Please do not turn on an inverter just to power a USB output, which charges most all smartphones to my knowledge. I know the little adapter fits nicely in an inverter and it makes it feel like like a stick and brick home, but here is what is happening.
The little wall adapter provided whith your smartphone, is taking 115volts AC and converting it to 5 volts DC. The inverter is taking ~12volts DC inverting it to 115 AC, then the phone provided plug in USB adapter is converting it back to 5 volts DC. At 85% efficiency at best.
The Inverter might even have a USB output, so you do not need to use your cell phone provided transformer. This is a meaningless bell and whistle. DO not let this feature sway you to purchase one inverter over another.
It makes more sense to have a DC to DC converter which takes 12.xx volts DC and converts it to 5 volts DC. There is much less wasted energy in this. Significantly less.
I hate common ciggy plugs for 60+ watt loads, but the link below will have devices which plug into the common 12v/ Ciggy receptacle, and draw much much less than this and will charge a cell phone or an Ipad or other tablets at the full 2.1 amp rate. Some of them can do 3.1 amps. Some can do even more.
These have such small parasitic draws when they are not actually charging anything that they are almost ignorable. I think I have 2 turned on right now. I know I have a third one that is powered and powering nothing, but it only draws 0.015 amps.
The same cannot be said for an inverter. It is likely using a minimum of 0.4 amps just turned on and powering nothing. My 800 watt MSW inverter uses 0.9 amps just turned on powering nothing. My 400 watt PSW wagan is about 0.4 amps.
Scenario: Say you fall asleep with the inverter on to charge a smartphone. It takes about an hour to fully charge the phone, then for 7 more hours, the inverter, turned on powering nothing, consumes 4 times the battery power that the phone actually needed to reach full charge.
Please do not use an inverter to just recharge your smartphone. Yes it works, but it is extremely wasteful when one is living off of a 12v battery. The goal when living off a 12v battery, it to keep it at as high a state of charge as possible at all times, so why consume more of it than needed?
http://www.amazon.com/s/ref=nb_sb_s...ive,245&rh=n:15684181,k:usb+car+adapter&ajr=0.
I can personally recommend this one, at least for android Phones, I bought one for my Sister who has an Iphone and she say it works perfect.
http://www.amazon.com/TopG-Smart-Ch...d=1403592272&sr=1-10&keywords=usb+car+adapter
Veteran Vandwellers don't let newbies use inverters to charge cell phones. Pass it around, steer them right, Please. I'm tired of repeating this to every person who signs up, and believes they need an inverter to recharge a cell phone, or a laptop for that matter.
For laptops, same thing, the laptop wants ~19 v DC. DC to DC converters exist to take 10.5 to 15.0 volts DC and convert it directly to 19.5vDC or whatever the laptop desires. Using an inverter works. It works fine, even an MSW inverter, but it will use at least 15% more, and likely a much higher percentage more battery power, to use an inverter to power the provided power brick/wall wart, than it will to use a DC to DC converter.
http://www.amazon.com/Spal-Magsafe-...1403592933&sr=1-6&keywords=laptop+car+adapter
http://www.amazon.com/Charger-Latit...ywords=dell+latitude+e5500+laptop+car+adapter
Just change the search to your specific laptop make and model, and it will likely be cheaper than the inverter.
An inverter is not the answer for everything, though it seems to be the Newbie Standard Answer for everything. If your not worried about using too much battery power or only using the inverter when driving somewhere, fine. But if you are worried about running the battery too low, but then use wasteful methods to recharge USB devices, or laptops, then you are basically shooting yourself in the foot. But then perhaps money is not an object for you either either. What is the first word which follows the www in the address bar?
About the MSW vs PSW, many of these wall warts or power bricks( power transformers) that come to recharge or to power certain devices, well they get warm. The might get warmer on MSW then PSW. That extra heat is your battery being wasted faster. That extra heat might, over time, cause the power supply to fail. There is a chance, albeit small, that a MSW inverter fries a power supply right off the bat. Definitely monitor the temperature of your power brick or wall wart when using a MSW inverter for the first few times, especially when plugging in a laptop with a dead battery. If it is hotter than you remember it ever feeling, or you smell hot plastic, then it does not like MSW. If so, Disconnect it or you might be purchasing another power supply, and then a PSW inverter, or better yet the car adapter.
No Need to monitor the transformer heat with PSW as the energy is as clean or perhaps even cleaner than what comes from the power grid.
Sure you can get a 30$ MSW inverter, perhaps cheaper, and you will have the meaningless comfort of using the manufacturer supplied power transformer. It will work. it Should work fine. It will work your battery over faster than DC to DC converter.
There are a few devices which absolutely require PSW. Most wall warts/ power bricks, these power transformers will work fine on MSW, but they might get hotter, and that heat is wasted battery power.
They might cause a 60 HZ buzzing in amplified speakers. They might cause radio noise, especially on AM radio. They might knock out some TV stations if you are using an Antenna.
The PSW inverter should be more friendly in these regards.
