under an hour and cost less than ten bucks at an auto-parts store.

For most users, 400 wattts and up is overkill.  It 's expensive, it drains your battery, and you just don't need it.  If you need to run  printers, microwaves, coolers, anti-aircraft lasers, or a bunch of other peripherals, its another matter.  But for most of us, this is a good place to conserve energy.

Rich R

I am "inverter challenged" and need a little help. I have always used an old 220 watt inverter to run my laptop and printer from the vehicle to close files in the field. However, that was with a f/s pickup. Recently, I downsized to a 4 cyl. Toyota RAV4 and am wondering if this will run both the laptop and printer w/o blowing fuses. I made the mistake of connecting a laser jet printer and the fuses were tough to get to after they immediately blew. Also, can you run a 3 in 1 type (printer/scanner/copier) with an inverter. I remember hooking up an old Canon personal copier once and the fuses in the truck blew right away. Thanks for any advise.

DHOLMAN:

Here are the two answers to your two questions:  Yes, you can use your inverter;  No, you can't run your 3-in-one off the inverter.  Leave that power-hog in the hotel, and invest in a more eco-friendly printer for your Rav4.  Tom Toll (above) chose the HP 470, a small, feature-laden, power miserly,  wireless $250 inkjet.  I bought the Canon Pixma 2600 inkjet (large, power miserly, plug-in, USB hookup).  I paid $30 (yes, $30, at Wal-Mart). 

Explanation:

Question one:   Your Rav4 is more than adequate to run your inverter.  But since your inverter is over 200 watts, you should connect it directly to the battery in the manner described in my earlier post.  You could get away with using 10-2 Romex as  rickhans (above) did, but if a fire started under your hood, your auto coverage might also go up in smoke.  I recommend using #10 automotive wire with slip-on plastic jacketing.  This way it will appear factory-installed.  Use an in-line fuse (30 amp for #10 wire, or 20 amp for #12) .

Question two:  Your 3-in-1 printer draws too many amps.  My HP 3055 runs 540 watts. The nameplate says 4.5 amps @ 120 volts.  Ohm's Law says P=IE (watts = amps times volts, or 540 watts = 4.5 amps times 120 volts.  If you reduce the volts to 12 (you car battery output), the number of amps drawn will increase to 45.  This means a larger, more expensive inverter and much heavier wire and fuse size.  My $30 Canon printer draws uses only 84 watts (.7 amps at 120 volts, or 7 amps at 12 volts.).  Ditto for the HP 470.   Either will be well with in the capacity of your 220 watt inverter.

I hope this helps.

RRobinson   

While I understand Ohm's Law I also have been running an inverter for years, on a day in and day out basis, my inverter runs 24 hours a day 365 days a year and I offer this piece of advice, absolute reliability is the key to using this system to make money.Go with overkill, use a 400 watt inverter wired with a fuse directly to the battery.

Plug in a short extension cord and use it to run your camera battery charger, a cell phone charger,a video camera battery charger, a flashlight battery charger and anything else that needs 110V.

Additionally I run a custom made alternator with triple diodes mounted on the outside, and two expensive batteries. My batteries have a trickle charger installed and there is an extension cord under the hood of my truck.

Again when your money depends on it go with overkill, heavy duty and redundant.

I know that I will not have problems should I go work Bill in Cape Cod.

ChuckDeaton runs a lot more stuff than I do, and runs longer and harder than I do.  For him, 400 w (or 1,000 w) is definitely not overkill.  My uses are minimal, and I'm too much of a tightwad to buy much more capacity than I need.  However, his point on reliability was good.  A 400 w inverter should of course last longer in my rig that my 150 w, even though I seldom consume more than 100 w. 

I don't know much about AC theory, but with identical 100 w loads on a 150 w and  a 400 w inverter, I'll bet that the 400 w inverter would draw very little more current than the 150.  Raise the loads to 150 w, the smaller inverter might get smoking hot, while the larger unit would hardly notice the difference.   Further, as ChuckDeaton pointed out, a failure in the field could be tragic.  I think I'll keep my present system, but buy a backup (larger) inverter in case my 150 craps out.